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Room temperature x- ray powder diffraction pattern reveals that the structure is monoclinic Infrared spectra was used check the functional groups. Thermal analysis technique indicates that the compound undergoes a structural phase... more
Room temperature x- ray powder diffraction pattern reveals that the structure is monoclinic Infrared spectra was used check the functional groups. Thermal analysis technique indicates that the compound undergoes a structural phase transition at 308K. Moreover, the complex dielectric permittivity e*(e *= έ - jє˝) and the ac conductivity are measured as function of temperature (100K <T < 400K) and at some selected frequencies The data indicate that the frequency dependent conductivity seems to be in accordance with the power law The charge transport mechanism follows the quantum mechanical tunneling (QMT) model.
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ABSTRACT New plastic membrane electrodes for pipazethate hydrochloride based on pipazethatium phosphotungstate, pipazethatium phosphomolybdate and a mixture of the two were prepared. The electrodes were fully characterized in terms of... more
ABSTRACT New plastic membrane electrodes for pipazethate hydrochloride based on pipazethatium phosphotungstate, pipazethatium phosphomolybdate and a mixture of the two were prepared. The electrodes were fully characterized in terms of composition, life span, pH and temperature and were then applied to the potentiometric determination of the pipazethate ion in its pure state and pharmaceutical preparations under batch and flow injection conditions. The selectivity of the electrodes towards many inorganic cations, sugars and amino acids was also tested.
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Research Interests: Materials Engineering, Materials Science, Chemistry, Analytical Chemistry, Electrochemistry, and 15 moreNanoparticle, Graphene, Carbon Nanotube, Cyclic Voltammetry, bisphenol A, Dielectric Spectroscopy, Cyclodextrin, RSC, Analytical Methods, Electrode, Naloxone, Electrochemical sensor, Colloidal Gold, Differential Pulse Voltammetry, and Pyrrole
Due to the current global SARS-CoV-2 pandemic, rapid and accurate diagnostic tools are needed to prevent the spread of COVID-19 across the globe. An electrochemical sensing platform was constructed using CNTs/WO3-screen printed electrodes... more
Due to the current global SARS-CoV-2 pandemic, rapid and accurate diagnostic tools are needed to prevent the spread of COVID-19 across the globe. An electrochemical sensing platform was constructed using CNTs/WO3-screen printed electrodes for imprinting the complete virus particles (SARS-CoV-2 particles) within the polymeric matrix to create viral complementary binding sites. The sensor provided high selectivity toward the target virus over other tested human corona and influenza respiratory interference viruses. The sensitivity performance of the sensor chips was evaluated using different viral concentrations, while the limits of detection and quantification were 57 and 175 pg/mL, respectively. Reaching this satisfied low detection limit (almost 27-fold more sensitive than the RT-PCR), the sensor was applied in clinical specimens obtained from SARS-CoV-2 suspected cases. Thus, dealing directly with clinical samples on the chip could be provided as a portable device for instantaneous and simple point of care in hospitals, airports, and hotspots.
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We report here for the first time on the use of Molecularly Imprinted Polymers as modifiers in bulk optodes, Miptode, for the determination of a pharmaceutical compound, itopride hydrochloride as an example in a concentration range of... more
We report here for the first time on the use of Molecularly Imprinted Polymers as modifiers in bulk optodes, Miptode, for the determination of a pharmaceutical compound, itopride hydrochloride as an example in a concentration range of 1×10(-1)-1×10(-4)molL(-1). In comparison to the optode containing the ion exchanger only (Miptode 3), the optode containing the ion exchanger and the MIP particles (Miptode 2) showed improved selectivity over the most lipophilic species, Na(+) and K(+), by more than two orders of magnitude. For instance, the optical selectivity coefficients using Miptode 2, [Formula: see text] , were as follow: NH4(+)˂-6; Na(+)=-4.0, which were greatly enhanced in comparison with that obtained by Miptode 3. This work opens a new avenue for using miptodes for the determination of all the pharmaceutical preparations without the need for the development of new ionophores.
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A transdermal drug-delivery coaxial nanofibers-based system was developed for the delivery of varenicline (VAR) for smoking cessation. The nanofibers contain exit channels to allow the release of VAR.
