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In aquatic environment, the presence of heavy metal in excess than permissible limits set by the World Health Organization (WHO) can cause problems to human being and aquatic life. Hence, various analytical methods have been developed to monitor the water quality by tracing different heavy metal ions in water samples. The present review summarizes...
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... These methods include potentiometry, amperometry, differential pulse voltammetry (DPV), square wave voltammetry (SWV), differential pulse anodic stripping voltammetry (DPASV), square wave anodic stripping voltammetry (SWASV), cyclic voltammetry (CV), and electrochemical impedance Ionics spectroscopy (EIS). Recently these methods received much attention owing to their fast response, easy procedure, cost effectiveness, high S/N ratio, high sensitivity, and selectivity [8]. Additionally, the use of SWASV for HMIs detection has secured wider preference due to its high sensitivity. ...
This work elucidates the synthesis of V2O5, Praseodymium (Pr) doped vanadium pentoxide Pr-V2O5 nanoparticles (NPs) and Pr-V2O5/rGO nanocomposite by green combustion method, using Manilkara zapota as a novel combustion fuel. The synthesised Pr-V2O5/rGO nano catalyst was characterized by various physicochemical techniques. Pr-V2O5/rGO exhibits an excellent electrochemical ability to detect Pb²⁺ with lower limit of detection 2.919 nM and sensitivity 0.8113 μA/nM cm². Further, the Pr-V2O5/rGO employed for the photocatalytic degradation of MB dye displayed remarkable efficiency through swift degradation. Also, the conditions such as catalytic load, pH, and dye concentration were optimized to achieve most efficient degradation of the dye. Pr-V2O5 provides a greater number of catalytic sites and high ion transport channels, whereas rGO provides the conductivity and porosity to the nanocatalyst. By utilizing these synergic advantages, Pr-V2O5/rGO nanocatalyst effectively detects heavy metal ions (HMIs) and degrade methylene blue (MB) dye, befitting from unique morphology of Pr doped V2O5 nanoparticles wrapped into the two dimensional rGO nano sheets. The above results limelight that Pr-V2O5/rGO as the multifunctional catalyst for promising detection of hazardous metal ions and effective environmental remediation.
... There are numerous health hazards associated with heavy metal ions, both for humans and for ecosystems. The development of a rapid, sensitive, accurate, and convenient method for detecting heavy metal ions can have significant theoretical and practical implications [1]. A variety of methods have been developed to analyze heavy metal ions, including atomic absorption spectroscopy [2], inductively coupled plasma-optical emission, and mass spectrometry [3,4]. ...
Through the manipulation of electrospinning solution properties, we tuned the morphology and porosity of electrospun titanium dioxide (TiO2) nanofibers. Using a modified glassy carbon electrode (GCE) with TiO2 nanofibers and Ag-coated carbon nanofibers (AgCNFs) with nafion as a binder, heavy metal ions (HMIs) have been detected with nanomolar detection limits using square wave anodic stripping voltammetry (SWASV). It has been determined how the Cd²⁺ current signal responds to changes in deposition potential, deposition time, buffer solution pH, and drop-cast volume. The estimated sensitivity of Cd²⁺ is 49.98 µA µM⁻¹ and the limit of detection (LOD) is found to be 12.75 nM by the three-sigma (3σ) method. The TiO2/AgCNF/nafion/GCE electrode can simultaneously detect Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ ions without mutual interference. The sensitivities toward Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ are 39.59, 42.75, 15.67, and 10.52 µA µM⁻¹, respectively. The LOD toward Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ are 40.14, 31.69, 93.31, and 208.26 nM, respectively. These quantities fall far short of the WHO’s recommended guideline values. This combination of very porous TiO2 nanofiber with AgCNF leads to an innovative sensor platform that has very low LOD compared to the previous sensors that have been reported.
Graphical abstract
... Research efforts have particularly focused on the interaction between calixarenes, especially those with oxygen donor atoms on the lower rim, and metal cations, predominantly alkali and alkaline earths [4,18,19]. Moreover, calixarenes functionalized with both N-donor and O-donor atoms have been investigated for their effectiveness in complexing transition metals [16,20], heavy metals [16,21], and lanthanide cations [18,22]. Further enhancements to calixarene properties have been explored through modifications involving the incorporation of 2-pyridyl-methyl pendant groups on the lower rim. ...
