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Applications of Chitosan in Molecularly and Ion Imprinted Polymers
Abstract
Chitosan is a natural polysaccharide derivative of chitin component that has been used in a wide range of fields because of their outstanding advantages, including non-toxicity, biodegradability, biocompatibility, anti-allergic, anticoagulant, antifungal and antimicrobial. Due to its excellent properties, it attracted significant attention in numerous applications such as medicine, food, and analysis fields. Recently, this polymer has been broadly utilized for the preparation of molecularly imprinted polymers (MIPs) and MIP composites. MIP is a synthetic receptor obtained by the polymerization of functional monomers in the presence of a template. The extraction of the template leaves behind specific cavities. In fact, according to our bibliographic studies about this topic, we found that chitosan is generally used in two different ways: (1) as imprinting polymer with a selected crosslinking agent to create specific cavities for the template, and (2) as additive material for MIP composite preparation. That is exactly the main goal of this review, which will be focused on discussing the roles of chitosan for MIP and MIP composite elaborations, after presenting some generalities about chitosan and MIP. A brief overview of the recent applications of MIPs and MIP composite based on chitosan is presented, but the focus is primarily put on separation and sensing applications. Among that, those designed to separate/detect heavy metals, drugs, biomolecules, and pesticides are highlighted.
... In addition, since 2013, the preparation of composite IIPs for the selective separation of HMIs has also received growing attention from the scientific community ( Figure 1). IIPs exhibit similar features as MIPs, the main difference being related to the specific recognition sites that are inorganic ions after the imprinting process in the case of former IIPs exhibit similar features as MIPs, the main difference being related to the specific recognition sites that are inorganic ions after the imprinting process in the case of former ones [30][31][32][33][34][35][36][37][38]. The strategies applied to prepare MIPs have been also adapted to the synthesis of IIPs and they will be briefly described in the next section of this review. ...
... However, all of the approaches follow a similar outline, as can be seen in Figure 2, where the imprinting process using functional monomers as a ligand is depicted. ones [30][31][32][33][34][35][36][37][38]. The strategies applied to prepare MIPs have been also adapted to the synthesis of IIPs and they will be briefly described in the next section of this review. ...
... As Figure 2 shows, the IIP synthesis is based on three steps: (i) in the first step, a complex between metal ion (template) and ligand functional groups of the host (monomers) is generated by non-covalent interactions (chelation, electrostatic interactions, and hydrophobic interactions); (ii) in the second step, the polymerization of this complex and the stabilization of the binding cavities are achieved using a bi-functional monomer (cross-linker); (iii) in the third step, the template ion is leached from the copolymer host using adequate compounds, and thus specific cavities available for selective rebinding are created [30][31][32][33][34][35][36][37][38]. To prove the existence of pre-organized recognition sites, in the fourth step (Figure 2), the IIPs are exposed to the template ion, and the imprinted cavities are thus selectively filled by the target metal ion [38]. ...
The introduction of selective recognition sites toward certain heavy metal ions (HMIs) is a great challenge, which has a major role when the separation of species with similar physicochemical features is considered. In this context, ion-imprinted polymers (IIPs) developed based on the principle of molecular imprinting methodology, have emerged as an innovative solution. Recent advances in IIPs have shown that they exhibit higher selectivity coefficients than non-imprinted ones, which could support a large range of environmental applications starting from extraction and monitoring of HMIs to their detection and quantification. This review will emphasize the application of IIPs for selective removal of transition metal ions (including HMIs, precious metal ions, radionuclides, and rare earth metal ions) from aqueous solution by critically analyzing the most relevant literature studies from the last decade. In the first part of this review, the chemical components of IIPs, the main ion-imprinting technologies as well as the characterization methods used to evaluate the binding properties are briefly presented. In the second part, synthesis parameters, adsorption performance, and a descriptive analysis of solid phase extraction of heavy metal ions by various IIPs are provided.
... It is present in the cell walls of several fungal strains, especially zygomycota, and is becoming attractive as a new functional material in various analytical, industrial, environmental and biomedical fields. The largest producers of chitosan are in Japan, India and Norway [107,108]. Chitosan is used for the preparation of MMIPs is depicted in Figure 3. MMIP made by combining the advantages of chitosan is expected to produce new and more profitable materials. Chitosanbased composites have emerged as promising materials with excellent thermal, mechanical, electrical and optical properties, which play an important role in the elaboration of MMIP composites [108]. ...
... Chitosan is used for the preparation of MMIPs is depicted in Figure 3. MMIP made by combining the advantages of chitosan is expected to produce new and more profitable materials. Chitosanbased composites have emerged as promising materials with excellent thermal, mechanical, electrical and optical properties, which play an important role in the elaboration of MMIP composites [108]. The problem faced in the formation of Fe 3 O 4 NPs is that nanoscale particles with a large surface-to-volume ratio will cause aggregation during particle formation, through van der Waals attraction between particles. ...
... It is present in the cell walls of several fungal strains, especially zygomycota, and is becoming attractive as a new functional material in various analytical, industrial, environmental and biomedical fields. The largest producers of chitosan are in Japan, India and Norway [107,108]. Chitosan is used for the preparation of MMIPs is depicted in Figure 3. MMIP made by combining the advantages of chitosan is expected to produce new and more profitable materials. Chitosan-based composites have emerged as promising materials with excellent thermal, mechanical, electrical and optical properties, which play an important role in the elaboration of MMIP composites [108]. ...
During the last few years, separation techniques using molecular imprinting polymers (MIPs) have been developed, making certain improvements using magnetic properties. Compared to MIP, Magnetic molecularly imprinted polymers (MMIPs) have high selectivity in sample pre-treatment and allow for fast and easy isolation of the target analyte. Its magnetic properties and good extraction performance depend on the MMIP synthesis step, which consists of 4 steps, namely magnetite manufacture, magnetic coating using modified components, polymerization and template desorption. This review discusses the factors that will affect the performance of MMIP as a selective sorbent at each stage. MMIP, using Fe3O4 as a magnetite core, showed strong superparamagnetism; it was prepared using the co-precipitation method using FeCl3·6H2O and FeCl2·H2O to obtain high magnetic properties, using NH4OH solution added for higher crystallinity. In magnetite synthesis, the use of a higher temperature and reaction time will result in a larger nanoparticle size and high magnetization saturation, while a higher pH value will result in a smaller particle size. In the modification step, the use of high amounts of oleic acid results in smaller nanoparticles; furthermore, determining the correct molar ratio between FeCl3 and the shielding agent will also result in smaller particles. The next factor is that the proper ratio of functional monomer, cross-linker and solvent will improve printing efficiency. Thus, it will produce MMIP with high selectivity in sample pre-treatment.
... Tianwei at al. demonstrated that a Ni(II)-imprinted chitosan resin, obtained by crosslinking with epichlorohydrin and ethylene glycol diglycidyl ether, had a good chemical and physical stability and could be used many times without losing adsorption capacity, considerably enhancing the adsorption capacity and the selectivity toward metal ions [39]. From then to now, tremendous progress has been made as it has been summarized in some interesting reviews with this focus [40][41][42]. Xu et al. [40] wrote a review on the use of chitosan in MIPs in which described the commonly used crosslinkers agents, highlighting the crosslinking mechanisms. In 2020, two other reviews appeared dealing with CS-based MIPs with the aims to provide an overview of the value to use chitosan as a functional monomer with a focus on its applications in electrochemical sensors [41], while Karrat et al. presented a brief overview of the recent applications of MIPs and IIPs composites based on chitosan with the focus on separation and sensing applications [42]. ...
... Xu et al. [40] wrote a review on the use of chitosan in MIPs in which described the commonly used crosslinkers agents, highlighting the crosslinking mechanisms. In 2020, two other reviews appeared dealing with CS-based MIPs with the aims to provide an overview of the value to use chitosan as a functional monomer with a focus on its applications in electrochemical sensors [41], while Karrat et al. presented a brief overview of the recent applications of MIPs and IIPs composites based on chitosan with the focus on separation and sensing applications [42]. ...
... Moreover, recently an increasing number of examples of MIPs or IIPs combined systems, in which chitosan has been combined with other materials, mainly nanomaterials, has been observed. In these contexts, we can cite the use of magnetic nanoparticles, graphene, multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (AuNPs) capable of adding other optimal properties such as magnetic, electrical or high surface area [42]. ...
Molecular Imprinting Polymer (MIP) technology is a technique to design artificial receptors with a predetermined selectivity and specificity for a given analyte, which can be used as ideal materials in various application fields. In the last decades, MIP technology has gained much attention from the scientific world as summarized in several reviews with this topic. Furthermore, green synthesis in chemistry is nowadays one of the essential aspects to be taken into consideration in the development of novel products. In accordance with this feature, the MIP community more recently devoted considerable research and development efforts on eco-friendly processes. Among other materials, biomass waste, which is a big environmental problem because most of it is discarded, can represent a potential sustainable alternative source in green synthesis, which can be addressed to the production of high-value carbon-based materials with different applications. This review aims to focus and explore in detail the recent progress in the use of biomass waste for imprinted polymers preparation. Specifically, different types of biomass waste in MIP preparation will be exploited: chitosan, cellulose, activated carbon, carbon dots, cyclodextrins, and waste extracts, describing the approaches used in the synthesis of MIPs combined with biomass waste derivatives.
... In the overall scenario of sample treatment, magnetic solid-phase extraction (SPE) has been widely applied to sample preparation in the environment, biological, and food samples. SPE is a method in which the compounds in a liquid solution are selectively adsorbed on a solid phase according to their physicochemical properties [17][18][19]. Even though SPE offers several advantages, it faces some problems such as cartridge blocking, time-consuming, and difficulty in performing simultaneous extractions. ...
... Recently, magnetic nanoparticles (MNPs) and functionalized MNPs have been used in a wide range of fields because of their outstanding advantages including large surface area, simple separation using magnetic fields, and easiness in the functionalization [17,29,30]. The coating of MNPs with the amphiphilic polymer does not have only a high affinity to amphiphilic compounds but also high magnetic properties facilitating the separation process. ...
The development of enhanced and cost-effective materials for the adsorption and determination of pesticides in water is urgently required. Dicofol is an acaricide belonging to persistent organic pollutants that can lead to several diseases including cancer, passiveness, ataxia, vomiting, and affects sex hormones. In this study, we synthesized a magnetic amphiphilic poly(methacrylic acid-co-styrene) material that can be used either for the removal or analytical determination of dicofol in an aqueous medium. This sorbent was successfully prepared through free-radical polymerization of methacrylic acid (MAA) and styrene in the presence of magnetic nanoparticles using a fast synthesis technique based on ultrasonic waves. The magnetic nanoparticles and the amphiphilic sorbent were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and thermal gravimetric analysis, which confirmed the modification of the magnetic nanoparticles with the co-polymer. A theoretical study was applied to investigate the interactions sites in dicofol and the poly(MAA-co-styrene), suggesting the high affinity of the synthesized material towards dicofol. The developed sorbent exhibited a fast (5 min), and high maximum adsorption capacity (43.47 mg g−1) combined with high selectivity towards dicofol, following the kinetic pseudo-second-order model and the isotherm Freundlich model. This material was successfully used as a selective adsorbent in solid-phase extraction for the determination of dicofol. Under optimized conditions, namely the amount of the sorbent, the elution solvent, and the elution time, a pre-concentration factor of 25 was obtained and exploited to detect dicofol in the water sample.Graphical Abstract
... Despite the promising and evidenced utilization of Chitosan in paper-sizing [1], the food industry [2], pharmaceuticals, Veterinary medicine [3,4] medicine [5,6], separation processes [7][8][9], and energy systems such as fuel cells [10,11], and at different application sizes such as the Nano and micro scales [12][13][14], as well as in the area of molecular imprinting [15][16][17][18], its extensive use in a diversified industrial economy has been limited due to its hydrophilic nature and narrow application temperature tolerance. ...
... The presence of characteristic strong and broad band peak ranges from 3700-3200 cm −1 , which are the extension vibration of the N-H functionality and the O-H vibrational stretching of ungrafted or uncross-linked Chitosan molecule, presents support for the cross-linked grafting of Chitosan and Methacrylic acid in the presence of 1,4-Bis (Acryloyl) piperazine (BAP). It is further observed that a shift towards the asymmetric and symmetric -CH2 functionality is evidenced in Figure 8, with increased prominence of peaks within the range of 2920s and 2869s [16,17]. From the FTIR spectra of the template eluted MIP samples (Figure 9), the prominent peaks are as shown in ESD III and the representative functional groups are likewise identified as previously shown in Figure 8. ...
This study reports the feasible use of chitosan as a thin film biosensor on the very sensitive
quartz crystal micro balance system for detection of blends of multiple templates within a single
matrix. The development of chitosan-based thin film materials with selectivity for nicotine derivatives is described. The molecular imprinting of a combination of nicotine derivatives in N-diacryloyl
pipiradine-chitosan-methacrylic acid copolymer films on quartz crystal resonators was used to generate thin films with selectivity for nicotine and a range of nicotine analogues, particularly 3-phenylpyridine. The polymers were characterized by spectroscopic and microscopic evaluations; surface area, pore size, pore volume using Breuner-Emmet-Teller method. Temperature characteristics
were also studied. The swelling and structure consistency of the Chitosan was achieved by grafting
with methylmethacrylic acid and cross-linking with N-diacrylol pipiradine. A blend of 0.002 g (0.04
mmol) of Chitosan, 8.5 μL Methylmethacrylic Acid and 1.0 mg N-diacrylol pipradine (BAP) presented the best blend formulation. Detections were made within a time interval of 99 sec, and blend
templates were detected at a concentration of 0.5 mM from the Quartz crystal microbalance resonator analysis. The successful crosslinking of the biopolymers ensured successful control of the swelling and agglomeration of the chitosan, giving it the utility potential for use as thin film sensor. This
successful crosslinking also created successful dual multiple templating on the chitosan matrix,
even for aerosolized templates. The products can be used in environments with temperature ranges
between 60 °C and 250 °C.
... Despite the promising and evidenced utilization of Chitosan in paper-sizing [1], the food industry [2], pharmaceuticals, Veterinary medicine [3,4] medicine [5,6], separation processes [7][8][9], and energy systems such as fuel cells [10,11], and at different application sizes such as the Nano and micro scales [12][13][14], as well as in the area of molecular imprinting [15][16][17][18], its extensive use in a diversified industrial economy has been limited due to its hydrophilic nature and narrow application temperature tolerance. ...