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Herein, we present the utilization of Ni2+-doped, amine-functionalized, UiO-66-NH2 metal–organic framework (MOF) nanoparticles deposited onto multi-walled carbon nanotubes (MWCNTs) as a precursor to generate electrocatalytically active... more
Herein, we present the utilization of Ni2+-doped, amine-functionalized, UiO-66-NH2 metal–organic framework (MOF) nanoparticles deposited onto multi-walled carbon nanotubes (MWCNTs) as a precursor to generate electrocatalytically active catalyst towards methanol (MeOH) oxidation. The electrode material displayed an onset potential of 0.42 V (vs Hg/HgO) with maximum activity at 1 M MeOH concentration (143 mA/cm2 current density at 0.6 V vs Hg/HgO). The catalyst also demonstrated high stability, retaining 93.5% of its initial activity under continuous electrolysis for 1 h, and 84.1% after 10 h.
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In this work, the synthesis and optimization of an electrochemical sensor based on gold nanoparticles (AuNPs)/ conducting poly Congo red dye (poly(CR)) nanocomposite is reported and applied for detection of the Oxazolidinone fungicide... more
In this work, the synthesis and optimization of an electrochemical sensor based on gold nanoparticles (AuNPs)/ conducting poly Congo red dye (poly(CR)) nanocomposite is reported and applied for detection of the Oxazolidinone fungicide famoxadone (FAM), which is considered as an environmentally hazardous material on excessive uncontrolled application. The modified sensor was characterized electrochemically using Cyclic Voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to investigate the nature of charge transfer upon modification. Also, the topography of the sensor was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDX). Two linear ranges 0.001–1 μM (0.37–374.40) μg l−1 and 3–100 μM (1.12–37.44) mg l−1 were recorded using AuNPs/poly (Congo Red)/GCE sensor for FAM with limit of detection (LOD) of 0.17 nM (0.06 μg l−1) and limit of quantification (LOQ) of 0.48 nM (0.18 μg l−1). The tested sens...
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Alanine amino transaminase (ALT) is an enzyme that can be used as a biomarker for liver injury and other diseases. In this work, we report the development of the first microelectrode based on a molecularly imprinted pyruvate oxidase... more
Alanine amino transaminase (ALT) is an enzyme that can be used as a biomarker for liver injury and other diseases. In this work, we report the development of the first microelectrode based on a molecularly imprinted pyruvate oxidase enzyme to be applied as an electrochemical biosensor for ALT detection. The biosensor is based on pyruvate oxidase enzyme (POx), imprinted using 4-aminophenol (functional monomer-on-platinum microelectrode modified (PME)) with platinum nanoparticles and 4-aminoantypirine (4-AAP)/sodium pyruvate as an electrochemical indicator. The operational conditions of the biosensor were optimized and characterized morphologically using scanning electron microscopy (SEM) and electrochemically using electrochemical impedance spectroscopy (EIS). The biosensor was found to have a fast response towards ALT within a linear range of 25–700 U/L and a limit of detection of 2.97 U/L. The biosensor did not exhibit cross-reactivity towards other tested enzymes, including nicoti...
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Acetamiprid (ACP) is a widely used systemic insecticide as a replacement for organophosphorus compounds to control sucking-type insects on leafy vegetables, fruits, and tea trees. In this work, bulk polymerized molecularly imprinted... more
Acetamiprid (ACP) is a widely used systemic insecticide as a replacement for organophosphorus compounds to control sucking-type insects on leafy vegetables, fruits, and tea trees. In this work, bulk polymerized molecularly imprinted polymer was developed using ACP as template, 4-Vinyl pyridine as monomer and ethylene glycol dimethyl acrylate (EGDMA) as cross-linker in presence of acetone as porogen. The polymers were then tested as a template recognition modifiers for carbon paste electrode in cooperation with multiwalled carbon nanotubes as a signal enhancer. The optimum response towards ACP was attained on using 10% of polymer ratio (1: 3: 40) and 5% MW-CNT in the electrode composition at pH 6.2 of 0.1 phosphate buffer as supporting electrolyte. The developed electrode was morphologically and electrochemically characterized and was found to show a linear response for differential pulse voltammetry of 1 × 10−12–5 × 10−6 M equivalent to 0.222–111.3 ×104 ng l−1 with limits of detecti...
