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Basic structure of PANi and different redox forms of PANi with its doped states. Abbreviation: PANi, polyaniline.
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Biosensors are the subject of an immensely growing field of research owing to their broad range of applications in medicines, pharmacy, environmental monitoring, food and process control, defense and security, and principally in diagnostics. Diverse materials have been investigated for the advancement of biosensors in terms of their miniaturization...
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... unprotonated and protonated forms of PANI are known as base and salt, respectively. 10 Figure 2 shows different base and salt forms of PANI in its three redox forms. Conclusively, the conductivity of PANI can be tuned by using different doping agents, varying the extent of doping, and also by controlling the chain length and morphology including the dimensions and porosity of PANI. ...
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... The various nanostructures of polyanilines have been reported as electrochemical electrode materials, including nanoparticles, nanosheets, and nanotubes [40,41]. However, the nanofiber nanostructure has the advantage of being a porous structure that provides more active sites for redox reactions [42]. ...
The measurement of glucose concentration is a fundamental daily care for diabetes patients, and therefore, its detection with accuracy is of prime importance in the field of health care. In this study, the fabrication of an electrochemical sensor for glucose sensing was successfully designed. The electrode material was fabricated using polyaniline and systematically characterized using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and UV-visible spectroscopy. The polyaniline nanofiber-modified electrode showed excellent detection ability for glucose with a linear range of 10 μM to 1 mM and a detection limit of 10.6 μM. The stability of the same electrode was tested for 7 days. The electrode shows high sensitivity for glucose detection in the presence of interferences. The polyaniline-modified electrode does not affect the presence of interferences and has a low detection limit. It is also cost-effective and does not require complex sample preparation steps. This makes it a potential tool for glucose detection in pharmacy and medical diagnostics.
... 4,5 EB is converted to conducting emeraldine salt (ES) by acid doping, which leads to effective corrosion control in acidic solutions. 18,19 PANI's protective coating for metallic surfaces provides high corrosion resistance 14 by forming adjacent layers of passive metallic oxide such as Fe 3 O 4 , α-Fe 2 O 3 , and γ-Fe 2 O 3 2,6,20,21 or forming nitrides 22 and by promoting the passivation of the coated substrates. The metal surface is shielded from further corrosion by these thick oxide layers that serve as physical barrier protection. ...
This study explores conducting polymers with side chains containing long, branched alkyl groups as candidates for corrosion suppression coatings. These polymers, containing carbazole, phenothiazine, and phenoxazine cores, may be considered as analogues to polyaniline, which is often employed in corrosion control applications. The polymers are prepared from the corresponding dibrominated carbazole, phenothiazine, and phenoxazine mono-mers with 2,5-dimethyl-1,4-phenylenediamine by the Buchwald−Hartwig coupling reaction. The effectiveness of these coatings for corrosion suppression was tested by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The morphology of the coatings was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Corrosion testing of coated AISI 4130 steels in 3.5 wt % NaCl showed that the phenothiazine-and carbazole-containing polymers display excellent corrosion resistance. The protection efficiency (PE) of 95.9% for phenothiazine outperformed the other polymers, including polyaniline coating. SEM images indicate that the polymers are still uniformly coated with stable morphology after 24 h of exposure to corrosive media. These results suggest that phenothiazine-and carbazole-based PANI analogues may be candidates for protective organic coatings in transportation, aviation, marine, and oil and gas industrial applications.
... PANI is a polymer widely used in the design of biosensors thanks to its advantages of chemical and mechanical stability and its possession of dual-redox couple electrochemical behavior [77]. "Third-generation" biosensors are based on direct electron transfer from the enzyme to the working electrode mediated by the conducting polymer. ...