This paper investigates pseudo-polymorphism in 2-pyridylmethoxy derivatives of p-tert-butylcalix[4]arene (PyC4), p-tert-butyldihomooxa-calix[4]arenes (PyHOC4), and p-tert-butylhexahomotrioxacalix[3]arenes (PyHO3C3), presenting 11 crystal structures with 15 crystallographically independent molecules. The macrocycle of PyC4 is smaller and less flexible with respect to those of PyHOC4 and PyHO3C3, and in solution, the cone conformation of these three molecules exhibits different point symmetries: C4, Cs, and C3, respectively. A correlation is observed between the macrocycle’s structural rigidity and the number of pseudo-polymorphs formed. The more rigid PyC4 displays a higher number (six) of pseudo-polymorphs compared to PyHOC4 and PyHO3C3, which exhibit a smaller number of crystalline forms (three and two, respectively). The X-ray structures obtained show that the conformation of the macrorings is primarily influenced by the presence of an acetonitrile guest molecule within the cavity, with limited impact from crystal packing and intermolecular co-crystallized solvent molecules. Notably, both calix[4]arene derivatives produce a host–guest complex with acetonitrile, while the most flexible and less aromatic PyHO3C3 does not give crystals with acetonitrile as the guest. Intertwined 1D and 2D solvent channel networks were observed in the PyHOC4-hexane and in the PyHO3C3-H2O-MeOH crystal structures, respectively, while the other pseudopolymorphs of PyHOC4 and PyHO3C3 and all PyC4 crystal forms exhibit closely packed crystal structures without open channels.
... Research efforts have particularly focused on the interaction between calixarenes, especially those with oxygen donor atoms on the lower rim, and metal cations, predominantly alkali and alkaline earths [4,8,9]. Moreover, calixarenes functionalized with both N-donor and O-donor atoms have been investigated for their effectiveness in complexing transition metals [10,11], heavy metals [11,12] and lanthanide cations [8,13]. Further enhancements to calixarene properties have been explored through modifications involving the incorporation of 2-pyridyl-methyl pendant groups on the lower rim. ...
This paper investigates pseudo-polymorphism in 2-pyridylmethoxy derivatives of p-tert-butylcalix[4]arene (PyC4), p-tert-butyldihomooxa-calix[4]arenes (PyHOC4), and p-tert-butylhexahomotrioxacalix[3]arenes (PyHO3C3), presenting 11 crystal structures with 15 crystallographically independent molecules. The macrocycle of PyC4 is smaller and less flexible with respect to those of PyHOC4 and PyHO3C3 and in solution, the cone conformation of these three molecules exhibit different point symmetries: C4, Cs and C3, respectively. A correlation is observed between the macrocycle's structural rigidity and the number of pseudo-polymorphs formed. The more rigid PyC4 displays a higher number (6) of pseudo-polymorphs compared to PyHOC4 and PyHO3C3, which exhibit a smaller number of crystalline forms (3 and 2, respectively). The X-ray structures obtained show that the conformation of the macrorings is primarily influenced by the presence of an acetonitrile guest molecule within the cavity, with limited impact from crystal packing and intermolecular cocrystallized solvent molecules. Notably, both calix[4]arene derivatives produce host-guest complex with acetonitrile, while the most flexible and less aromatic PyHO3C3 do not give crystals with acetonitrile as guest. Intertwined 1D and 2D solvent channel networks were observed in the PyHOC4-hexane and in the PyHO3C3-H2O-MeOH crystal structures, respectively, while the other pseudopolymorphs of PyHOC4 and PyHO3C3 and all PyC4 crystal forms exhibit a closely packed crystal structures without open channels.
... [9,10] Various research reports about calixarene as an ion sensor have provided a breakthrough for the detection of various ions. [11,12] In recent years, there has been a development in the detection of nitroaromatic compounds by the use of calixarene. [13] To design a ligand attached to the basic calixarene moiety, for the detection of explosives, we need to consider the desired functionality and properties. ...