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In recent years, due to the developments in the textile industry, water contaminated with synthetic dyes such as methylene blue (MB) has become an environmental threat based on the possible impacts in terms of chemical and biochemical... more
In recent years, due to the developments in the textile industry, water contaminated with synthetic dyes such as methylene blue (MB) has become an environmental threat based on the possible impacts in terms of chemical and biochemical demand, which leads to disturbance in aquatic plants photosynthesis, besides their possible toxicity and carcinogenicity for humans. In this work, an adsorbent hydrogel is prepared via free radical polymerization comprising acrylic acid (PAA) as a monomer and orange peel (OP) as a natural modifier rich in OH and COOH present in its cellulose and pectin content. The resulting hydrogels were optimized in terms of the content of OP and the number of cross-linkers and characterized morphologically using Scanning electron microscopy. Furthermore, BET analysis was used to follow the variation in the porosity and in terms of the surface area of the modified hydrogel. The adsorption behavior was found to follow pseudo-second-order as a kinetic model, and Langm...
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A bacterial imprinted polymer (BIP)-based biosensor was designed and fabricated for rapid and selective detection of Salmonella typhimurium in minced beef meat.
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Foot-and-mouth disease virus serotype South-Africa territories-2 (FMDV-SAT-2) is the most fastidious known type in Aphthovirus which is subsequently reflected in the diagnosis regime. Rapid and early diagnostic actions are usually taken... more
Foot-and-mouth disease virus serotype South-Africa territories-2 (FMDV-SAT-2) is the most fastidious known type in Aphthovirus which is subsequently reflected in the diagnosis regime. Rapid and early diagnostic actions are usually taken in response to the FMDV outbreak to prevent the dramatic spread of the disease. Virus imprinted sensor (VIP sensor) is gathering huge attention for the selective detection of pathogens. Thus, the whole virus particles of SAT-2 together with an electropolymerized film of poly(o-phenylenediamine) (PoPD) on gold-copper modified screen-printed electrode were applied to fabricate SAT-2-virus imprinted polymer (SAT-2-VIP). The SAT-2-VIPs were fully characterized using cyclic voltammetry (CV), linear sweep voltammetry (LSV), Atomic force microscopy (AFM), Scanning electron microscope (SEM), and Fourier transform Infra-Red (FTIR) spectroscopy. Excellent selective binding affinity towards the targeted virus particle was achieved with limits of detection and quantification of 0.1 ng/mL and 0.4 ng/mL, respectively. In terms of viral interference, the sensor did not show cross-reactivity towards other animal viruses including FMDV serotype A, O, or even SAT-2 subtype Libya and the un-related virus Lumpy skin disease virus (LSDV). This high selectivity provides a sensible platform with 70 folds more sensitivity than the reference RT-PCR as revealed from the application of SAT-2-VIP sensor for rapid analysis of clinical samples with no need for treatment or equipped labs. Thus, as diagnostic and surveillance technologies, on-site point of care diagnostics for SAT-2 virus are supported.
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A simple and sensitive conductimetric method for the determination of salbutamol sulphate and reproterol and pipazethate hydrochlorides is presented based on their ion associates with phosphotungstic and phosphomolybdic acids. The effect... more
A simple and sensitive conductimetric method for the determination of salbutamol sulphate and reproterol and pipazethate hydrochlorides is presented based on their ion associates with phosphotungstic and phosphomolybdic acids. The effect of solvent, molar ratio, reagent concentration and temperature were studied, and the solubility products of the formed ion associates were calculated. The method was applied to the determination of the drugs in their pure state or pharmaceutical preparations with mean recovery values of 99.82-100.54, 99.75-100.12 and 99.95-100.40%, and coefficient of variation 0.28-0.52, 0.16-0.36 and 0.19-0.33 for salbutamol sulphate, reproterol HCl and pipazathate HCl, respectively.
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Different hexoprenaline () conventional and coated wire electrodes were constructed and evaluated. Membranes were based on hexoprenalinium phosphotungstate (Hx-PTA) and hexporenalinium phosphomolybdate (Hx-PMA). The electrodes were fully... more
Different hexoprenaline () conventional and coated wire electrodes were constructed and evaluated. Membranes were based on hexoprenalinium phosphotungstate (Hx-PTA) and hexporenalinium phosphomolybdate (Hx-PMA). The electrodes were fully characterized in terms of their composition, response time, life span, pH, and temperature and then were applied to the potentiometric determination of the hexoprenalinium ion in its pure state, pharmaceutical preparations, and biological samples, urine and plasma, under batch and flow injection conditions. The selectivity of the electrodes towards many inorganic cations, sugars, amino acids, and some other brochodilatures of close chemical composition was also tested.