L-Dopa is an intermediate amino acid in the biosynthesis of endogenous catecholamines, such as dopamine. It is currently considered to be the optimal dopaminergic treatment for Parkinson’s disease, a neurodegenerative disorder affecting around 1% of the population. In an advanced stage of the disease, complications such as dyskinesia and psychosis are caused by fluctuations in plasma drug levels. Real-time monitoring of L-Dopa levels would be advantageous for properly adjusting drug dosing, thus improving therapeutic efficacy. Electrochemical methods have advantages such as easy-to-use instrumentation, fast response time, and high sensitivity, and are suitable for miniaturization, enabling the fabrication of implantable or wearable devices. This review reports on research papers of the past 20 years (2003–2023) dealing with enzyme-based biosensors for the electrochemical detection of L-Dopa in biological samples. Specifically, amperometric and voltammetric biosensors, whose output signal is a measurable current, are discussed. The approach adopted includes an initial study of the steps required to assemble the devices, i.e., electrode modification and enzyme immobilization. Then, all issues related to their analytical performance in terms of sensitivity, selectivity, and capability to analyze real samples are critically discussed. The paper aims to provide an assessment of recent developments while highlighting limitations such as poor selectivity and long-term stability, and the laborious and time-consuming fabrication protocol that needs to be addressed from the perspective of the integrated clinical management of Parkinson’s disease.
... Doping also reduces the energy gap between PA's valance band (VB) and conducting band (CB) and increases charge carrier density and electrical conductivity (Figure 1b) [5]. Shortly after their discovery, numerous other organic polymers half-oxidized, and the pernigraniline base (PB) (blue/violet) is the fully oxidized form [1,26,27]. The leucoemeraldine base form has only benzenoid rings, the emeraldine base form has both benzenoid and quinonoid rings, while the pernigraniline base form has only the quinoid rings [18]. Upon doping, the emeraldine base is converted to the emeraldine salt (ES) (green) and becomes conducting. ...
Polyaniline (PANI) is one of the oldest, yet most profound conducting polymer discovered. It’s ease of synthesis, high conductivity, and environmental stability in the doped state makes it very attractive for a variety of potential applications. However, its insolubility and lack of redox stability has hindered many commercial applications. Consequently, many researchers have sought to overcome PANI’s deficiencies in many ways including the development of PANI derivatives. This chapter will discuss the synthesis, properties, and applications of PANI derivatives. We will discuss three types of PANI derivatives—substitution on the benzene ring, substitution on the nitrogen atom, and fused ring cores. The properties of the PANI-derivatives will be compared to pristine PANI. Finally, we will emphasize the applications that arise from these derivatives and how they compare to PANI.
... For example, the surface functional group of the polymer is directly related to the electrochemical performance and sensitivity to free radicals [9,10]. Among the conductive polymers, polyaniline (PANI) is one of the well-known conductive polymers, particularly for promising potential in biotechnology applications, due to its high electrical conductivity, hydrophilic nature, low toxicity, chemical stability, low solubility, and biocompatibility [11,12]. Due to its physical suitability for biomaterial production both in vivo and in vitro applications, PANI has been widely investigated in technological applications of biosensors, neural probes, controlled drug delivery, and tissue engineering [3,13,14]. ...
... As a result of allowing surface modifications with functional groups, PANI becomes advantageous due to its two main tunable properties, conductivity and biocompatibility. H ? ion or/and cationic defects (polarons, bipolarons) modify the conductivity and redox behavior of PANI [12]. On the other hand, PANI has an acquired and improved biocompatibility features as an electrochemical immunosensors or drug delivery materials through surface modifications of functional groups such as -COOH, -OH, -SH, or -NH 2 [15,16]. ...