A novel pyrene appended supramolecular assembly (PAOC) has been fabricated by reacting intermediate‐pyren‐1‐ylmethyl 2‐chloroacetate (PMCA) with oxacalix[4]arene and characterized by 1H NMR, 13 C NMR and ESI‐Mass. PAOC works as fluorescent chemosensor for the selective detection of nitroaromatic compounds such as 4‐nitrophenol (4NP) and 2,4,6‐trinitrophenol (TNP). The binding mechanism between PAOC and the analytes were investigated through various spectroscopic techniques, and the results indicate a strong interaction between the two. The fluorescence intensity of PAOC is quenched upon interaction with nitroaromatic compounds due to a photoinduced electron transfer process, which was validated by DFT calculations. The sensor exhibits excellent selectivity and sensitivity towards TNP over other nitroaromatic compounds. The detection limits for TNP and 4NP were found to be 1.6 μM and 1.9 μM, respectively. PAOC's detection results in real water samples are remarkable. This study provides a new approach to develop highly selective and sensitive chemosensor for the detection of nitroaromatic compounds, which have significant environmental and health hazards.
... Calixarene-based nanostructures are especially useful for delivering proteins, peptides, and genes [26] while simultaneously recognizing metallic ions with high sensitivity and specificity [27,28]. In order to create nanocapsules, nanosheets, nanotubes, and rotaxanes, calixarenes were used as the foundational building blocks [29][30][31][32][33][34][35]. ...
Calixarenes have always captured the attention of several researchers. They have the ability to entrap multiple molecules and form inclusion complexes with drugs due to their unique structure. Due to this property, they are being widely used in the development of several classes of drugs, most notably anticancer drugs. This review attempted to summarize the potential applications of calixarenes and its derivatives in the development of anticancer drugs, with a focus on the delivery of drug classes such as DNA intercalators, taxanes, DNA alkylators, and topoisomerase inhibitors. Calixarene-based macromolecular chemistry could therefore have a high potential for overcoming the toxicity of cancer chemotherapy and achieving targeted drug delivery.
... However, as already mentioned, researchers' interest in recent years has focused on the identification of heavy metal ions with the help of various electrochemical methods, particularly voltammetry, as it is an easy, fast, and relatively inexpensive way to determine them compared to other analytical methods. Although previous techniques are very sensitive and selective, due to the limitations they cause, electrochemical methods such as voltammetry are preferred for the detection of heavy metal ions, which, in contrast to previous techniques, have the advantages of low cost, simplicity, ease of operation, fast analysis, portability, the ability to monitor environmental samples in the field, and high sensitivity and selectivity [13]. Electrochemical techniques, especially voltammetry, involve electroanalytical methods for the determination of one or more analytes by measuring the current as a function of potential. ...
The detection of toxic heavy metal ions, especially cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu), is a global problem due to ongoing pollution incidents and continuous anthropogenic and industrial activities. Therefore, it is important to develop effective detection techniques to determine the levels of pollution from heavy metal ions in various media. Electrochemical techniques, more specifically voltammetry, due to its properties, is a promising method for the simultaneous detection of heavy metal ions. This review examines the current trends related to electrode formation and analysis techniques used. In addition, there is a reference to advanced detection methods based on the nanoparticles that have been developed so far, as well as formation with bismuth and the emerging technique of screen-printed electrodes. Finally, the advantages of using these methods are highlighted, while a discussion is presented on the benefits arising from nanotechnology, as it gives researchers new ideas for integrating these technologies into devices that can be used anywhere at any time. Reference is also made to the speciation of metals and how it affects their toxicity, as it is an important subject of research.
... While DNA-zyme based biosensors are also capable of specific detection of some metal ions due to their catalytic reaction and cleavage of DNA [18,19]. However, organic ionophores are the subject of several studies, and calix [4]arene derivatives are some of the researched selective ionophores for lead detection [20][21][22]. ...