... The presence of characteristic strong and broad band peak ranges from 3700-3200 cm −1 , which are the extension vibration of the N-H functionality and the O-H vibrational stretching of ungrafted or uncross-linked Chitosan molecule, presents support for the cross-linked grafting of Chitosan and Methacrylic acid in the presence of 1,4-Bis (Acryloyl) piperazine (BAP). It is further observed that a shift towards the asymmetric and symmetric -CH2 functionality is evidenced in Figure 8, with increased prominence of peaks within the range of 2920s and 2869s [16,17]. From the FTIR spectra of the template eluted MIP samples (Figure 9), the prominent peaks are as shown in ESD III and the representative functional groups are likewise identified as previously shown in Figure 8. ...
This study reports the feasible use of chitosan as a thin film biosensor on the very sensitive quartz crystal micro balance system for detection of blends of multiple templates within a single matrix. The development of chitosan-based thin film materials with selectivity for nicotine derivatives is described. The molecular imprinting of a combination of nicotine derivatives in N-diacryloyl pipiradine-chitosan-methacrylic acid copolymer films on quartz crystal resonators was used to generate thin films with selectivity for nicotine and a range of nicotine analogues, particularly 3-phe-nylpyridine. The polymers were characterized by spectroscopic and microscopic evaluations; surface area, pore size, pore volume using Breuner-Emmet-Teller method. Temperature characteristics were also studied. The swelling and structure consistency of the Chitosan was achieved by grafting with methylmethacrylic acid and cross-linking with N-diacrylol pipiradine. A blend of 0.002 g (0.04 mmol) of Chitosan, 8.5 μL Methylmethacrylic Acid and 1.0 mg N-diacrylol pipradine (BAP) presented the best blend formulation. Detections were made within a time interval of 99 sec, and blend templates were detected at a concentration of 0.5 mM from the Quartz crystal microbalance resona-tor analysis. The successful crosslinking of the biopolymers ensured successful control of the swelling and agglomeration of the chitosan, giving it the utility potential for use as thin film sensor. This successful crosslinking also created successful dual multiple templating on the chitosan matrix, even for aerosolized templates. The products can be used in environments with temperature ranges between 60 °C and 250 °C .
... Furthermore, the presence of hydroxyl and amine groups in chitosan allows interaction with a great variety of template molecules by hydrogen-bonding even in aqueous media, which represents a remarkable advantage over conventional (meth)acrylic MIPs, and facilitates its modification by reaction with different cross-linking agents, such as aldehydes (glutaraldehyde), epoxides (epichlorohydrin), and acids (sulfuric acid), among others. Figure 4 shows a schematic illustration for the preparation of chitosan-based MIPs [40], which can F I G U R E 3 Different MIPs for the recognition of (A) different tanshinones (cryptotanshinone (A), tanshinone I (B), tashinone IIA (C) and template, 9,10-phenanthrenequinonea (D)), prepared by modifying porous polymers with ionic liquids (B). Reproduced from reference [38] with permission from Springer F I G U R E 4 Schematic illustration for the preparation of chitosan-based molecularly imprinted polymers (MIPs). ...
... Reproduced from reference [38] with permission from Springer F I G U R E 4 Schematic illustration for the preparation of chitosan-based molecularly imprinted polymers (MIPs). Reproduced from reference [40] with permission from Springer be easily adapted to microextraction techniques such as pipette-tip microextraction [41], dispersive magnetic SPE [42], or ultrasound-assisted dispersive SPE [43], among others. However, in spite of the inherent mentioned advantages, some issues related to the polymerization process and cross-linking mechanism of chitosan remain unclear limiting its general use. ...
The use of molecularly imprinted polymers in sample preparation as selective sorbent materials has received a great attention during last years leading to analytical methods with an unprecedented selectivity. However, with the progressive implementation of Green Analytical Chemistry principles, it is necessary to critically review the greenness of synthesis and further use of molecularly imprinted polymers in sample preparation. Accordingly, in the present review, the different steps and strategies for the preparation of molecularly imprinted polymers, the used reagents, as well as their incorporation to microextraction techniques are reviewed form a green perspective and recent alternatives to make the use of molecularly imprinted polymers more sustainable are provided. This article is protected by copyright. All rights reserved
... 2020 [21] Applications of chitosan in molecularly and ion imprinted polymers A brief overview of recent applications of chitosan-based MIPs and MIP composites. 2020 [22] MIPs-towards electrochemical sensors and electronic tongues ...
... There is also a growing interest in imprinted chitosan-based electrochemical sensors. The reader is referred to [22,24,25] for details. ...
This review critically summarizes the knowledge of imprinted polymer-based electrochemical sensors for the detection of pesticides, metal ions and waterborne pathogenic bacteria, focusing on the last five years. MIP-based electrochemical sensors exhibit low limits of detection (LOD), high selectivity, high sensitivity and low cost. We put the emphasis on the design of imprinted polymers and their composites and coatings by radical polymerization, oxidative polymerization of conjugated monomers or sol-gel chemistry. Whilst most imprinted polymers are used in conjunction with differential pulse or square wave voltammetry for sensing organics and metal ions, electrochemical impedance spectroscopy (EIS) appears as the chief technique for detecting bacteria or their corresponding proteins. Interestingly, bacteria could also be probed via their quorum sensing signaling molecules or flagella proteins. If much has been developed in the past decade with glassy carbon or gold electrodes, it is clear that carbon paste electrodes of imprinted polymers are more and more investigated due to their versatility. Shortlisted case studies were critically reviewed and discussed; clearly, a plethora of tricky strategies of designing selective electrochemical sensors are offered to “Imprinters”. We anticipate that this review will be of interest to experts and newcomers in the field who are paying time and effort combining electrochemical sensors with MIP technology.
... 2020 [13] Applications of chitosan in molecularly and ion imprinted polymers A brief overview of recent applications of chitosan-based MIPs and MIP composites. 2020 [14] We have surveyed the recent progress in the design and applications of MIP-based electrochemical sensors of pesticides, metal ions and pathogenic bacteria. We emphasize the last five years: we cited 78 papers published in 2017-2021, ie 63% of total citations. ...
... Each case study section, devoted to a given pollutant, will describe either imprinted vinylic, conjugated or sol-gel polymeric materials prepared in thin films or as finely divided nanocomposite powders. Besides these polymers, there is growing interest in employing imprinted chitosan-based adsorbents in electrochemical sensors; the reader is referred to recent reviews and original articles [14][15][16]. ...
This mini-review critically summarizes the knowledge of imprinted polymer-based electrochemical sensors, for the detection of pesticides, metal ions and waterborne pathogenic bacteria, focusing on the period the last 5 years (citation of 78 papers published in 2017-2021, ie 63% of total citations). MIP-based electrochemical sensors exhibit low limit of detection, high selectivity, high sensitivity and low cost. Herein, we focused on the timely topics of water pollution by organics, inorganics and microorganisms represented by pesticides, metal ions and bacteria, respectively. We put the emphasis on the design of imprinted polymers and their composites and coatings by radical polymerization, oxidative polymerization of conjugated monomers or sol-gel chemistry. Whilst most imprinted polymers are used in conjunction with differential pulse or square wave voltammetry for sensing organics and metal ions, electrochemical impedance spectroscopy (EIS) appears as the chief technique for detecting bacteria. This successful combination of EIS and imprinting technology should be harnessed in the coming years in the case of bacteria. Interestingly, bacteria are not always probed by bacteria-imprinted polymers; we report here their detection by monitoring specific (macro)molecules that reflect bacterial activity, for example quorum sensing signaling molecules or flagella proteins. If much has been developed in the past decade with glassy carbon or gold electrodes, it is clear that carbon paste electrodes of imprinted polymers are more and more investigated due to their versatility. Shortlisted case studies were critically reviewed and discussed; clearly a plethora of tricky strategies of designing selective electrochemical sensors are offered to "Imprinters". We anticipate this review will be of interest to experts and new comers in the field who are paying time and effort combining electrochemical sensors with MIP technology.
... In the above context, over the past few decades, MIPs and MIPs-based materials have drawn more attention as attractive alternatives to trace analysis in complex matrices. MIPs have been used for wastewater pretreatment, trace ion concentration analysis, and heavy metal ion removal [158]. Table 3 summarizes recent reports on the selective removal of heavy metal ions from aqueous solution using MIPs and MIPs-based nanocomposites. ...
... If the electrode has a non-flat geometry, achieving a uniform layer of MIP through drop casting may be more difficult. PEG and chitosan are often used as immobilization matrices, but they could potentially reduce accessibility to the MIP interaction sites or introduce interferences [60]. ...
This review aims to elucidate recent developments in electrochemical sensors that use functionalized carbon electrodes with molecularly imprinted polymers (MIPs) for the selective detection of organic compounds in diverse fields including pharmacy, food safety, environmental monitoring of pollutants, and biomedical analysis. The main targets include explosive compounds, dyes, antioxidants, disease biomarkers, pharmaceuticals, antibiotics, allergens, pesticides, and viruses. Following a brief overview of the molecular imprinting principle, the most significant applications are explored. The selection of the functional monomer is subsequently discussed. Notably, various types of carbon electrodes are presented, with a particular emphasis on screen-printed carbon electrodes. The most commonly employed techniques for MIP deposition such as electropolymerization, drop casting, and chemical grafting are introduced and discussed. Electrochemical transduction techniques like cyclic voltammetry, differential pulse voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy are presented. Lastly, the review concludes by examining potential future directions and primary limitations concerning carbon electrodes modified with MIPs.
... Several studies used chitosan for MIP preparation [32][33][34]. Chitosan is a natural biopolymer that has non-toxic properties and is available sustainably. Chitosan has two active groups in its structure, namely an amine (-NH 2 ) group and a hydroxyl (-OH) group [35]. ...
Molecularly Imprinted Polymers (MIPs) have specific recognition capabilities and have been widely used for electrochemical sensors with high selectivity. In this study, an electrochemical sensor was developed for the determination of p-aminophenol (p-AP) by modifying the screen-printed carbon electrode (SPCE) with chitosan-based MIP. The MIP was made from p-AP as a template, chitosan (CH) as a base polymer, and glutaraldehyde and sodium tripolyphosphate as the crosslinkers. MIP characterization was conducted based on membrane surface morphology, FT-IR spectrum, and electrochemical properties of the modified SPCE. The results showed that the MIP was able to selectively accumulate analytes on the electrode surface, in which MIP with glutaraldehyde as a crosslinker was able to increase the signal. Under optimum conditions, the anodic peak current from the sensor increased linearly in the range of 0.5–35 µM p-AP concentration, with sensitivity of (3.6 ± 0.1) µA/µM, detection limit (S/N = 3) of (2.1 ± 0.1) µM, and quantification limit of (7.5 ± 0.1) µM. In addition, the developed sensor exhibited high selectivity with an accuracy of (94.11 ± 0.01)%.
... The molecular imprinting technique allows the preparation of polymers capable for the selective recognition of a specific molecule, commonly called "target molecule" [1]. The synthesis of molecularly imprinted polymer (MIP) is generally carried out in three steps: (i) the self-assembly of the functional monomers with the target molecule; (ii) the copolymerization of the functional monomers with a cross-linking agent to obtain a cross-linked polymer; and (iii) the extraction of the target from the polymer using an adequate solvent [2,3]. After the extraction of the target, the polymer matrix contains cavities with a predefined conformation for the selective recognition of the target [4,5]. ...
The extraction of templates from MIPs is not an easy task as well known, because of the high affinity between monomers and templates. Herein, a new strategy for the immediate removal of the template was developed. Two polymers were prepared, one for hexavalent chromium (Cr(VI)) and the other for rutin molecule, to overcome the extraction problem for ions and molecularly imprinted polymers. A diphenylcarbazide solution was used for removing Cr(VI), allowing an immediate extraction of this ion from the polymer. For rutin molecule, the aluminum solution allowed fast removal. Since these removal strategies imply extracting with coloration development, these elution solutions could be used simultaneously for the extraction and detection of the analyte. Indeed, an analytical reading kit has been 3D-printed for the Cr(VI) smartphone detection. In this tool, a column containing the ionic imprinted polymer (IIP) was used as sorbent and diphenylcarbazide solution for eluting and detecting Cr(VI). The developed sensor exhibited a detection limit of 0.006 µg mL⁻¹. The proposed procedure was applied successfully for Cr(VI) determination in tap and river waters showing satisfactory recoveries. These extraction methods pave the way for the application of other ligands for the gentle, fast and on-site removal of different templates.
... Due to these reaction possibilities, CS is commonly used as a supporting matrix in MIP synthesis. Furthermore, because of its high adsorption capacity and biocompatibility, CS is frequently utilized for the separation and detection of compounds in biological, environmental, and food samples (Karrat et al., 2020). In this presented work CS have dual performance as a supporting polymeric matrix and as a reducing agent. ...
... Chitosan is a biopolymer that is extracted from seafood waste, mostly from the carapace of shrimps [1,2]. Indeed, the valorization of this waste by the extraction of chitin and its deacetylation in a basic medium has led to the production of chitosan [3]. ...
In this work, chitosan beads were used as a cost-effective platform for the covalent immobilization of unmodified single-stranded DNA, using glutaraldehyde as a cross-linking agent. The immobilized DNA capture probe was hybridized in the presence of miRNA-222 as a complementary sequence. The target was evaluated based on the electrochemical response of the released guanine, using hydrochloride acid as a hydrolysis agent. Differential pulse voltammetry technique and screen-printed electrodes modified with COOH-functionalized carbon black were used to monitor the released guanine response before and after hybridization. The functionalized carbon black provided an important signal amplification of guanine compared to the other studied nanomaterials. Under optimal conditions (6 M HCl at 65 °C for 90 min), an electrochemical-based label-free genosensor assay exhibited a linear range between 1 nM and 1 µM of miRNA-222, with a detection limit of 0.2 nM of miRNA-222. The developed sensor was successfully used to quantify miRNA-222 in a human serum sample.
... Since the amine and alcohol groups can interact with different types of cross-linking agents and a special cavity is produced for many types of analyses, chitosan is a popular candidate for preparing molecularly imprinted polymers. Chitosan might be used as molecular imprinted chitosan (MICS) 8,41 in the development of strong electrochemical sensors. Food, cosmetics, pharmaceuticals, agricultural products, biosensors and gas sensors are among the most important applications of novel nanomaterials. ...