The study was based on surface functionalization of conductive PANI (polyaniline) polymer for drug delivery systems. Specifically, an electrochemical polymerization technique was performed for the synthesis of PANI layers on tin-doped indium oxide (In2O3:Sn or ITO)-coated PET (polyethylene terephthalate) substrates. Three main factors were studied: binding ability, drug-loading ability and drug-delivering ability. PANI layers, combined with active carbon (AC), were organized as biomaterials to carry the anticancer drug doxorubicin (DOX). Two different films, PANI and PANI with AC, were polymerized in the emeraldine salt form of PANI. A comparison of the two samples proved that AC molecules enabled DOX molecules to bind to the PANI surface, as observed by the UV–Vis absorption spectra of the films. DOX molecules were detected by UV–Vis spectra with an absorption peak at 547 nm. Findings from drug loading/release tests and in vitro cytotoxicity results confirm that these films can be used as drug delivery systems. This work underlines essential role of AC in the PANI layer for drug delivery.
... Due to their biodegradability, bio-based materials have been proposed to help in reducing the massive amounts of e-waste [4]. Moreover, if the electronic products are designed for human health solutions such as biochips for biosensing or as drug delivery systems, the biocompatibility of biobased materials is a major advantage [5,6]. Despite the interesting properties of bio-based materials, the research on their inclusion in electronics is limited to their use as inactive Figure 1. ...
Electronic waste (e-waste) is the fastest growing waste stream and its negative impact on the environment and human health is major because of the toxicity and non-biodegradability of its constituents. For their biodegradability and nontoxicity, bio-based materials have been proposed as potential material candidates in the field of electronics. Among these, cellulose nanocrystals (CNCs) have many interesting properties including biodegradability, high mechanical strength, and possibility to functionalize. In terms of electrical properties, CNCs are electrically insulated, limiting their potential in electronics. This work aims to build up a poly(o-toluidine)-like shell around the CNCs to render them conductive. For this goal, the surface of the CNCs was carbamated using 2,4-toluene diisocyanate through the para-isocyanates and the ortho-isocyanates were later hydrolyzed to amine groups using HCl-acidified dimethylsulfoxide. The resultant o-toluidine-like molecules on the CNC surface were then polymerized using ammonium persulfate to form an electrically conductive shell around each CNC. The resultant CNCs were then characterized for their chemical, morphological, and electrical properties. Fourier-transform infrared analysis of the CNCs at each stage confirmed the expected chemical changes upon carbamation, hydrolysis, and polymerization and X-ray diffraction confirmed the permanence of the native crystalline structure of the CNCs. The atomic force microscopy images showed that the obtained CNCs were on average slightly thicker than the original ones, possibly due to the growth of the poly(o-toluidine) shell around them. Finally, using the four-point method, the obtained CNCs were electrically conductive with a conductivity of 0.46 S/cm. Such novel electrically conductive CNCs should have great potential in a wide range of applications including electronics, sensing, and medicine.
... As explained in the following literature review, these conducting polymers have distinct and extensive uses in the medical field. Polyaniline may be used to detect cholesterol in blood via an enzymatic approach, and nonenzymatic detection of IgG in humans is viable by utilizing polyaniline gold nanospheres as nanolabels [73,74]. Noninvasive usage of a PPy layer on the gold surfaces of disposable screen-printed electrodes (SPE) utilizing 1H-pyrrole-1-propanoic acid revealed new applications for conductometric biosensors [75]. ...
Human antibodies are produced due to the activation of immune system components upon exposure to an external agent or antigen. Human antibody G, or immunoglobin G (IgG), accounts for 75% of total serum antibody content. IgG controls several infections by eradicating disease-causing pathogens from the body through complementary interactions with toxins. Additionally, IgG is an important diagnostic tool for certain pathological conditions, such as autoimmune hepatitis, hepatitis B virus (HBV), chickenpox and MMR (measles, mumps, and rubella), and coronavirus-induced disease 19 (COVID-19). As an important biomarker, IgG has sparked interest in conducting research to produce robust, sensitive, selective, and economical biosensors for its detection. To date, researchers have used different strategies and explored various materials from macro- to nanoscale to be used in IgG biosensing. In this review, emerging biosensors for IgG detection have been reviewed along with their detection limits, especially electrochemical biosensors that, when coupled with nanomaterials, can help to achieve the characteristics of a reliable IgG biosensor. Furthermore, this review can assist scientists in developing strategies for future research not only for IgG biosensors but also for the development of other biosensing systems for diverse targets.