We aim to develop an electrochemical sensor for a divalent metal ion (lead II), a highly toxic water contaminant. We explore a sensor formed with a hemicellulose polysaccharide extracted from the Opuntia Ficus Indica cactus associated with agarose as a sensitive layer deposited on a gold electrode. This sensor combines the functional groups of hemicellulose that could form a complex with metal ions and agarose with gelling properties to form a stable membrane. The sensor demonstrated a loading ability of Pb2+, with higher affinity compared to other metal ions such as Hg2+, Ni2+, and Cu2+, thanks to the chemical structure of hemicellulose. The detection was measured by square wave voltammetry based on a well-defined redox peak of the metal ions. The sensor shows high sensitivity towards Pb2+ with a detection limit of 1.3 fM. The application in river and sea water using the standard addition method for lead detection was studied.
... Heavy metals (HM) viz., lead (Pb), copper (Cu), mercury (Hg), zinc (Zn), cadmium (Cd), and chromium (Cr) are extensively used in various industries such as electroplating, leather, paints, pigments, batteries, and alloys. Industrial dependence on HM has resulted in the accumulation of these toxic metals in the natural ecosystem at alarming rates [1,2]. Consequently, bioaccumulation cause poisoning and damages the brain, lungs, liver, and kidneys and is even fatal at higher concentrations [3]. ...
Heavy metals (HM) have gained significant attention in terms of regular monitoring and detection owing to their toxicity, non-biodegradability, and persistence. Current techniques for detecting HM are expensive, cumbersome, and require sophisticated instruments and skilled labor. Hence, developing cheap, rapid, energy-efficient, and accurate sensors is imperative and electrochemical techniques have emerged as promising tools. The current study involves the fabrication of an electrochemical sensor for the concurrent detection of lead (Pb2+) and cadmium (Cd2+) ions using modified carbon paste electrodes (mCPE). Activated carbon (AC) with a BET surface area of 1118 m2 g-1 was obtained by chemical activation and thermal treatment of the waste rubberwood sawdust. AC-Graphite, AC-Reduced Graphene Oxide (RGO), and AC-RGO-Chitosan were the types of mCPEs that were utilized. The electrochemical behaviors and effects of pH, concentration, and scan rate were studied using Cyclic voltammetry (CV). Studies on detection were conducted using CV and linear sweep voltammetry. Although all the 3 mCPEs detected Cd2+ and Pb2+ in the simulated wastewater, the CPE with RGO and AC could detect Cd2+ as low as 10.91 µg L-1 and Pb2+ as low as 14.01 µg L-1. The work explored the possibility of using AC as a potential sustainable substitute for graphite in CPE.
... Kissinger & Heinemann [152], Bard et al. [153], Mei et al. [156], and Harvey [157]. A general overview based on the mentioned references is summarized in the following diagram in Figure 10: First, a distinction must be made between those techniques that are applied within the solution and those that focus on the study of the processes that occur at the interface between the solution and the electrode. ...
Neural precursor cells have enormous potential for developing effective therapies for previously untreatable pathologies due to their ability to form different specialized cells. However, their translation to clinical routine is complicated due to specific and complex physiological, chemical, and electrical stimuli. In this work, we aimed at nerve regeneration in vitro through neural precursor cells. We evaluated bio-potentiating substrates and cell membrane matrices to provide neural precursor cells with the mechanical and physiological support necessary for their proliferation. We have employed pharmacological treatment, electrostimulation, and optogenetic stimulation to modulate their development and differentiation, with promising results. To combine these techniques, we have designed electronic systems that allow the application of these techniques in vitro. Specifically, we have designed and validated a novel technology for the electrically controlled release of drugs based on mesoporous silica nanoparticles and bipyridine-heparin molecular gates, which we have validated through the controlled release of rhodamine in HeLa cell cultures. We have also designed devices for electrostimulation and optogenetic stimulation, validating them by applying different electrical stimuli and through real-time imaging of the transient responses of cells upon irradiation, respectively. In addition, we have developed electronic instrumentation capable of simultaneously measuring several biosensors based on field effect transistors functionalized with aptamers. This instrumentation could enable the implementation of closed-loop control of modulation techniques for neural precursor cell development by selectively measuring biomolecules in real-time, such as serotonin secretion, an early biochemical response indicator of elongation and neuronal differentiation in precursor cells. These developments represent significant progress in stem cell research and can contribute to developing effective therapies for previously untreatable pathologies, such as spinal cord injury.