Iron oxide nanoparticles (NPs) have recently attracted wider attention because of their unique properties, such as superparamagnetism, larger surface area, surface-to-volume ratio, and simple manufacturing process. Several chemical, physical, and biological techniques have been employed to synthesize NPs with admissible surface chemistry. This paper summarises the approaches for producing iron oxide NPs, shape, and size management, and inviting properties in bioengineering, pharmaceutical, and modern applications. Iron oxides have significant potential in biology, climate change, and horticulture, among other fields. Surface coatings with organic or inorganic particles are one of a kind. The surface coatings of the IONPs are critical to their performance because they prevent nanoparticle aggregation, reduce the risk of immunogenicity, and limit nonspecific cellular uptake. Chitosan is a biodegradable polymer that is applied to iron oxide nanoparticles to coat them. Chitosan subordinates like O-HTCC (an ammonium-quaternary CS subsidiary) have a long-lasting positive charge that allows them to work in different pH ranges allowing their interactions with cell layers at physiological pH. By reacting epoxy propyl trimethyl ammonium chloride (ETA) with chitosan (CS), the hydro-solvent N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) is formed. For hyperthermic treatment of patients, NPs can also be coordinated to an organ, tissue, or tumor via an external attractive field. Given the increasing interest in iron NPs, the purpose of this review is to present data from iron oxide nanoparticles specially chitosan-capped iron NPs for different biomedical fields.
... Similarly, chitosan offers wide possibilities for the manufacture of molecularly imprinted adsorbents (MIA) (Xu et al., 2015;Karrat et al., 2020), whose preparation consists of using chitosan, or its composites, as a matrix for the prior moulding of an adsorbate of interest (usually molecules or ions but which can also be applied to viruses, bacteria, proteins, etc.) and whose subsequent extraction generates an adsorbent of very high specificity because its active sites have the shape of the adsorbate. Despite this, MIAs have been little exploited as adsorbents, especially in the oenological area, although some interesting studies have been reported in related applications, such as the removal of the toxin patulin in pear juices using a molecularly imprinted adsorbent that additionally possesses magnetic properties (Sun et al., 2020). ...
This paper reviews the main applications of the biopolymer chitosan, the main derivative of chitin, a material usually obtained from natural sources accessible at low cost, i.e., industrial wastes from fisheries. Due to its natural origin, which confers biodegradability and biocompatibility properties, in addition to its low toxicity, chitosan has been gaining attention in numerous sectors, such as agriculture, food, medicine, pharmaceuticals, etc., including also important oenological applications due to its potential as a green alternative to the use of sulphite. Among the many applications that can be generated from these materials in the wine-making area, their use has been reported for the clarification of must; in the preparation of films for the removal of contaminants, whether organics such as ochratoxin A or inorganics such as some metal ions and their salts; the control of turbidity caused by protein precipitation; the encapsulation of yeasts of oenological interest and enzymes for the control of adverse microorganisms such as Brettanomyces; the manufacture of sensors and nanosensors for the quantification of contaminants, the quality control of starting materials and final products, the optimisation of fermentation processes, the monitoring of storage conditions, etc. As a result of this review, significant development of the applications of this material in the oenological area can be expected, especially due to the possibilities of preparing new derivatives, including the great variety of these that have been recently proposed through click reactions, as well as the growing incursion of chitosan in nanobiotechnology.
... It affects the reproducibility of the analysis, and thus ultimately compromises the accuracy and precision of the assay. Chitosan is a natural biopolymer widely used for the preparation of sensors and biosensors due to its capacity of providing a suitable environment for the immobilization of different reagents including biological compounds [21]. In 2018, Wang et al. reported the immobilization of chitosan followed by two layers of chromogenic reagents and horseradish peroxidase (HRP) onto the paper to detect uric acid and glucose in serum samples [22]. ...
The traditional analytical methods used for biomedical analysis are expensive and not easy to handle and require sophisticated instruments, thus their application is limited in resource-limited settings. Due to their portability, low cost, and ability to be applied to different analytical techniques, paper-based analytical devices are becoming valuable tools for biomedical analysis. The integration of smartphones into analytical devices has provided the ability to build portable, cost-effective, straightforward analytical devices for biomedical analysis and mobile health. The key aim of this review is to emphasize the recent applications of PADs combined with a smartphone for the optical analysis of biomedical species. We started this review by highlighting the type of papers and their modifications with different materials to prepare the PADs. After that, this review presents various detection methods including colorimetry, fluorescence, and luminescence where the smartphone is used for read-out. In the end, we provided the recent applications of the analysis of different biomedical compounds such as cancer and cardiovascular biomarkers, metal ions, glucose, viruses, etc. We believe that the present review will attract a wide scientific community in the areas of analytical chemistry, sensors, and clinical testing.
... Chitosan is a biopolymer obtained from chitin by deacetylation reaction. It is widely used in the analytical field [36][37][38] because of its interesting properties including biodegradability [39], film-forming ability [40,41], and free amines groups. For example, Kim et al. [42] reported a two-dimensional μPAD based on chitosan for the determination of glucose from whole blood. ...
Bisphenol-A (BPA) is defined as one of the endocrine disrupting compounds. The accurate and inexpensive colorimetric paper-based analytical devices (PADs) are of crucial importance for BPA analysis. In this context, we developed for the first time a new PAD modified with chitosan and sulfamethoxazole (Chitosan-PAD) for the visual detection of BPA in water. The PAD was characterized by Fourier-transform infrared spectroscopy, which confirmed its modification by the func-tionalized chitosan. A yellow coloration was developed when a small volume of BPA was added to the Chitosan-PAD, allowing for visual and smartphone detection. This new strategy is based on a specific combination of BPA with chitosan and sulfamethoxazole that provides a hight selectivity to the Chitosan-PAD. The proposed PAD was successfully employed in combination with a pre-concentration step for the detection of 0.01 µg mL− 1 of PBA with the naked eye using a 10-fold precon-centration factor. The PAD was effectively applied for BPA quantification in water samples with good recoveries. The developed PAD provides a green and cost-effective strategy for the on-site and one-step detection of BPA in water samples.
... [22] In addition, it is more reported in imprinted chitosan-based sorbents especially prepared employing sol-gel technique. [23] Optical properties Chitosan (Table 1) is non chromophore compound, that exhibits weak UV absorption at 200 nm, due to n-p à transitions. [36] However, it can act as a support matrix, where the free amino group can react with several dyes through schiff's base formation. ...
Biomass and biowastes stand as sustainable and cost-effective environmentally benign alternative feedstock. Chitosan is a biocompatible, bioactive, and biodegradable biopolymer derived from chitin to achieve eight aspects out of the 12 green chemistry principles. Chitosan got significant attention in several fields including chemical analysis, in addition to chemical functionally, which enabled its use as adsorbent and its structural crosslinking using various crosslinkers. The physicochemical, technological, and optical properties of chitosan have been extensively exploited in analysis. Mainly, deacetylation degree and molecular weight are controlling its properties and hence controlling its functions. This review presents a structure, properties, and functions relationships of chitosan. It also aims to provide an overview of the different functions that chitosan can serve in each analytical technique such as supporting matrix, catalyst…etc. The contribution of chitosan in improving the ecological performance is discussed in each technique.
... Molecularly imprinted polymers (MIPs), also known as artificial antibodies, are materials possessing selective recognition sites that can bind the desired molecule [15,16]. From a very simple point of view, the fingerprints can find parallelism with molecules since each one has its imprint with a specific size, functional group, and shape [17]. ...
In this work, we developed a paper-based analytical device (PAD) that utilizes molecularly imprinted polymer (MIP) as the biomimetic receptor and a very simple colorimetric assay combined with a smartphone readout. Sulfamethoxazole was used as a model analyte to evaluate the feasibility of the developed MIP-PAD. After the synthesis of MIP, its adsorption properties (isotherm, kinetic and thermodynamic) were scrutinized. Thereafter, The MIP- PAD was fabricated through the vacuum-assisted deposition of MIP suspension onto porous paper forming a 7 mm diameter of MIP layer. The MIP-PAD was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. The sulfamethoxazole transforms into azo dye through a colorimetric reaction. The smartphone was utilized for the read-out of results. The LOD was 0.21 ppm. The proposed MIP-PAD showed high long-term stability. The determination of SMX was carried out in spiked tap and river water samples to evaluate the applicability of the proposed analytical strategy in real-world applications. The developed MIP-PAD would provide a new platform for real-time, selective, rapid, user-friendly, low-cost, portable, and straightforward colorimetric assays in environmental monitoring, public health, and food control.
... Nucleophilic reactions on electrophilic carbons such as aldehydes, ketones and carboxylic acids are thus made possible by the non-binding nucleophilic doublet possessed by the primary amine. The use of chitosan in the MIP matrix is increasingly widespread and the number of published works reporting the extent of research in this area is constantly expanding (Karrat et al., 2020;Zouaoui et al., 2020a). Chitosan combined with the MIP technique have been reported for the preparation of the electrochemical sensors for different target molecules including pharmaceutical compounds (Lin et al., 2015;Song et al., 2019), protein (Fatoni et al., 2014;Xia et al., 2016), sweet , phenolic compounds (Deng et al., 2013;Li et al., 2013;Chakroun Galai et al., 2020;Salvo-Comino et al., 2020), organic compounds , ions , and pesticides (Zouaoui et al., 2020a). ...
... Sensors are devices that allow detecting or measuring a physical property and responding to it. Sensors can be MIP is a material polymer containing specific cavities (imprints) to selectively adsorb the target analyte, hence mimicking the immune system through the recognition process of antibody-antigen ( Fig. 2) [3,4]. The MIP is usually produced by polymerizing a suitable monomer in the presence of a template followed by the extraction of the template, leaving behind specific imprints [5,6]. ...
Cancer and cardiovascular diseases have become one of the leading causes of death worldwide. Therefore, early detection of these diseases and rapid intervention by medical staff remain a great challenge for clinicians and healthcare providers worldwide. Cancer and cardiovascular disease biomarkers are promising tools for early diagnosis of the disease before it becomes incurable at an advanced stage. They also contribute to monitoring the progress of therapy and surgical treatment. Indeed, sensors have shown great importance for the detection of cancer and cardiovascular biomarkers. Sensors usually require a recognition element for the selective detection of targets. Molecularly imprinted polymer (MIP), as an artificial antibody, has been proposed as an alternative recognition element in sensing fields to overcome the main drawbacks of natural antibodies. With the high need for sensors providing results in a short time and making easier the early diagnosis of these diseases, MIP-based sensors are attracting considerable interest recently, which will undoubtedly be increased in the future due to the sustainability trend. The key aim of this review is to emphasize the recent applications of sensors based on MIP for the detection of cancer and cardiovascular biomarkers and to highlight the key advances related to MIP-based sensors. Furthermore, several key future trends about the applications of MIP-based sensors for the detection of cardiovascular and cancer biomarkers are presented.
... The MIP is usually prepared by means of the creation of a template-monomer complex followed by polymerization in presence of a suitable cross-linker and initiator. Afterward, the template is extracted to leave behind imprints that correspond to the form, size, and functional groups of the template [16][17][18]. The selection of monomer and porogen solvent is a crucial factor to achieve good affinity. ...
A new theoretical approach based on density functional theory was developed to find the most suitable monomer and porogen solvent to design a specific molecularly imprinted polymer (MIP) for bisphenol-A (BPA). Various theoretical investigations were carried out including HOMO and LUMO calculation, molecular electrostatic potential of the BPA-monomer interactions, and selection of the optimal monomer and porogen solvent using binding energies of BPA-monomer. Besides, counterpoise correction was used to avoid the problem of basis set superposition error. The theoretical results demonstrated that among virtual monomers, methacrylic acid and acrylamide showed good affinity towards BPA. The optimization of solvents was done using the polarizable continuum model and it was found that acetone was the most appropriate solvent. According to the obtained theoretical approach results, magnetic MIP (magMIP) was prepared using a high-power ultrasound probe. Scanning/transmission electron microscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, and X-ray diffraction were used to characterize the as-prepared magMIP. Adsorption behavior was explained by Sips and pseudo-second-order models for isotherm and kinetic studies, respectively. Furthermore, magMIP showed favorable adsorption selectivity for BPA over other phenolic compounds. Finally, the developed magMIP was successfully used as a sorbent in solid-phase extraction combined with an electrochemical sensor for the detection of BPA. The obtained limit of detection was 66 nM and the recovery values in tap water sample were 104 and 105.5% for 2 and 10 µM, respectively, with RSD values lower than 5 % (n = 3).
... As an important developmental direction of molecular imprinting technology (24)(25)(26), metal ion imprinting technology (27) has vital academic and application value in various fields of environment and material science (28)(29)(30)(31)(32), for instance, solid phase extraction (33), sensor (34)(35)(36), membrane separation (37), etc. The concept of ion imprinting technology is that metal ion is used as template to form a chelate by combining with monomer through electrostatic and coordination actions. ...
In this study, a novel functional monomer N-(1-(2,4-difluorophenyl)-2-(1H-1,2,4-triazol-1-yl)ethyl)acrylamide (NDTEA) was designed and synthesized, and was used to prepare Ni(ii) ion-imprinted polymers (Ni(ii)-IIPs). Sixteen kinds of Ni(ii)-IIP (Ni(ii)-IIP1–16) and corresponding non-imprinted polymers (NIP1–16) were prepared by precipitation polymerization method. After optimized condition experiment, Ni(ii)-IIP5 possessed maximum adsorption capacity and better imprinting factor under optimal experimental conditions which indicated by equilibrium adsorption experiments. The morphology and structural characteristics of Ni(ii)-IIP5 were characterized by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET). The adsorption selectivity of Ni(ii)-IIP5 was analyzed by ICP-OES, and the results showed that Ni(ii)-IIP5 had favorable selectivity recognition ability for Ni(ii) when Cu(ii), Co(ii), and Cd(ii) are used as competitive ions. The kinetic experiment indicated that the performance of Ni(ii) adsorption on the surface of Ni(ii)-IIP5 obeyed the pseudo-first-order model, and adsorption equilibrium was attained after 15 min. Isothermal adsorption process fitted to Langmuir and Freundlich isothermal adsorption models, simultaneously. The results showed that Ni(ii)-IIP5 prepared by using a new functional monomer had better permeation selectivity and higher affinity for Ni(ii), which also verified the rationality of the functional monomer design. At the same time, it also provided a broad application prospect for removal of Ni(ii) in complex samples.
... The template leaves behind after its removal complementary cavities to its shape, size, and chemical structure [24]. MIPs present various advantages such as high selectivity, fast preparation, low cost, and chemical stability [25,26]. MIPs have been applied for various types of analytes such as viruses [27], bacteria [28], emerging pollutants [29], pharmaceutical drugs [30,31], protein [32], and pesticides [33]. ...