... Different SPEs were prepared for the detection of 2,4-D using different amounts of MIP as an ionophore, TDMAC or Aliquat 336 as an anion exchanger, o-NPOE or DOP as a plasticizer, and PANI as a modifier, as in Table 2. Sensor 1 based on DOP as a plasticizer showed a sub-Nernst response (anionic slopes of 26.4 mV/decade) to 2,4-D in water over a small linear dynamic range (LDR) of 10 −4 to 10 −5 M with a limit of detection (LOD) of 1.0 × 10 −5 M, Figure 5. Changing the ion exchanger to Aliquate 336 in Sensor 2, caused a comparable slope within wider LDR and the same LOD of 1.0 × 10 −5 M. In sensor 3, o-NPOE was used as a plasticizer of a higher dielectric constant; it exhibited a slight improvement in the limit of detection compared with DOP used in sensor 2. Sensor 4 was fabricated using a drop-cast PAN layer as electrically conductive support followed by deposition (drop-casting) of the selective PVC membrane based on o-NPOE as a plasticizer to improve sensor performance; it showed a Nernst response of 29.9 mV/decade over LDR of 10 −2 -10 −6 M, and an improved detection limit of 8.8 × 10 −7 M. This good potentiometric response characteristics can be attributed to the high dielectric constant of the plasticizer (o-NPOE), in addition to the presence of the conductive layer that facilitates the electron transfer and improves the response [24,25]. ...
2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide worldwide. However, its residues in agricultural products are extremely harmful to human health and to the environment in soil and water. Previous methods for determining 2,4-D in water and soil samples are expensive, cumbersome, and not highly selective. In this study, we developed a novel disposal sensor based on screen-printed electrodes (SPEs) for detecting 2,4-D in wastewater and soil samples. The SPEs were modified with conductive polyaniline (PANI) layer and polyvinyl chloride (PVC) membrane loaded with molecularly printed polymer (MIP). The MIP particles were prepared using 2,4-D as template, methacrylic acid (MAA) as monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, and benzoyl peroxide as initiator. The best sensor shows a dynamic concentration range of 10−2 to 10−7 M 2,4-D, a detection limit (LOD) of 3.6 × 10−7 M, Nernst slope (response) of 29.9 mV/decade, and high selectivity over other interfering species previously reported in the literature. The sensors also achieved a short response time of 25 s, high reversibility, and a lifetime of over 2 weeks. The developed sensors were successfully used for determining 2,4-D in real wastewater and soil samples with high accuracy and precision.
... biosensors have maintained their ever-increasing relevance in the biosensors business, with considerable applications in healthcare diagnostics and research facilities. 54 The fundamental concept underlying amperometric glucose detection is explicitly illustrated in Eq. 1: glucose oxidase enzymes immobilized on bioelectrodes oxidize glucose molecules, resulting in the formation of peroxide, which is then electrochemically detected. ...
Biosensors are a rapidly expanding field of science owing to their wide variety of applications in healthcare, pharmacology, environmental control, food quality assessment, security and defense, and, most notably, diagnostics. Among various biosensors, electrochemical biosensors are immensely popular due to their high sensitivity, low detection limit, automation competence, low testing cost, and owing to the invention of electrochemical disposable devices capable of dealing with extremely tiny sample quantities. For efficient biosensor development, biomolecule immobilization is a key step which needs the transducer surface to be functionalized. In 2007, polydopamine (PDA) arises as a substrate independent coating material with the capability to functionalize both inorganic and organic surfaces. The chemical structure of PDA enriched with catechol, imine, and amine groups provide an ideal environment for dense immobilization of biomolecules on transducer surface and demonstrates to be simple, accessible, and mild strategy for biosensor design. This review attempts to assemble existing research progressed on PDA-based electrochemical biosensors in terms of enzymatic biosensors (based on H2O2, glucose, alcoholic and laccase), genosensors (DNA sensing), immunosensors and aptasensors. In addition, literature on biosensing of thrombin, tumor indicators, amino acids, and other clinically important analytes has been compiled to offer a thorough review of PDA-based biosensors.