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A new validated potentiometric method is described for batch and continuous quality control monitoring of the drug oseltamivir phosphate (Taminil) (OST). The method involves the development of a potentiometric sensor responsive to the... more
A new validated potentiometric method is described for batch and continuous quality control monitoring of the drug oseltamivir phosphate (Taminil) (OST). The method involves the development of a potentiometric sensor responsive to the drug based on the use of the ion‐association complex of (OST+) cation with phosphomolybdate anion (PMA−) as an electroactive material in a poly(vinyl chloride) matrix membrane plasticized with o‐nitrophenyloctyl ether (o‐NPOE). Optimization of the performance characteristics of the sensor is described. A membrane incorporating the OST‐PMA‐NPOE complex in a tubular flow through detector is used in a two channel flow injection set up for continuous monitoring of the drug at a frequency of ∼30 samples h−1. The sensor shows fast near‐Nernstian response for OST over the concentration range 5.2×10−5–0.8×10−2 M (21.34 µg mL−1–3.23 mg mL−1) with a detection limit of 9.1×10−6 M (3.73 µg mL−1) over the pH range 4.6–6.1. The sensor displays good selectivity for O...
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A transdermal drug-delivery coaxial nanofibers-based system was developed for the delivery of varenicline (VAR) for smoking cessation. The nanofibers contain exit channels to allow the release of VAR.
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Different hexoprenaline (Hx2SO4) conventional and coated wire electrodes were constructed and evaluated. Membranes were based on hexoprenalinium phosphotungstate (Hx-PTA) and hexporenalinium phosphomolybdate (Hx-PMA). The electrodes were... more
Different hexoprenaline (Hx2SO4) conventional and coated wire electrodes were constructed and evaluated. Membranes were based on hexoprenalinium phosphotungstate (Hx-PTA) and hexporenalinium phosphomolybdate (Hx-PMA). The electrodes were fully characterized in terms of their composition, response time, life span, pH, and temperature and then were applied to the potentiometric determination of the hexoprenalinium ion in its pure state, pharmaceutical preparations, and biological samples, urine and plasma, under batch and flow injection conditions. The selectivity of the electrodes towards many inorganic cations, sugars, amino acids, and some other brochodilatures of close chemical composition was also tested. Copyright © 2008 Rasha M. El-Nashar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1.
Ivabradine hydrochloride (IVR) is a medically important drug because of its ability to lower the heart rate. Techniques reported for IVR determination were expensive, laborious, besides being of poor selectivity. In this study, iron oxide... more
Ivabradine hydrochloride (IVR) is a medically important drug because of its ability to lower the heart rate. Techniques reported for IVR determination were expensive, laborious, besides being of poor selectivity. In this study, iron oxide @ carbon nanotube (Fe2O3@MWCNTs) nanocomposite and molecularly imprinted polymer (MIP) were synthesized and used in the fabrication of carbon paste electrodes (CPEs) for the potentiometric detection of IVR in biological and pharmaceutical samples. CPEs of the best sensor were formulated from graphite (41 wt%) as a carbon source, MIP (3 wt.%) as an ionophore, Fe2O3@MWCNTs (5 wt%) as a modifier, and nitrophenyl octyl ether (NPOE, 51 wt.%) as a conductive oil so-called plasticizer. The best sensor exhibits a Nernstian slope (response) of 56 mV decade–1 within the IVR concentration range from 1.0 × 10–3 M to 9.8 × 10–8 M with high selectivity against interfering species (ascorbic, maltose, glucose, lactose, dopamine, glycine) over those reported earlie...