A selective, rapid and simple method based on magnetic molecularly imprinted polymer (MMIP) as adsorbent was developed for the extraction, preconcentration, and determination of bisphenol A (PBA) in water samples. The adsorption experiments showed that the adsorption capacity of MMIP for BPA was much higher than magnetic molecular non imprinted polymers (MNIP). The MMIP exhibited an excellent selectivity towards BPA over other interfering phenols. In addition , it was successfully applied as an adsorbent in solid-phase extraction (SPE) coupled to a spectrophotometric method. Various parameters affecting the SPE of BPA by the MMIP were investigated, such as the elution solution, the amount of MMIP, and the extraction time. The spectrophotometric method is based on the optimization of the coupling reaction between BPA and a diazo compound to produce a yellow-colored product that absorbs at the wavelength of 446 nm. A linear response for the determination of BPA was achieved in the concentration range of 0.1-3.4 µg mL-1 of BPA. The limit of detection and limit of quantification for BPA were 0.03 µg.mL-1 and 0.1 µg mL-1, respectively. The developed procedure was successfully applied for BPA determination in spiked tap, mineral, and wastewaters samples with satisfactory recoveries. A preconcentration factor of 200 was achieved in by this method allowing the determination of 0.0025 µg/ mL-1 BPA in water samples. Furthermore, the developed MMIP showed good reproducibility and stability for BPA detection.
... The template leaves behind after its removal complementary cavities to its shape, size, and chemical structure [24]. MIPs present various advantages such as high selectivity, fast preparation, low cost, and chemical stability [25,26]. MIPs have been applied for various types of analytes such as viruses [27], bacteria [28], emerging pollutants [29], pharmaceutical drugs [30,31], protein [32], and pesticides [33]. ...
A selective, rapid and simple method based on magnetic molecularly imprinted polymer (MMIP) as adsorbent was developed for the extraction, preconcentration, and determination of bisphenol A (PBA) in water samples. The adsorption experiments showed that the adsorption capacity of MMIP for BPA was much higher than magnetic molecular non imprinted polymers (MNIP). The MMIP exhibited an excellent selectivity towards BPA over other interfering phenols. In addition, it was successfully applied as an adsorbent in solid-phase extraction (SPE) coupled to a spectrophotometric method. Various parameters affecting the SPE of BPA by the MMIP were investigated, such as the elution solution, the amount of MMIP, and the extraction time. The spectrophotometric method is based on the optimization of the coupling reaction between BPA and a diazo compound to produce a yellow-colored product that absorbs at the wavelength of 446 nm. A linear response for the determination of BPA was achieved in the concentration range of 0.1-3.4 µg mL⁻¹ of BPA. The limit of detection and limit of quantification for BPA were 0.03 µg mL⁻¹ and 0.1 µg mL⁻¹, respectively. The developed procedure was successfully applied for BPA determination in spiked tap, mineral, and waste waters samples with satisfactory recoveries. A preconcentration factor of 200 was achieved by this method allowing the determination of 0.0025 µg mL⁻¹ BPA in water samples. Furthermore, the developed MMIP showed good reproducibility and stability for BPA detection.
... Nucleophilic reactions on electrophilic carbons such as aldehydes, ketones and carboxylic acids are thus made possible by the non-binding nucleophilic doublet possessed by the primary amine. The use of chitosan in the MIP matrix is increasingly widespread and the number of published works reporting the extent of research in this area is constantly expanding (Karrat et al., 2020;Zouaoui et al., 2020a). Chitosan combined with the MIP technique have been reported for the preparation of the electrochemical sensors for different target molecules including pharmaceutical compounds (Lin et al., 2015;Song et al., 2019), protein (Fatoni et al., 2014;Xia et al., 2016), sweet (Li et al., 2014), phenolic compounds (Deng et al., 2013;Li et al., 2013;Chakroun Galai et al., 2020;Salvo-Comino et al., 2020), organic compounds (Chen et al., 2011), ions (Wu et al., 2020), and pesticides (Zouaoui et al., 2020a). ...
A novel electrochemical impedance spectroscopy (EIS) microsensor was implemented for the dosage of traces of glyphosate, in real and synthetic water samples. Molecularly imprinted chitosan was covalently immobilized on the surface of the microelectrode previously modified with 4-aminophenylacetic acid (CMA). The characterization of the resulting microelectrodes was carried out by using cyclic voltammetry measurement (CV), scanning electron microscopy (SEM), and electrochemical impedance spectrometry (EIS). EIS responses of the CS-MIPs/CMA/Au microsensor toward GLY was well-proportional to the concentration in the range from 0.31 × 10⁻⁹ to 50 × 10⁻⁶ mg/mL indicating a good correlation. The detection limit of GLY was 1 fg/mL (S/N = 3). Moreover, this microsensor showed good reproducibility and repeatability, high selectivity, and can be used for the detection of GLY in river water.
... Ion imprinted polymers (IIPs) constitute a new class of sorbents possessing selectivity and affinity for the separation, pre-concentration or removal of target ions [14,16,[19][20][21]. IIPs are prepared by the formation of specific recognition sites in the framework of organic polymers and usually prepared by the bulk polymerization method [16,22]. ...
A biomimetic, ion-imprinted polymer (IIP) was prepared by electropolymerization of pyrrole at the surface of gold electrodes decorated with vertically grown ZnO nanorods. The vertical growth of the nanorods was achieved via an ultrathin aryl monolayer grafted by reduction of diazonium salt precursor. Pyrrole was polymerized in the presence of L-cysteine as chelating agent and Hg2+ (template). Hg2+ imprinted polypyrrole (PPy) was also prepared on a bare gold electrode in order to compare the two methods of sensor design (Au-ZnO-IIP vs. Au-IIP). Non-imprinted PPy was prepared in the same conditions but in the absence of any Hg2+ template. The strategy combining diazonium salt modification and ZnO nanorod decoration of gold electrodes permitted us to increase considerably the specific surface area and thus improve the sensor performance. The limit of detection (LOD) of the designed sensor was ~1 pM, the lowest value ever reported in the literature for gold electrode sensors. The dissociation constants between PPy and Hg2+ were estimated at [Kd1 = (7.89 ± 3.63) mM and Kd2 = (38.10 ± 9.22) pM]. The sensitivity of the designed sensor was found to be 0.692 ± 0.034 μA.pM-1. The Au-ZnO-IIP was found to be highly selective towards Hg2+ compared to cadmium, lead and copper ions. This sensor design strategy could open up new horizons in monitoring toxic heavy metal ions in water and therefore contribute to enhancing environmental quality.
... Ion imprinted polymers (IIPs) constitute a new class of sorbents possessing selectivity and affinity for the separation, pre-concentration or removal of target ions [14,16,[19][20][21]. IIPs are prepared by the formation of specific recognition sites in the framework of organic polymers and usually prepared by the bulk polymerization method [16,22]. ...
A biomimetic, ion-imprinted polymer (IIP) was prepared by electropolymerization of pyrrole at the surface of gold electrodes decorated with vertically grown ZnO nanorods. The vertical growth of the nanorods was achieved via an ultrathin aryl monolayer grafted by reduction of diazonium salt precursor. Pyrrole was polymerized in the presence of L-cysteine as chelating agent and Hg2+ (template). Hg2+-imprinted polypyrrole (PPy) was also prepared on a bare gold electrode in order to compare the two methods of sensor design (Au-ZnO-IIP vs. Au-IIP). Non-imprinted PPy was prepared in the same conditions but in the absence of any Hg2+ template. The strategy combining diazonium salt modification and ZnO nanorod decoration of gold electrodes permitted us to increase considerably the specific surface area and thus improve the sensor performance. The limit of detection (LOD) of the designed sensor was ~1 pM, the lowest value ever reported in the literature for gold electrode sensors. The dissociation constants between PPy and Hg2+ were estimated at [Kd1 = (7.89 ± 3.63) mM and Kd2 = (38.10 ± 9.22) pM]. The sensitivity of the designed sensor was found to be 0.692 ± 0.034 μA.pM-1. The Au-ZnO-IIP was found to be highly selective towards Hg2+ compared to cadmium, lead and copper ions. This sensor design strategy could open up new horizons in monitoring toxic heavy metal ions in water and therefore contribute to enhancing environmental quality.
... Ion imprinted polymers (IIPs) constitute a new class of sorbents possessing selectivity and affinity for separation or preconcentration or removal of target ion s [14,16,[19][20][21]. IIPs are prepared by formation of specific recognition sites in the framework of organic polymers and usually prepared by bulk polymerization method [16,22]. ...
A biomimetic, ion-imprinted polymer (IIP) was prepared by electropolymerization of pyrrole at the surface of gold electrodes decorated with vertically grown ZnO nanorods. The vertical growth of the nanorods was achieved via an ultrathin aryl monolayer grafted by reduction of diazonium salt precursor. Pyrrole was polymerized in the presence of L-cysteine as chelatant agent and Hg(II) (template). Hg(II)-imprinted polypyrrole (PPy) was also prepared on bare gold electrode in order to compare the two methods of sensor design (Au-ZnO-IIP vs Au-IIP). Non-imprinted PPy was prepared in the same conditions, however in the absence of any Hg2+ template. The strategy combining diazonium salt modification and ZnO nanorod decoration of gold electrodes permitted to increase considerably the specific surface and thus to improve the sensor performances. The limit of detection (LOD) of the designed sensor was ~1 pM, the lowest value ever reported in literature. The dissociation constants between PPy and Hg2+ were estimated at [Kd1 = (7.89 ± 3.63) mM and Kd2 = (38.10 ± 9.22) pM]. The sensitivity of the designed sensor was found to be 0.692 ± 0.034 μA/pM. The Au-ZnO-IIP was found to be highly selective towards Hg(II) compared to cadmium, lead and copper ions. This sensor design strategy could open up new horizons in monitoring toxic heavy metal ions in water and therefore contribute to enhance environmental quality.
We have developed a ratiometric fluorescence sensor for detecting dopamine (DA) using a silica-based molecular imprinting polymer (MIP) coated on cabbage-derived blue emissive carbon quantum dot (CQD) and deposited on optical fiber. Physicochemical characterization confirmed the successful integration of MIP and CQD, which created the selective lossy mode resonance (LMR) for DA monitoring. The experimental factors were optimized to obtain the maximum responses, and the sensing probe displays a dynamic response range of 0.3–
$100 \mu \text {m}$
and detection limit
$0.027 \mu \text {m}$
. This strategy was successfully applied to detect DA in red wine, coffee, apple, orange, and broad bean juices samples, with negligible cross-reactivity toward other potential interfering species (e.g., epinephrine, ascorbic acid, and uric acid). This novel rotational optical fiber-based sensor has promising potential and versatility for point-of-care, portable, and on-site sensing of environmental and biological samples.
Molecularly imprinted polymers (MIPs) are well-known for their enhanced selectivity and affinity for specific targets even in complex matrices. As such, MIPs have been widely employed in various areas such as sensing, catalysis, and drug delivery applications. Considering the limitations of conventional synthesis approaches for MIPs (e.g., use of organic solvents and their release into the environment), the use of new cleaner synthetic strategies based on the principles of green chemistry and engineering has become more important in terms of the control of morphology, uniformity of the binding sites, and the exclusion of organic solvents. This article has been organized to describe the environmentally friendly features of imprinted materials along with their promising prospects toward sorptive extraction and sensing technologies (e.g., electrochemical/optical sensors). The current challenges in this research field as well as future perspectives are also highlighted.
There is a trend in analytical chemistry towards development of eco-friendly methods of sample preparation without loss of efficiency. This book provides a general, critical, and updated vision of the different green sample preparation approaches that have been developed. These include miniaturisation of the extraction techniques that allow a reduction not only of the chemicals used during the process, but also of the sample amount; the use of greener solvents, such as certain ionic liquids (ILs) or deep eutectic solvents (DES), instead of conventional organic solvents; and the use of new selective sorbent materials that allow both extraction and clean-up in the same step. All of these strategies have been successfully applied to the determination of a wide variety of organic and inorganic compounds.
Advanced undergraduate and graduate students will find this book a good reference source and, because of the multidisciplinary nature of this topic, it will be of use to a broad audience including chemists, materials scientists, environmental analysts, forensic scientists, pharmacists, biologists and chemical engineers, who are involved and interested in the future frontiers of analytical chemistry.
The use of porous materials as the core for synthesizing molecularly imprinted polymers (MIPs) adds significant value to the resulting sensing system. This review covers in detail the current progress and achievements regarding the synergistic combination of MIPs and porous materials, namely metal/covalent–organic frameworks (MOFs/COFs), including the application of such frameworks in the development of upgraded sensor platforms. The different processes involved in the synthesis of MOF/COF-MIPs are outlined, along with their intrinsic properties. Special attention is paid to debriefing the impact of the morphological changes that occur through the synergistic combination compared to those that occur due to the individual entities. Thereafter, the strategies used for building the sensors, as well as the transduction modes, are overviewed and discussed. This is followed by a full description of research advances for various types of MOF/COF-MIP-based (bio)sensors and their applications in the fields of environmental monitoring, food safety, and pharmaceutical analysis. Finally, the challenges/drawbacks, as well as the prospects of this research field, are discussed in detail.
Chitosan, a biofriendly material, has a wide range of applications owing to its biocompatibility and biodegradability. We successfully prepared super-adsorbent membranes by dip-coating filter paper in chemically and physically modified chitosan solutions, and compared the urea adsorption performances of the different chitosan membranes. Chemical modification was achieved by successfully introducing carboxyl and amine groups into chitosan by carboxylation and amination using chloroacetic acid (ClCH₂CO₂H) and ethylenediamine (C2H4(NH2)2), respectively. Physical modification was performed by attempting different crosslinking reactions using sodium tripolyphosphate and copper ions (Cu²⁺). The effects of the various physical and chemical modifications was determined on the urea reduction ratio (URR). At a urea concentration of 500 ppm, the modified chitosan membranes exhibited URRs of >80 % within 2 h, a 38 % decrease in the equilibrium swelling ratio, and a 600 % increase in the bursting strength. These results demonstrate the immense potential of these membranes for hemodialysis in biomedical research. Lastly, model fitting revealed that the mechanisms of urea adsorption onto chitosan were best described using the Freundlich adsorption isotherm and the pseudo-second-order kinetic model.
Molecularly imprinted polymers that mimic the binding mechanism of antibodies and their antigens exhibit several advantages, such as fast synthesis, low cost, high stability, and allow to overcome the ethical issues associated with antibody farming in animals. Herein, a novel strategy combining the magnetic molecularly imprinted polymer (MMIP) as an artificial antibody with a fluorescence procedure for the detection of quercetin in plant samples was designed. The MMIP was synthesized via a radical polymerization process to recognize specific functional groups of quercetin using a green technique based on high energy ultrasound irradiation. The developed MMIP was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning/transmission electron microscopy, and thermal gravimetric analysis, which confirmed the successful preparation of MMIP. The adsorption capacity and selectivity of the MMIP for quercetin and other interferents analogous were performed. The MMIP was applied in the solid-phase extraction (SPE) technique as a selective sorbent for the sample preparation. Besides, a sensitive fluorometric method for the quantitation of quercetin was developed. A linear response was obtained within the concentration of 0.005–1.25 μg mL⁻¹ of quercetin. The limit of detection and quantitation were 1.1 ng mL⁻¹ and 3.7 ng mL⁻¹, respectively. The average recoveries for quercetin were between 92.2% and 104.7% with an RSD less than 5.06% in spiked orange juice and tea extract samples. Furthermore, the developed procedure was successfully combined with a new paper-based analytical device for on-site smartphone analysis of quercetin.