... In recent years, organic semiconductors have been researched for electrochemical determination applications because of their adaptable conducting nature and versatile applications in high-performance electronics [1][2][3]. Among the various organic semiconductors, PAni has been demonstrated to be a very efficient, non-toxic, low-cost electrode material and is especially suitable for electrochemical sensing applications [4][5][6][7]. Still, the mechanism of electrochemical determination of various analytes using PAni as an electrode material has yet to be fully explained [8,9]. ...
... Finally, the NO 3 − determination mechanism of the GA@PAni-CNT electrode was construed in detail. 6 ], 5% solution of Nafion ® , and dimethylformamide (DMF) were chemicals of high purity, and were purchased from Sigma-Aldrich, Taufkirchen, Germany. Edible GA was purchased from the local market in Jeddah, Saudi Arabia. ...
... The mixture stirred continuously until the color changed from pale yellow to green. The formed nanocomposite was isolated by centrifugation and washed several times with water to maintain a neutral pH range (6)(7). The obtained precipitates were then placed in the vacuum oven at 100 • C for overnight which resulted in black powder. ...
Significant agricultural and industrial activities necessitate the regular monitoring of
nitrate (NO3−) ions levels in feed and groundwater. The current comparative study discloses an innovative user-friendly electrochemical approach for the determination of NO3− over polyaniline (PAni)-based modified electrodes. The electrochemical sensors concocted with PAni, multi-walled carbon nanotubes (CNT), and gum arabic (GA). The unique electrode material GA@PAni-CNT was synthesized by facile one-pot catalytic polymerization of aniline (Ani) with FeCl3/H2O2 in the presence of CNT and GA as integral components. As revealed by cyclic voltammetry (CV), the anchoring/retention of NO3− followed by reduction is proposed to occur when a GA@PAniCNT electrode is immersed in phosphate buffer electrolyte containing NO3− that eventually results
in a significantly higher redox activity of the GA@PAni-CNT electrode upon potential scan. The mechanism of NO3− anchoring may be associated with the non-redox transition of leucomeraldine salt (LS) into emeraldine salt (ES) and the generation of nitrite (NO2−) ions. As a result, the oxidation current produced by CV for redox transition of ES to pernigraniline (PN) was ~9 times of that obtained with GA@PAni-CNT electrode and phosphate buffer electrolyte, thus achieving indirect NO3− voltammetric determination of the GA@PAni-CNT electrode. The prepared GA@PAni-CNT electrode displayed a higher charge transfer ability as compared to that of PAni-CNT and PAni electrodes. The optimum square wave voltammetric (SWV) response resulted in two linear concentration ranges of 1–10 (R2 = 0.9995) and 15–50 µM (R2 = 0.9988) with a detection limit of 0.42 µM, which is significantly lower. The GA@PAni-CNT electrode demonstrated the best detection, sensitivity, and performance among the investigated electrodes for indirect voltammetric determination of NO3− that portrayed the possibility of utilizing GA—stabilized PAni and CNT nanocomposite materials in additional electrochemical sensing applications.
Citation: Kosa, S.A.M.; Khan, A.N.; Ahmed, S.; Aslam, M.; Bawazir, W.A.; Hameed, A.; Soomro, M.T. Strategic Electrochemical Determination of Nitrate over Polyaniline/Multi-Walled Carbon Nanotubes-Gum Arabic Architecture. Nanomaterials 2022, 12, 3542. https://doi.org/10.3390/nano12193542