Magnetic nanoparticles (MNPs) uniquely combine superparamagnetic performance with dimensions that are smaller than or similar size to molecular analytes. Recently, functionalized MNPs are predicted to be a driver for technology and business in this century and hold the promise of high performance materials that will significantly influence all aspects of society. Functionalized MNPs are creating new possibilities for development and innovation in different analytical procedures. Despite their participation in modern development, they are in their infancy and largely unexplored for their practical applications in analysis.
This book will provide quality research and practical guidance to analytical scientists, researchers, engineers, quality control experts and laboratory specialists. It covers applications of functionalized MNPs in all stages of analytical procedures. Their incorporation has opened new possibilities for sensing, extraction and detection enabling an increase in sensitivity, magnifying precision and improvement in the detection limit of modern analysis. Toxicity, safety, risk, and legal aspects of functionalized MNPs and the future of analytical chemistry with respect to their use is covered. The book provides an integrated approach for advanced analytical methods and techniques for postgraduates and researchers looking for a reference outlining new and advanced techniques surrounding the applications of functionalized nanomaterials in analytical chemistry.
A molecularly imprinted polymer/ Au nanoparticles-MoS2-graphene/GCE sensor was fabricated and used for the electrochemical detection of rutin. The rose-like Au nanoparticles-MoS2 -graphene composite (AuNPs-MoS2-GN) was fabricated by using a one-pot hydrothermal method. Graphene acted as an efficient matrix for the growth of MoS2 nanoflower (NF), and the edges of the MoS2 NF subsequently loaded AuNPs. The AuNPs-MoS2-GN composite had large specific surface area, good conductivity and high catalysis, and showed excellent electrochemical response to rutin. To improve the selectivity, rutin imprinted chitosan film was electrodeposited on the AuNPs-MoS2-GN/GCE. The obtained molecularly imprinted sensor had strong adsorption capacity for rutin. Under the optimized conditions, the sensor showed a low detection limit (i.e. 4 nmol L⁻¹) and a wide detection range (i.e. 0.01−45.0 μmol L⁻¹). It also displayed high stability and selectivity. When the sensor was applied to the determination of rutin in real samples satisfactory results were achieved.
The development of novel biocompatible and cost effective cryogel membrane which shows enhanced antimicrobial properties in order to use for several approaches such as wound dressing, scaffold or food packaging was aimed in this study. A super macro porous lysozyme imprinted cryogel membranes showing antibacterial effect against both Gram-positive and Gram-negative bacteria were prepared by using molecular imprinting technique. N-methacryloyl-(L)-histidine methyl ester (MAH) was used as the pseudo specific ligand and complexed with Cu⁺⁺ in order to provide metal ion coordination between MAH and template molecule (lysozyme). Comparing the antibacterial activity of different lysozyme concentrations, cryogel membranes were prepared in three different concentrations. To synthesize Poly (hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine methylester) P(HEMA-MAH) cryogel membrane, free radical polymerization initiated by N, N, N′, N′-tetramethylene diamine (TEMED) and ammonium persulfate (APS) was carried out at −12 °C. The characterization of the lysozyme imprinted cryogel membrane was accomplished by using scanning electron microscopy (SEM), swelling degree measurements and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) spectroscopy. The cytotoxicity test of produced membrane was performed by using mouse fibroblast cell line L929. The antibacterial activity of P(HEMA-MAH) lysozyme molecular imprinted [P(HEMA-MAH) Lyz-MIP] cryogel membranes against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were determined by Kirby-Bauer membranes diffusion and viable cell counting methods. When the antibacterial effect of P(HEMA-MAH) Lyz-MIP cryogel membranes were evaluated, it was found that P(HEMA-MAH) Lyz-MIP cryogel membranes had stronger antibacterial effects against Gram-negative E. coli bacteria even in low lysozyme concentrations. In addition, 100% bacterial inhibition was detected for both of two bacteria at increasing lysozyme concentrations.
As the demand for portable, selective yet sensitive environmental pollutants monitoring devices increases, electrochemical sensors specifically screen printed electrodes (SPEs) integrated with molecularly imprinted polymer layers are gaining unprecedented attention. The work reported herein demonstrates a successful adaptation of an antibiotic imprinted polymer from one platform to another of different sensing principles, without compromising its performance. Specifically, sulfamethizole-MIP (SMZ-MIP) previously optimized on a surface acoustic wave (SAW) platform is redesigned on SPE with necessary upgrade to achieve a portable and highly-performing cost-effective electrochemical sensor for detecting sulfamethizole (SMZ) in water. Sensor performance, as analysed by differential pulse voltammetry (DPV) electrochemical technique indicates rapid response, good sensitivity as represented by an LOD of 0.9 nM, and LOQ of 3 nM; excellent selectivity, as well as concentration dependent responses both in buffer and tap water samples. This study indicates a significant step towards achieving the desired commercially viable small molecule detection platform that combines important peculiarity of low cost, ease of operation, portability and on-site utilization in environmental water.
In this work, we present a novel study on the development of an electrochemical biomimetic sensor to detect the ciprofloxacin (CIP) antibiotic. A chitosan gold nanoparticles decorated molecularly imprinted polymer (Ch-AuMIP) was used to modify the glassy carbon electrode (GCE) for preparation of the sensor. The Ch-AuMIP was characterized to understand various properties like chemical composition, morphology, roughness, and conduction using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and cyclic voltammetry (CV) respectively. Several experimental conditions affecting the Ch-AuMIP/GCE sensor such as the CIP removal agent, the extraction time, the volume of Ch-AuMIP drop-cast onto GCE and the rebinding time were studied and optimized. The Ch-AuMIP sensor sensitivity was studied in the concentration range of 1–100 μmol L⁻¹ exhibiting a limit of detection of 210 nmol L⁻¹. The synergistic combination of Au nanoparticles and Ch-MIP helps detect the CIP antibiotic with good sensitivity and selectivity, respectively. We investigated the selectivity aspect by using some possible interfering species and the developed sensing system showed good selectivity for CIP with a 66% response compared to the other compounds (≤45% response). The proposed sensing strategy showed its applicability for successful detection of CIP in real samples like tap water, mineral water, milk, and pharmaceutical formulation. The developed sensor showed good selectivity towards CIP even among the analogue molecules of Norfloxacin (NFX) and Ofloxacin (OFX). The developed sensor was successfully applied to determine the CIP in different samples with a satisfactory recovery in the range of 94 to 106%.
Phenolic compounds such as catechol are present in a wide variety of foods and beverages; they are of great importance due to their antioxidant properties. This research presents the development of a sensitive and biocompatible molecular imprinted sensor for the electrochemical detection of catechol, based on natural biopolymer-electroactive nanocomposites. Gold nanoparticle (AuNP)-decorated multiwalled carbon nanotubes (MWCNT) have been encapsulated in a polymeric chitosan (CS) matrix. This chitosan nanocomposite has been used to develop a molecular imprinted polymers (MIP) in the presence of catechol on a boron-doped diamond (BDD) electrode. The structure of the decorated MWCNT has been studied by TEM, whereas the characterization of the sensor surface has been imaged by AFM, demonstrating the satisfactory adsorption of the film and the adequate coverage of the decorated carbon nanotubes on the electrode surface. The electrochemical response of the sensor has been analyzed by cyclic voltammetry (CV) where excellent reproducibility and repeatability to catechol detection in the range of 0 to 1 mM has been found, with a detection limit of 3.7 × 10−5 M. Finally, the developed sensor was used to detect catechol in a real wine sample.
A voltammetric sensor for bisphenol A (BPA) detection was developed. It was based on a gold electrode modified by an electrodeposited molecularly imprinted chitosan (CS) film. Fourier Transformed Infrared spectroscopy, scanning electron microscopy and electrochemistry were used to characterize and compare the surface of the molecularly imprinted polymer (MIP) and non-molecularly imprinted polymer (NIP) films. The analytical performance of this biosensor was then established using square wave voltammetry (SWV) of the ferro/ferricyanide redox probe, in the range of −300 and 600 mV. The oxidation peak current was proportional to the logarithm of BPA concentration in the range between 10⁻³ M to 10⁻²¹ M with a limit of detection of 0.67 × 10⁻²¹ M. The elaborated sensor showed good repeatability (RSD 2.08%), reusability and recognition of BPA in the presence of similar structural moieties. The proposed sensors were successfully employed to determine BPA in real plastic bottles for drinking water.
The authors describe an electrochemical method for the determination of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). It is based on the use of a molecularly imprinted polymer (MIP) and of dsDNA as a bio-specific substance. The modified electrode was prepared by electropolymerization of ortho-phenylenediamine (oPD) in the presence of DNA and of 2,4-D (the template). The imprinted MIP was placed on a pencil graphite electrode (PGE) modified with chitosan and multiwalled carbon nanotubes (MWCNTs). The template was removed with 0.4 M NaOH. The interaction of DNA with 2,4-D leads to its adsorption on the electrode, and this increases the sensitivity and selectivity of the method. After rebinding 2,4-D, the decrease in the peak current of oxidation of iron(II) acting as an electrochemical redox probe was measured by differential pulse voltammetry (DPV). The current, typically measured at around 0.5 V, increases linearly in the 0.01 to 10 pM 2,4-D concentration range, and the detection limit is 4.0 fM. The method is highly selective for 2,4-D. The modified electrode was applied to quantify 2,4-D in spiked environmental water and soil samples and gave absolute recoveries varying from 91.5 to 109.0%.
Graphical abstractSchematic representation of the fabrication of an electrochemical sensor for determination of 2,4-dichlorophenoxyacetic acid (2,4-D). Initially, the electrode was modified with chitosan and MWCNTs and then a composite was formed on it consisting of ortho-phenylenediamine (oPD), DNA and 2,4-D.
In this work, a comparative study of the effect of various solvents on the synthesis of magnetic molecularly imprinted polymers (MMIPs) based on the use of high-power ultrasound probe is reported for the first time. Dimethylsulfoxide (DMSO), dimethylformamide (DMF), ethanol, acetonitrile and acetone were studied as solvents for the synthesis of MMIPs. Several crucial experimental conditions such as the time of synthesis and the applied amplitude were investigated. DMSO, DMF and ethanol were successfully used for ultrasound-assisted synthesis of MMIPs. However, for the polymerization performed using acetonitrile and acetone, no significant conversion to product was observed. Under optimal conditions for each solvent tested, the synthesized MMIPs were characterized using several techniques such as Scanning/Transmission Electron Microscopy (SEM and STEM modes), X-Ray Diffraction, Fourier Transform Infra-Red Spectroscopy, Thermal Gravimetric Analysis and Vibrating Sample Magnetometer system. The study of adsorption time of MMIPs showed that fast adsorption occurred due to the presence of specific imprinted sites on the surface. Moreover, isotherm study showed that the experimental equilibrium data fitted well with Freundlich model. The results of selectivity study indicated that MMIPs could selectively recognize the target molecule. Due to its high adsorption properties and easiness of preparation, MMIP-DMSO was used successfully as adsorbent material in solid-phase extraction coupled to a colorimetric method for sulfamethoxazole (SMX). After optimizing analytical conditions, a calibration plot was performed in the concentration range from 0.2 to 5 µg·mL-1 with limits of detection and quantitation of 0.06 and 0.2 µg·mL-1, respectively. The developed procedure was applied successfully for SMX determination in spiked tap and mineral waters showing satisfactory recoveries. Besides, reusability study demonstrated that MMIP could be reused at least 8 times keeping good binding capacity.
To improve the adsorption capacity of Cd(II) ions, Cd(II) ions were imprinted on the surface of aminoethyl chitosan (AECS), which was coated on Fe3O4@SiO2 nanoparticles. A novel magnetic Cd(II) ion-imprinted polymer (Cd(II)-IIP) was synthesized, characterized, and applied to the selective separation of Cd(II) ions from aqueous solution. The adsorption–desorption properties and selectivity of Cd(II)-IIP and a non-imprinted polymer (Cd(II)-NIP) were investigated. The optimum pH and equilibrium binding time were established at pH 6.0 and 60 min, respectively. Kinetics studies demonstrated that the adsorption process proceeded according to a pseudo-first or second order model, while the adsorption isotherms agreed with the Langmuir model. The maximum adsorption capacities of Cd(II)-IIP and Cd(II)-NIP toward Cd(II) ions, as calculated by the Langmuir equation, at pH 6.0 and 25 °C were 26.1 and 6.7 mg/g, respectively. The imprinted polymer showed higher selectivity toward Cd(II) ions compared to the non-imprinted polymer. The relative selectivity factor (βr) values of Cd(II)/Cu(II), Cd(II)/Cr(II), and Cd(II)/Pb(II) were 3.315, 3.875, and 2.061, respectively. In addition, Cd(II) ions adsorbed on the Cd(II)-IIP adsorbent could be easily released using 0.1 M HNO3, thus showing good material stability and reusability. The adsorption capacity of Cd(II)-IIP was retained at 74% after undergoing six adsorption–desorption cycles.
pH and temperature dual‐sensitive protein imprinted microspheres with high absorption capacity have been successfully synthesized on the surface of SiO2 using chitosan grafted N‐isopropylacrylamide (CS‐g‐NIPAM) as the pH and temperature sensitive monomer, with acrylamide as comonomer, N,N′‐methylenebisacrylamide as the crosslinking agent and bovine serum albumin (BSA) as the template protein. The pH and temperature dual‐sensitivity was also investigated. The results showed that the adsorption capacity and imprinting factor improved slowly with increasing incubation pH from 4.6 to 7.0, and then decreased sharply in alkaline conditions due to the reduction of non‐specific binding from electrostatic and hydrogen bonding interactions. Fourier transform infrared spectroscopy, thermogravimetric analysis and transmission electron microscopy were used to characterize the polymers. The as‐prepared SiO2@BSA molecularly imprinted polymers were also found to have high adsorption capacity (119.88 mg g⁻¹) within 2 h, an excellent imprinting factor (α = 2.25), specific selectivity and good reusability. © 2019 Society of Chemical Industry
This review focuses on the recent achievement during period of 2013–2018 related to the electrochemical sensors based on molecularly imprinted polymers (MIPs) combined with nanomaterials for various kinds of applications. MIPs based electrochemical sensors have found a great interest due to their high stability, short time required for electropolymerization, and high specificity towards the target analyte. The sensitivity is considered as one of the important parameter in electrochemical sensing strategies that should be improved by the combination of highly conductive nanomaterials with selective MIPs. In general, the most employed nanomaterials are magnetic nanoparticles, gold nanoparticles (AuNPs), carbon nanotubes and graphene. This review discusses the main current achievement as well as the current challenges regarding the development of biomimetic sensors in electroanalysis.
Here, a molecularly imprinted – electrochemical quartz crystal microbalance (MIP-EQCM) sensor for aspartame is developed by grafting the aspartame-imprinted polymeric matrix of chitosan on gold coated quartz crystal electrode. Chitosan nanoparticles being biocompatible, biodegradable and also having large surface area provides a better platform by forming a well dispersed composite suspension with graphene. Additionally graphene facilitates direct electron transfer to electrode surface for electrochemical study because of having enhanced electrical conductivity. This EQCM-MIP sensor was characterized by atomic force microscopy (AFM), contact angle measurements, cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The obtained MIP showed high affinity to aspartame. A reliable method for analysis of aspartame in real and commercial samples was achieved by coupling EQCM-MIP with DPV. Linear relationship with R2 = 0.9749 (EQCM) and R2 = 0.9760 (DPV) on binding of aspartame at various concentrations was observed. Detection limit of 0.45 µg mL-1 (EQCM) and 0.07 µg mL-1 (DPV) of the fabricated sensor shows high sensitivity and high selectivity among various structural analogues of aspartame was also achieved. The improved detection limit is promising for determination of trace amount of aspartame. This demonstrates good memory capacity of this EQCM sensor. High recovery percentage and applicability of EQCM-MIP sensor in real matrices and commercial samples offers good potential for various applications.
A molecularly imprinted polymer (MIP) was fabricated for selective recognition of the highly persistent pollutant perfluorooctane sulfonate (PFOS). The MIP was prepared from chitosan and doped with fluorescent carbon quantum dots (CQDs). It was characterized by fluorescence spectrophotometry, scanning electron microscopy, and Fourier transform infrared spectroscopy. The fluorescence of the CQDs, best measured at excitation/emission wavelengths of 350/460 nm, is enhanced by PFOS, and the effect is much stronger for the MIP than for the nonimprinted polymer (NIP). The imprinting factor is 2.75. The method has good specificity over sodium dodecyl sulfate (SDS), perfluorooctanoic acid (PFOA), sodium dodecyl sulfonate (SDS’), sodium dodecyl benzene sulfonate (SDBS), perfluorooctanesulfonyl fluoride (POSF), perfluorobutane sulfonate (PFBS) and 1-octanesulfonic acid sodium (OSA). Fluorescence increases linearly in the 20–200 pg·L⁻¹ POSF concentration range in aqueous solution. The method was applied to the determination of PFOS in spiked serum and urine samples. The limits of detection are 66 and 85 pg·L⁻¹ for serum and urine samples respectively. The recoveries ranged from to 81–98%, with relative standard deviations in the range of 1.8–8.2%. Compared with LC-MS/MS, this assay is more convenient since the material can be prepared flexibly and the method can be applied on-site.
Graphical abstractSchematic of the fabrication of a molecularly imprinted chitosan hydrogel doped with CQDs for selective fluorometric determination of PFOS. a. The photo of chitosan hydrogel. b, c, d, e represents the hydrogel observed under UV lamp. b’, c’, d’, e’ represents the inner structure of hydrogel bead.
A novel Cu(II) ion-imprinted complex adsorbent [Cu(II)-IIP] from alginate and chitosan was prepared by a three-step process of beading–combining–crosslinking with Cu²⁺ as the template ion. The Cu(II)-IIP showed higher capacity and selectivity for Cu(II) than the non-imprinted polymer. The theoretical maximum adsorption capacity of Cu(II)-IIP reached 83.33 mg/g, and the separation factor (α) for Cu(II) versus Zn(II) was 2.28. The adsorption of Cu²⁺ onto the Cu(II)-IIP was perfectly described by the Langmuir isotherm model. The adsorption kinetics agreed with the pseudo-first-order model in the first 8 h and more fitted pseudo-second-order model after then. Weber–Morris model confirmed that the adsorption rate would be controlled dominantly by the intraparticle diffusion and the inner surface binding. Moreover, the Cu(II)-IIP complex adsorbent exhibited good regeneration, and the adsorption capacity was stable within the first three adsorption–desorption cycles without significant reduction.
Chitosan is obtained from alkaline deacetylation of chitin, and acetamide groups are transformed into primary amino groups during the deacetylation. The diverse biological activities of chitosan and its derivatives are extensively studied that allows to widening the application fields in various sectors especially in biomedical science. The biological properties of chitosan are strongly depending on the solubility in water and other solvents. Deacetylation degree (DDA) and molecular weight (MW) are the most decisive parameters on the bioactivities since the primary amino groups are the key functional groups of chitosan where permits to interact with other molecules. Higher DDA and lower MW of chitosan and chitosan derivatives demonstrated higher antimicrobial, antioxidant, and anticancer capacities. Therefore, the chitosan oligosaccharides (COS) with a low polymerization degree are receiving a great attention in medical and pharmaceutical applications as they have higher water solubility and lower viscosity than chitosan. In this review articles, the antimicrobial, antioxidant, anticancer, anti-inflammatory activities of chitosan and its derivatives are highlighted. The influences of physicochemical parameters of chitosan like DDA and MW on bioactivities are also described.
Magnetic molecularly imprinted polymers (MMIPs) have superior advantages in sample pretreatment because of their high selectivity for target analytes and the fast and easy isolation from samples. To meet the demand of both good magnetic property and good extraction performance, MMIPs with various structures, from traditional core–shell structures to novel composite structures with a larger specific surface area and more accessible binding sites, are fabricated by different preparation technologies. Moreover, as the molecularly imprinted polymer (MIP) layers determine the affinity, selectivity, and saturated adsorption amount of MMIPs, the development and innovation of the MIP layer are attracting attention and are reviewed here. Many studies that used MMIPs as sorbents in dispersive solid-phase extraction of complex samples, including environmental, food, and biofluid samples, are summarized.
Chitosan has been used as a functional monomer in the synthesis of molecularly imprinted polymers (MIP) for monosodium glutamate (MSG). MIP is made from a mixture of 5 g chitosan, 50 mg glutaraldehyde and 2 g MSG, MIP is formed as flakes and beads. MIPs are identified by the FTIR spectrum, SEM image and their adsorption capabilities. MIP flakes and beads have no structural differences if they are based on FTIR or SEM spectra, but MIP adsorption capacity of beads higher than flakes. Adsorption capacity of MIP flakes is 548 mg/g and MIP beads 627 mg/g.
In this work, a novel method was developed, using molecular imprinting, based on dopamine as a functional monomer, for isolation of S. aureus from complex (food) samples and fluorescence microscopy for detection. Conditions for preparation of molecularly imprinted polymers (MIPs), adsorption performance, adsorption kinetic, and selectivity of the polymeric layers were investigated. The various procedures were combined in a single extraction process, with the imprinted layer on the surface of the magnetic particles (magnetic MIPs). Subsequently, MIPs were used for extraction of S. aureus from milk or rice. Moreover, raw milk from cows with from mastitis was tested successfully. Using this novel MIP-based method, it was possible to detect bacteria in milk at 1x10³ CFU·ml⁻¹, which corresponds to the limit set in European Union legislation for microbial control of food.
An ion-imprinted sorbent (Ni-CDMO) derived from diacetylmonoxime (DMO)-chitosan Schiff base has been prepared by incorporating Ni(II) ion matching sites, which can selectively coordinate and recover Ni(II) ions from aquatic media. The chitosan was first modified by DMO to improve the targeted Ni(II) ion coordination and then the polymeric Ni-complex was treated with glyoxal to cross-link the polysaccharide chains and maintain the coordination sites rigid and inflexible after eluting the Ni(II) ions from the sorbent matrix. The maximum Ni(II) ion capacities of the Ni-CDMO and the control adsorbent C-CDMO were determined by performing the isotherm studies under different Ni(II) initial concentrations and treating the obtained experimental results using Langmuir and Freundlich models. The maximum capacity was around 135 mg/g, which is considered a high competing value. Furthermore, the competitive extraction of Ni(II) ions among various similar ions including Pb(II), Cu(II), Co(II), and Cd(II) was carried out using Ni-CDMO and C-CDMO and the results confirmed the distinct role of the utilized imprinting procedure in creating a considerable Ni(II) ion selectivity within the structure of the Ni-CDMO. Also, the regeneration and reusability experiments indicated the preservation of approximately 98% of the initial efficiency after the performance of five consecutive cycles.
Nickel with good corrosion resistance is usually used for electroplating. However, the human health and live environment will be in danger if the discharge of nickel wastewater exceeds certain levels. Nickel pollutants derive mainly from mining, smelting, electroplating, and other industries. Thus, it is very important to separate them from wastewater. One way is via surface imprinting. Here, chitosan, nickel nitrate and epichlorohydrin were used as substrate, template ion and cross-linking agent to synthesize a novel imprinted material for selective nickel adsorption. Adsorption kinetics study indicated that equilibrium was reached within 200 min and the adsorption behavior was in good agreement with a pseudo-second-order nonlinear model. The adsorption capacity approached 20.0 mg-g-1, and the selectivity to Ni2+ was 56.9, 55.2 and 49.2 in the presence of cobalt, calcium and manganese ions, respectively. In addition, the adsorption capacity remained at 96.1% after the polymer was reused five times. Overall, the imprinted polymer was a highly selective adsorbent for efficiently sequestering Ni and removing it from water.
In this work, a novel molecularly imprinted electrochemical sensor (MIES) has been fabricated based on electropolymerization of a molecularly imprinted polymer (MIP) onto a glassy carbon electrode (GCE) modified with gold-palladium alloy nanoparticles (AuPd NPs)/polydopamine film (PDA)/multiwalled carbon nanotubes-chitosan-ionic liquid (MWCNTs-CS-IL) for voltammetric and impedimetric determination of cholestanol (CHO). Modifications applied to the bare GCE formed an excellent biocompatible composite film which was able to selectively detect CHO molecules. Modifications applied to the bare GCE were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (SEM). Under optimal experimental conditions, the sensor was able to detect CHO in the range of 0.1-60 pM amd 1-50 pM by EIS and DPV, respectively. Moreover, the sensor showed high sensitivity, selectivity, repeatability, reproducibility, low interference and good stability towards CHO determination. Our records confirmed that the sensor was successfully able to the analysis real samples for determination of CHO.
In the current study, a green method was used for the fabrication of dual-template chitosan-based magnetic water-compatible molecularly imprinted biopolymer in water without using organic and toxic reagents and then, its application as a sorbent for the simultaneous pre-concentration and determination of valsartan (VAL) and losartan (LOS) from urine samples followed by HPLC-UV.
Chitosan was used as a multi-functional monomer due to its unique properties in terms of non-toxic, cost-effectiveness, readily available, biocompatible, biodegradable and easy to polymerize in mild condition. The proposed sorbent represents the exceptional properties in terms of green synthesis, high magnetic strength, bio-compatibility, high selectivity, fast equilibrium adsorption as well as high adsorption capacity. In the optimized conditions, the developed MMIP-DMSPE-HPLC/UV method showed a wide linear range of 5.0 − 1500.0 μg L⁻¹ for VAL and 8.0 − 1500 μg L⁻¹ for LOS and low LODs of 1.4 and 2.3 μg L⁻¹ for VAL and LOS, respectively with RSD% values less than 5.0, (n = 5). The obtained recoveries were 95.6-100.2% for VAL and 92.0-98.1% for LOS which showed the applicability of green, water-compatible and bio-compatibility of the proposed method for neat and selective extraction of VAL and LOS from complicated urine samples.
In this work, an optical sensor based on zinc oxide quantum dots (ZnO-QDs) was used to determine the chlorogenic acid (CGA). First, ZnO-QDs were prepared using a sol-gel method. Next, a thin film of silica was formed on the surface of ZnO-QDs using a reverse microemulsion technique. To prepare the molecularly imprinted polymer (MIP), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) were employed as a functional monomer and a cross-linker, respectively. Finally, the ZnO-QDsMIP composite was used to measure CGA. Different variables, affecting the optical signal of the sensor, were optimized. Under the optimal conditions, the linear dynamic range of the optical sensor was from 0.2 to
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CGA with a detection limit as
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. The effect of several potentially interfering species was investigated, and the results confirmed an excellent selectivity of the sensor for the measurement of CGA. Using this sensor to measure CGA in human plasma samples showed that the sensor is also capable of measuring CGA in complex matrix samples.
The toxicological and environmental damage caused by glyphosate [N-(phosphonomethyl) glycine] (GLY) has been well documented, however, limited efforts have been made to detect it in the environment. In response to that, we report the development of an extremely sensitive electrochemical sensor for GLY detection in water. This novel concept of glyphosate sensor is based on molecularly imprinted polymer (MIPs) made of chitosan (CS) biopolymer electrochemically deposited onto a gold microelectrode. Electrochemical Impedance Spectroscopy (EIS) was used for the label free detection of GLY in a linear range from 0.31 pg/ml to 50 ng/ml with a low detection limit of 0.001 pg/ml (S/N = 3). Moreover, the success of the MIPs layer affinity to GLY was confirmed through detection of GLY with non-imprinted CS (NIPs); a good imprinting factor of 14.5 was obtained. The selectivity of the MIPs was verified with the detection of different pesticides as interferences. Very high selectivity factors (SF) were obtained: 7.9 for glyfosinate, 43.5 for chlorpyrifos and 14.5 for phosmet.
Phenolic compounds such as catechol are present in a wide variety of foods and beverages; they are of great importance due to their antioxidant properties. Their consumption protects against the development of certain diseases such as cancer and cardiovascular diseases. A MIP chitosan (CS) film has been electrodeposited on a boron doped diamond (BDD) electrode, by chronoamperommetry in the presence of catechol, followed by elution with 0.1 M KCl. The morphology of the MIP and non-MIP (NIP) film has been studied by AFM. The electrochemical response of the sensor analyzed by cyclic voltammetry (CV) indicates that the sensor shows excellent reproducibility (RSD = 4.1%) and repeatability (RSD = 7.0%) for catechol detection in the range of 0 to 80 μM, with a detection limit of 6.9 × 10-7 M and high selectivity to catechol recognition versus different phenolic compounds. The results obtained in a red wine show that it can detect catechol in a complex matrix.
Rapid and accurate detection of proteins in biological fluids is increasingly required in the biomedical environment. Actually, it is performed with conventional techniques, which are generally run by robotized platforms at centralized laboratories. In this work, molecular dynamics calculations and an experimental procedure were conducted to set up electrochemical sensors based on polypyrrol (PPy) molecular imprinted polymers (MIP) for proteins detection. Here, prostate-specific antigen (PSA) was selected as a template model. Computational calculations indicate that for any PPy conformation and any amino-acid location in the protein, PSA molecules remain strongly inserted in the PPy polymer without biological alterations. One from possible orientations, appeared to be most probable as it presents the lowest absorption energy (-363 kcal mol-1) and largest contact area (4034.1 Å2). The device was then elaborated by in situ electropolymerization of PPy films. MIP's thickness and extraction duration were optimized by chronoamperometry. Square wave voltammetry technique was investigated for PSA detection in standard solution in the concentration range of 3x10 -8 ng.ml-1- 300 ng ml-1. According to the Hill equation, the equilibrium dissociation constant Kdbetween PSA and its imprint was estimated at Kd = (1.02 ± 0.54) × 10-14 M, confirming the strong binding between the designed MIP and the protein as predicted by the computational study. PSA concentration values directly measured in 35 human serum samples were found closely correlated to those measured by the ELISA technique. The promising fast and low-cost sensor might be used successfully for proteins detection at low concentrations with high selectivity and reproducibility.
As a kind of mycotoxins, patulin has been a usual contamination in apple juice and causes a serious public health concern nowadays. Regarding this issue, a novel and effective adsorbent, Fe3O4@SiO2@[email protected], is designed to remove the patulin from apple juice. Firstly, the molecularly imprinted polymer (MIP) was prepared by surface imprinting technique. Meanwhile, addition of Fe3O4 makes the final prepared MIP adsorbent magnetic, which is beneficial for separating the adsorbent from the food matrix. Moreover, chitosan (CS) and SiO2 improve the biocompatibility, stability and dispersibility of the MIP adsorbent effectively. As for the adsorption performance, batches of experiments were conducted on the proposed adsorbent. Experimental results showed that the adsorption process followed pseudo-second-order kinetic and Freundlich isotherm model, and the physical multi-molecular layer endothermic adsorption happened during the whole adsorption process. Adsorption capacity of the proposed adsorbent is 7.11 mg/g maximumly, and over 90% of the total patulin in apple juice being removed after 24 h. Besides, the proposed adsorbent has distinguishing characteristics, including large specific surface area with BET reaching 279.6 m²/g, high cell viability of 79.77% and no negative effects on final quality parameters. The desirable adsorption performance and characteristics make Fe3O4@SiO2@[email protected] a promising adsorbent for removing the patulin from apple juice in the future.
A novel thermo-sensitive lead ion-imprinted polymers (IIPs) based on multi-walled carbon nanotubes(MWCNTs) was prepared by reverse suspension polymerization, using chitosan (CS), hydroxyethyl methacrylate and N-isopropylacrylamide as the polymeric monomers, Pb(II) as the template and glutaraldehyde as the crosslinking agent. The chemical structure, morphology and magnetic properties were characterized by Fourier transform infrared spectrometer(FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), thermogravimetry (TGA), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The adsorption properties of IIPs were investigated by ultraviolet spectrophotometr (UV–vis) and atomic absorption spectrophotometry (AAS). The results showed that IIPs had obvious temperature sensitivity, and the adsorption capacity and the adsorption equilibrium time of imprinted polymers could be controlled by changing the temperature. The maximum adsorption capacity of IIPs for Pb²⁺ reached 83.20 mg/g at 35 ℃. The adsorption process was more in accord with the pseudo second-order kinetic and the Langmuir isotherm adsorption model. The selectivity coefficients of Pb²⁺/Cu²⁺, Pb²⁺/Cd²⁺, Pb²⁺/Zn²⁺ and Pb²⁺/Ni²⁺ were 15.66, 59.50, 24.79 and 20.52, respectively, indicating that IIPs had excellent selective adsorption for Pb²⁺. In addition, IIPs was recycled 6 times, and the adsorption capacity was not obviously reduced. The electrochemical properties of ion-imprinted carbon paste electrodes (CPE/IIPs) were characterized by cyclic voltammetry (CV), and CPE/IIPs exhibited excellent electrochemical performance.
A novel Cu–Co-zeolite imidazole framework (Cu–Co-ZIF)-derived CuCo2O4@carbon nanocomposites supported on three-dimensional porous carbon (3D-KSC) were prepared to develop molecularly imprinted electrochemical sensors for sensing dopamine (DA). Firstly, polyhedral Cu–Co-ZIF was synthesized at room temperature and uniformly arrayed on 3D-KSC, and then the CuCo2O4@carbon nanostructure was obtained by high-temperature carbonization under nitrogen atmosphere. Finally, the molecularly imprinted polymer (MIPs) DA-imprinted chitosan was covered by potentiostatic electrodeposition to obtain the MIPs/CuCo2O4@carbon/3D-KSC integrated electrode. The results showed 15 μm-sized polyhedral Cu–Co-ZIF crystals were transformed into smaller irregular porous CuCo2O4@carbon nanocomposites with rough surface by calcination. Here, the produced 5 nm-sized CuCo2O4 crystals were uniformly embedded into the N-doped porous carbon frameworks. Various experimental conditions including the amount of Cu–Co-ZIF grew on 3D-KSC, calcination temperature, electrodepositing time of MIPs, the eluted time of template molecule and the pH of electrolyte were explored. The as-prepared MIPs/CuCo2O4@carbon/3D-KSC integrated electrode exhibited excellent anti-interference ability and good stability. The sensitivity for DA detection was 720.8 μA mM⁻¹cm⁻², the detection range was 0.51 μM–1.95 mM, and the detection limit was 0.16 μM.
An S‐mandelic acid (MA) imprinted chitosan resin (SMIC) was synthesized by cross‐linking chitosan with glutaraldehyde in 2% acetic acid solution. SMIC was used to enantioselectively separate racemic MA in aqueous medium. When keeping the pH of sample solution (100 mM Tris‐H3PO4) at 3.5 and adsorption time at 40 min, the enantiomer excess (ee) of MA in supernatant was 78.8%. The adsorption capacities of SMIC for S‐ and R‐MA were determined to be 29.5 and 2.03 mg g−1, respectively. While the adsorption capacities of non‐imprinted cross‐linked chitosan for S‐ and R‐MA were 2.10 and 2.08 mg g−1, respectively. The result suggests that the imprinted caves in SMIC are highly matched with S‐MA molecule in space structure and spatial arrangement of action sites. Interestingly, the ee value of MA in supernatant after adsorption of racemic MA by R‐MA imprinted cross‐linked chitosan was 25.4%. The higher ee value by SMIC suggests that the chiral carbons in chitosan and the imprinted caves in SMIC combine to play roles for the enantioselectivity of SMIC toward S‐MA. Furthermore, the excellent enantioselectivity of SMIC toward S‐MA demonstrates that using chiral chitosan as functional monomer to prepare molecularly imprinted polymers has great potential in enantioseparation of chiral pharmaceuticals. This article is protected by copyright. All rights reserved
Pickering emulsion polymerization has been employed for the Ultrasonic assisted-micro solid phase extraction (UA-µSPE) of ultra trace arsenic species by a new magnetic ion imprinted polymer (MIIP) prior to hydride generation atomic absorption spectrometry. 2-acetyl benzofuran thiosemicarbazone (2-ABT) as a new chelating agent and core- shell hydrophobic magnetic nanoparticles was synthesized and the polymerization was carried out at the presence of arsenic - ligand complex, crosslinker, monomer, initiator, stabilizing agent and water-oil emulsion magnetic carrier. In second step, the nanoparticles and polymers were characterized. The analytical parameters such as pH, amount of polymer and ultrasonic time were selected and optimozed by Plackett-Burman and Box-Behnken designs respectively. Linear dynamic range, detection limit and relative standard deviation were 0.01-85.000 µg·L-l, 0.003 µg·L-l, and 3.21%, respectively. The proposed preconcentration procedure was successfully applied to the determination of arsenic ion in a wide range of food samples with different and complex matrixes.
A tryptophan (Trp) molecularly imprinted electrochemical sensor was fabricated by drop-coating an imprinted chitosan film on the surface of a glassy carbon electrode modified with multi-walled carbon nanotubes (MIP-MWCNTs/GCE). The surface morphology and electrochemical properties of the MIP-MWCNTs/GCE were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV), respectively. The formation of hydrogen bonds between the functional polymer and the template molecule was confirmed by infrared spectroscopy. The electrochemical performance of the MIP-MWCNTs/GCE with Trp showed that the signal of the oxidation current of Trp obtained with MIP-MWCNTs/GCE was significantly enhanced relative to that of the uncovered GCE, indicating that the modified electrode can accelerate electron transfer and has strong selectivity for Trp. The experimental conditions were optimized in parallel, and under the optimal conditions, the MIP-MWCNTs/GCE showed a good linear relationship between the Trp oxidation peak current and Trp concentrations in the ranges of 2.0 nM–0.2 μM, 0.2 μM–10 μM and 10 μM–100 μM The limit of detection (LOD) was 1.0 nM (S/N = 3), and the modified electrode had good reproducibility and stability. Finally, the MIP-MWCNTs/GCE was successfully applied to the determination of Trp in the human serum samples.
A novel green magnetic molecularly imprinted solid phase extraction (MMI-SPE) for separation of memantine (MEM) from complicated matrices was proposed. The nanomaterial was synthesized via crosslinking of chitosan (CHIT) with [3-(2, 3-epoxypropoxy)-propyl] trimethoxysilane (EPPTMS) in presence of MEM as a template. The nanocomposites, in all steps, were characterized by SEM, FTIR and PXRD techniques. The adsorbed drug was removed from magnetic molecular imprinted polymer (MMIP) cavity by ethanol: acetic acid (8:2, v/v) and then, coupled with sodium 1, 2-naphthoquinone-4-sulphonate (NQS) in iodine/alkaline medium to yield highly fluorescent product, after reduction with potassium borohydride (KBH4). Variables affecting extraction of MEM from imprinted sites and its fluorometric analysis were studied. The linearity was achieved over concentration range of 1.84-95.0 ng mL-1 with LOD of 0.6 ng mL-1. The method was successfully applied for determination of MEM in its pharmaceutical tablets and human serum with recoveries of 100.8 ± 3.0, 97.6 ± 2.9, respectively.
The purpose work is devoted to design of a simple, one-pot and green approach for the synthesis of molecularly imprinted polymer to construct a selective sorbent for pipette-tip solid phase extraction of Rhodamine B from chili powder samples and its subsequence separation and quantification by high performance liquid chromatography-ultraviolet/visible detection. The prepared molecularly imprinted polymer was synthesized using chitosan as versatile natural multi-functional bio-monomer and Rhodamine B as template in aqueous media. The effects of influential parameters (sorbent dosage, flow rate and eluent solvent volume) and their influences on Rhodamine B extraction recovery were examined and optimized by central composite design based response surface methodology as a powerful multivariate optimization tool. Under the optimized conditions, the linear range and limit of detection and quantification of proposed method were achieved to be 0.005-15 mg kg-1, 0.0015 mg kg-1 and 0.00488 mg kg-1, respectively, with satisfactory recoveries (>85.0%) and excellent repeatability (relative standard deviation < 6.1%). The easy synthesis conditions as well as satisfactory figures of merit are good indication of applicability of suggested method for extraction and determination of Rhodamine B from chili powder samples in terms of simplicity, cost effectiveness, selectivity and accurate analysis.
An ion imprinting polymer (IIP) electrochemical sensors based on chitosan-graphene oxide composites polymer modified glassy carbon electrode (CS/GO-IIP) was developed for the highly sensitive and selective detection of Cu (II) by the dip coating method. The Cu (II) ion-imprinted polymers were synthesized by chemically cross-linking with epichlorohydrin after the CS/GO/Cu (II) composite dropped on the glassy carbon electrode surface. The introduction of GO can improve the electrical conductivity of the electrode and amplify the electrochemical signal. The sensor was characterized by FT-IR, EDS, SEM, AFM, Raman spectroscopy and electrochemical measurements. Under the optimized conditions, a linear dependence was observed from 0.5 to 100 μmol/L with a detection limit of 0.15 μmol/L. The detection of Cu (II) was hardly interfered by the traditional metal cations. The CS/GO-IIP sensor showed excellent reproducibility via repetitive differential pulse anodic stripping voltammetry and the RSD was 3.3%. More importantly, the performance of CS/GO-IIP sensor was verified in tap and river water samples and has an acceptable recovery rates.
Via heat of hydration, Pb(II)imprinted membrane composite adsorbent was prepared using glutaric acid as modifier, Pb(II)as imprinted ion, chitosan-blended polyvinyl alcoho as support material, and glutaraldehyde as cross-linking agent. The structure and morphology of the adsorbent were characterized with FTIR, XRD, EDS, and SEM. In the presence of Cu(Ⅱ), Ni(Ⅱ), Zn(Ⅱ), etc., the adsorption selectivity toward Pb(II)of the adsorbent in aqueous solution was studied, showing that glutaric acid modified Pb(II)imprinted chitosan-based composite membrane had a good adsorption selectivity toward Pb ²⁺ in aqueous solution. The adsorption process of the membrane was under chemical reaction and was in line with the McKay quasi-secondary reaction kinetics model.
A versatile, robust and efficient differential potential ratiometric sensing platform was developed for enantioselective recognition of dual chiral targets based on a composite membrane of molecularly imprinted polymers (MIPs) and reduced graphene oxide (rGO) modified glassy carbon electrode (GCE). The functional chitosan-based MIPs and rGO were compatibly immobilized on the GCE with high selectivity and efficient signal amplification. Moreover, via the systematic optimization of series conditions, a distinct potential difference (PD), reaching 135 mV, was obtained between the R-/S-prop based on the MIPs/rGO/GCE. In a controllable concentration range from 50 μM to 1000 μM, different ratios of R-/S-prop were linearly related to the peak potentials (Eps) in the racemic mixture. Using this low-cost reversible electrochemical platform, both Prop enantiomers were simultaneously identified with high repeatability and time-based stability. This novel semi-quantitative electrochemical sensing platform was established to rapidly quantify the ratio of S-/R-prop by Ep for the chiral drug recognition with great potential for practical applications in fields of pharmacological detection and clinical analysis.
Solid-phase extraction of polycyclic aromatic sulfur heterocycles (PASHs) and their rapid determination in oil fuel without tedious sample pretreatment are of high interest. We propose porous and optically transparent hydrogels prepared from the covalently crosslinked chitosan (CS) as the basis for a sensor system for the rapid and robust monitoring of PASHs. We efficiently combined the ability of the crosslinked CS to sorb PASHs, the capacity of microcavities in a molecularly imprinted polymer to selectively recognize and trap analytes, and the optical transparency of CS materials for selective sorption and solid-phase fluorometric determination of dibenzothiophenes. For the screening of PASHs in organic nonpolar media, ortho-phtalic dialdehyde appeared to be the most appropriate crosslinker. Synthetic and analytical procedures performed in microplate mode allowed obtaining CS hydrogels with suitable reproducible properties and their further time- and labor-efficient applying in analysis (particularly, as little as 2 μM dibenzothiophene oxide can be determined).
Molecular imprinting enables the fabrication of versatile functional polymers with pre-designed molecular target selectivity, inherent robustness, reusability, and reproducible production. Using advanced synthesis strategies, molecularly imprinted polymers even offer potential for virus recognition, which is of substantial interest as viral analysis and selective detection is a field of continuous development given increasing occurrence of viral variants and drug resistance. In this review, we discuss the most relevant virus imprinting strategies along with critical barriers for synthesizing virus-imprinted materials. Furthermore, selected applications are highlighted.
A well-defined molecularly imprinted polymer (Fe3O4@[email protected]) was synthesized via reversible addition-fragmentation chain transfer polymerization for magnetic solid-phase extraction coupled with high-performance liquid chromatography-diode array detector to detect carbamazepine (CBZ) in biological samples. The composition of Fe3O4@[email protected] was selected by a two-step screening method. 4-vinyl pyridine, divinylbenzene and dimethylformamide were chosen as the functional monomer, cross-linker and porogen, respectively. The imprinted layer was coated on the surface of the chain transfer agent-modified magnetic chitosan nanoparticles. The prepared Fe3O4@[email protected] was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller measurement and vibrating sample magnetometer. The results indicated that Fe3O4@[email protected] had a large surface area (265.8 m²/g), high saturation magnetization (19.88 emu/g) and uniform structure. Besides, the binding property of the Fe3O4@[email protected] was studied in detail. The Fe3O4@[email protected] showed high imprinting factor (IF = 4.83) and desirable adsorption capacity (323.10 μmol/g) to CBZ. Under the optimum conditions, the developed method exhibited excellent linearity (R²>0.999) in the range of 0.01–0.5 mg/L and 1.0–30.0 mg/L, and the limits of detection were 1.0 μg/L and 9.6 μg/L for the urine and serum samples, respectively. Good recoveries (88.22%–101.18%) were obtained with relative standard deviations less than 4.83%. This work provided a practical approach for the selective extraction and detection of CBZ in real samples.
Green ion imprinted polymers (IIPs) were prepared in aqueous phase via the synergy of three functional monomers of low-cost eco-friendly gelatin (G), 8-hydroxyquinoline (HQ) and chitosan (C), namely G-HQ-C IIPs, and were applied as an effective and recyclable adsorbent to remove Cu(II) from aqueous solution. The as-prepared G-HQ-C IIPs were systematically characterized, and several major factors affecting adsorption capacity including solution pH, temperature and contact time were investigated in detail. The adsorption of Cu(II) on G-HQ-C IIPs followed the pseudo-second-order kinetic and Langmuir isotherm models, and the adsorption capacity increased with temperature increase. Moreover, the maximum adsorption capacities of G-HQ-C IIPs toward Cu(II) reached up to 111.81 mg/g at room temperature, much higher than those of most of the reported adsorbents for Cu(II). The G-HQ-C IIPs displayed excellent selectivity against seven common divalent ions with selectivity coefficients above 18.71, as well as high anti-interference ability. Additionally, a good reusability was demonstrated without significant loss in adsorption capacity after at least ten cycles. The IIPs were applied to environmental water samples for selective removal of Cu(II) with satisfactory results. By replacing Cu(II) template by Cd(II), Hg(II) and Pb(II), respectively, the obtained three kinds of IIPs based on G-HQ-C presented convincing imprinting properties, and therefore the work could provide a simple and general imprinting strategy toward various concerned heavy metal ions through multi-point interactions from multiple functional monomers.
In this paper, we report for the first time a novel, simple and fast method for the synthesis of magnetic molecularly imprinted polymers (Mag-MIPs) based on high-energy ultrasound probe. Sulfamethoxazole (SMX) was used as template molecule, methacrylic acid as functionnal monomer, ethylene glycole dimethacrylate as crosslinking agent and magnetic nanoparticles (NPs) as the supporting core. The effects of time (5, 7.5 and 10 minutes) and the applied amplitude (20, 30, 40, 50 and 60%) using the ultrasound probe for the synthesis of Mag-MIPs were studied and optimized. By applying the proposed synthesis method, the US-magMIPs synthesis time was satisfactorily reduced from several hours to a few minutes (7.5 min) in a simple way. For comparison purposes, the Mag-MIP and the non imprinted polymer (magNIP) were also synthesized employing an ultrasound bath assisted approach (2 h, 65 °C).
Magnetic NPs and US-magMIPs synthesized by both ways were investigated by means of several characterization techniques such as Fourrier Transform Infrared (FT-IR) spectroscopy, Scanning/Transmission electron microscopy (SEM and STEM modes), X-Ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM) and Dynamic Light Scattering (DLS). The results obtained confirms clearly the formation of magnetic NPs and their successful decoration by the imprinted polymer in both synthesis ways.
The sulfonamide binding efficiency of US-magMIPs synthesized by the untrasound probe and ultrasound bath were investigated according to the adsorption isotherm. The obtained results showed that the US-magMIP synthesized with the probe has more binding capacity compared to the one synthesized with US bath. The adsorption time was studied and both synthesized US-magMIPs reached the maximum adsorption capacity toward SMX after 1 hour and the US-magMIP probe tends to have more easiness to bind SMX in less time. The selectivity studies of the synthesized US-magMIPs based on probe and bath showed a high affinity for SMX compared to its structural analogues such as sulfadiazine, sulfamerazine and sulfacetamide.
An efficient surface Pb(Ⅱ) ion-imprinted polymer based on sandwich-like graphene oxide composite materials (GO-IIP) was synthesized and characterized for studying the morphology and adsorption properties. Effects of preparation and adsorption conditions including solvent type, molar ratio of functional monomer to crosslinking agent, initiator dosage, pH, adsorbent dosage, contact time, ions concentration on the Pb(Ⅱ) removal were studied. Adsorption equilibrium was reached within 30 min and the adsorption process followed pseudo-second-order kinetic and Langmuir adsorption isotherm models, indicating chemisorption was the rate-limiting step. The maximum adsorption capacity of Pb(Ⅱ) ion-imprinted polymer was as high as 40.02 mg g⁻¹ at 25 ℃ which was much higher than that of the non-imprinted polymer (20.45 mg g⁻¹). The selectivity coefficient of Pb / Zn, Pb / Cd, Pb / Co, Pb / Ni and Pb / Ca were 20.12, 14.26, 31.67, 25.65 and 81.29, respectively, further confirming the satisfactory selectivity of GO-IIP. In addition, the prepared adsorbent could be reused 5 times without significant reduction of the adsorption capacity. Furthermore, an XPS spectra analysis was successfully applied to exploring the possible adsorption mechanism between Pb(Ⅱ) and GO-IIP, indicating that nitrogen atom in the amide bond of the functional monomer was the main coordination atom.
ABSTRAC T
Polymer particles imprinted for the protein trypsin (MIPs) were synthesized via miniemulsion polymerization.
The in fl uence of the nature of the cross-linker and the incubation time on the characteristics of the polymer particles was investigated. Optimized results concerning binding capacity and selectivity were obtained for MIPs utilizing methacrylic acid and ethylene glycol dimethacrylate for generating MIP particles with a diameter of 200 nm. It was found that thus obtained materials follow pseudo-second order sorption kinetics when rebinding the template. These MIP particles were then used as molecular recognition element for biomimetic piezoelectric sensors directly assaying trypsin. The obtained calibration functions corroborated a linear response in a con-centration range of 0.125–2 μ gmL−1 with a limit of detection at 0.07μ gmL-1 . Finally, the developed sensor was tested for the detection of trypsin in pharmaceutical formulations.
Molecular imprinting is the process of template-induced formation of specific recognition sites in a polymer. Synthetic receptors prepared using molecular imprinting possess a unique combination of properties such as robustness, high affinity, specificity, and low-cost production, which makes them attractive alternatives to natural receptors. Improvements in polymer science and nanotechnology have contributed to enhanced performance of molecularly imprinted polymer (MIP) sensors. Encouragingly, recent years have seen an increase in high-quality publications describing MIP sensors for the determination of biomolecules, drugs of abuse, and explosives, driving toward applications of this technology in medical and forensic diagnostics. This review aims to provide a focused overview of the latest achievements made in MIP-based sensor technology, with emphasis on research toward real-life applications.
The present work demonstrates functionalized chitosan as an ecofriendly substitute to the conventional costly substrates and monomers for simultaneous surface imprinting of salicylic acid (SA) and cadmium (Cd). Dual surface imprinted acrylamide functionalized chitosan based polymer (AGDMIP), with higher numbers of imprinted sites for SA and Cd was synthesized using acrylamide grafted chitosan, epichlorohydrin as crosslinker, Cd as template and 4 hydroxy benzoic acid (4HBA) as mimic template (supported by computational modeling). FTIR, SEM, XRD, BET surface area and TEM analysis confirmed successful preparation, mesoporous nature and surface imprinting of AGDMIP. The adsorption data could be fitted into Langmuir isotherm model with the maximum adsorption capacity of 45.77 mg g⁻¹ (SA) and 53.42 mg g⁻¹ (Cd). Temkin and Intraparticle diffusion models confirmed the chemical nature and presence of imprint sites within AGDMIP respectively. AGDMIP could be reused for six cycles and exhibited good removal efficiency in real samples.
In this work, a novel molecularly imprinted electrochemical sensor (MIECS) based on a glassy carbon electrode (GCE) modified with carbon dots (CDs) and chitosan (CS) for the determination of glucose was proposed for the first time. The use of the environmental-friendly CDs and CS as electrode modifications improved the active area and electron-transport ability substantially, while 3-aminobenzeneboronic acid was used as a functional monomer and glucose as template for the fabrication of molecularly imprinted polymer (MIP) film to detect glucose via differential pulse voltammetry. Transmission electron microscope, Fourier transform infrared spectroscopy, energy dispersive x-ray spectrometry, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were applied to characterize the fabricated sensor. Experimental conditions such as molar ratio of functional monomer to template, volume ratio of CDs to CS, incubation time and elution time were optimized. By using glucose as a model analyte, the MIECS had two assay ranges of 0.5-40 μM and 50-600 μM, and fairly low limit of detection (LOD) of 0.09 μM (S/N = 3) under the optimized conditions. The MIECS also exhibited excellent selectivity, good reproducibility, and stability. The proposed sensor was successfully applied to a preliminary test for glucose analysis in real human blood serum samples.
A sensitive and selective electrochemical sensor based on ion-imprinted chitosan-graphene nanocomposites (IIP-S) has been developed for the determination of Cr(VI). The ion-imprinted polymers were constructed by one-step electrodeposition. The morphology and structure of IIP-S were characterized by SEM, TEM, XRD, FTIR and EDS, respectively. Meanwhile, the electrochemical behavior of IIP-S was investigated using CV, EIS and DPV. The linear range of IIP-S was from 1.0 × 10⁻⁹ to 1.0 × 10⁻⁵ mol/L, with the low detection limit of 6.4 × 10⁻¹⁰ mol/L (S/N = 3). The sensor exhibited high selectivity for the determination of Cr(VI) in the presence of Zn(II), Co(II), Cu(II), Ni(II), Mn(II), MnO⁴⁻, C2O4²⁻, S2O6²⁻ and MoO4²⁻ ions. The IIP-S also provided excellent stability and good repeatability that the sensitivity remained 85% after 9 cycles of rebinding-removal, while the sensitivity retained 87% of its initial response storing at 4 °C for 17 days. Moreover, it was successfully applied to the detection of Cr(VI) ions in tap water and river water.
Spent Nickel cadmium (Ni-Cd) batteries are classified as hazardous waste due to the presence of toxic cadmium (Cd). Sustainable solution to this problem can be adoption of resource recovery methods for the reuse of Cd. This has been attempted in the present work using the biopolymer chitosan having inherent affinity for metals. Stability of chitosan in acidic medium was improved by grafting it with a suitable grafting agent and crosslinking. Further, it was used for the synthesis of acrylamide grafted chitosan based Cd ion imprinted polymer (CdIIP) using Cd as template and epichlorohydrin (EPI) as crosslinker for the selective recovery of Cd. Density Functional Theory (DFT) confirmed acrylamide as the best grafting agent with ΔG of −17.98 Kcal/mol for the acrylamide grafted chitosan. FTIR confirmed the grafting of acrylamide on chitosan as well as successful synthesis of CdIIP. EPI proved to be a better crosslinking agent as compared to glutaraldehyde (GLA) for CdIIP as confirmed by EDS. Adsorption of Cd on the CdIIP was influenced by pH, time, initial Cd concentration and CdIIP dose. The kinetic data fitted well to pseudo-second-order equation than first order with R² equals to 0.997. The monolayer adsorption capacity for Cd (167 mg/g) calculated using Langmuir isotherm model was in close approximation to the experimental adsorption capacity of 152 ± 3 mg/g. The thermodynamic data confirmed exothermic and spontaneous nature of adsorption. 84.3% of Cd could be recovered by CdIIP from the acidic leachate of the Ni-Cd battery waste. CdIIP could be effectively reused for five cycles.
Two types of molecular-imprinted polymers-based magnetic chitosan with facile deep eutectic solvent-functional monomers (Fe3O4-CTS@DES-MIPs) were synthesized and applied as adsorbents in magnetic solid-phase extraction (MSPE) for the selective recognition and separation of (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin gallate in black tea. The obtained Fe3O4-CTS@DES-MIPs were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The selective recognition ability was examined by adsorption experiments. The actual amounts of (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin gallate extracted from black tea using Fe3O4-CTS@DES-MIPs by the MSPE method were 13.10 mg g⁻¹, 6.32 mg g⁻¹, and 8.76 mg g⁻¹, respectively. In addition, the magnetic Fe3O4-CTS@DES-MIPs showed outstanding recognition and selectivity. Therefore, it can be used to separate bioactive compounds from black tea. The new-type of DES adopted as the functional monomer in this paper provides a new perspective for the recognition and separation of bioactive compounds.