A computational approach was developed to find a suitable functional monomer to design a new molecularly imprinted polymer (MIP), based on which methacyrlic acid (MAA) was selected as a functional monomer to synthesize the molecular... more
A computational approach was developed to find a suitable functional monomer to design a new molecularly imprinted polymer (MIP), based on which methacyrlic acid (MAA) was selected as a functional monomer to synthesize the molecular imprinted and non-imprinted polymers. All calculations were carried out using Gaussian 03 software based on the application of HartreeFock (HF) method with 6-31G (d) basis set. The performance of the MIPs prepared with different ratios of MAA was then evaluated using equilibrium rebinding assays. The MIP with the highest binding capacity was chosen as recognition material for the fabrication of new PVC sensors and their responses were compared with each other and with previously reported modifiers in literature. The addition of the ionic surfactant (TFPB) was found to have a synergistic effect on the response mechanism of the electrodes. The results of the MIP modified sensors show that they provide an improved electrode slope, wider pH range and a highly extended life time reaching 7 months compared to 2–4 weeks in case of traditional ion-exchangers reported in literature, besides, being successfully applied for measurements in biological samples.
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... 249 1573-4110/09 $55.00+.00 © 2009 Bentham Science Publishers Ltd. Applications of Calixarenes as Potential Ionophores for Electrochemical Sensors Rasha M. El Nashar 1 , Hebat Allah A. Wagdy 1 , and Hassan Y. Aboul-Enein 2,* ...
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A new potentiometric electrochemical sensor (ion-selective electrode) based on the formation of ion associate of Imatinib mesylate with sodium tetraphenyl borate in polyvinyl chloride plactisized with dioctylphythalate was developed .Such... more
A new potentiometric electrochemical sensor (ion-selective electrode) based on the formation of ion associate of Imatinib mesylate with sodium tetraphenyl borate in polyvinyl chloride plactisized with dioctylphythalate was developed .Such electrode was prepared for the assay of the cited drug in its pure form and pharmaceutical formulations under batch and flow injection analysis conditions. The life span of the electrode is 30 days on continuous soaking and several months when kept in dry conditions. It is characterized by usable concentration range of (1.0×10 -5 -1.0×10 -3 M) and (5.0×10 -6 1.0×10 -2 M) in batch and FIA conditions, respectively. The change of pH does not affect the potential reading or peak heights of the electrode in the range of 4.00-7.50 in batch condition. While in FIA, the peak heights representing the pH are almost stable in the range 4.00-6.00. The electrode is highly selective towards many inorganic cations, and neutral molecules. The obtained results indi...
New plastic membrane electrodes for amitriptyline hydrochloride (AmCl) based on amitriptylinium phosphotungstate (Am-PTA); amitriptylinium phosphomolybdate (Am-PMA) and a mixture of both (Am-PTA/PMA) were prepared. The electrodes were... more
New plastic membrane electrodes for amitriptyline hydrochloride (AmCl) based on amitriptylinium phosphotungstate (Am-PTA); amitriptylinium phosphomolybdate (Am-PMA) and a mixture of both (Am-PTA/PMA) were prepared. The electrodes were fully characterized in terms of their composition, life span, pH and temperature and then were applied to the potentiometric determination of the amitriptylinium ion in its pure state and pharmaceutical preparations and flow injection conditions. The selectivity of the electrodes towards many inorganic cations, sugars and amino acids was also tested.
Conductimetric determination of the antidepressants amitriptyline and dothiepin hydrochlorides and tranylcypromine hemisulphate in their pharmaceutical formulations Summary Simple and sensitive conductimetric methods for the determination... more
Conductimetric determination of the antidepressants amitriptyline and dothiepin hydrochlorides and tranylcypromine hemisulphate in their pharmaceutical formulations Summary Simple and sensitive conductimetric methods for the determination of amitriptyline hydrochloride, dothiepin hydrochloride and tranylcypromine hemisulphate are presented based on their ion associates with phosphotungstic and phosphomolybdic acids. The effects of solvent, molar ratio, reagent concentration and temperature were studied, and the solubility products of the formed ion associates were calculated. The method was applied to the determination of the drugs in pure state and their pharmaceutical preparations with mean recovery values of 96.25-104.90, 95.75-103.12 and 97.90-102.30%, and coefficients of variation of 0.23-1.62, 0.22-0.63 and 0.25-1.35 for amitriptyline, dothiepin hydrochlorides and tranylcypromine hemisulphate, respectively. The mean recovery values were 97.28-101.77, 97.60-104.50, 102.30-104.5...
The construction and performance characteristics of selegiline (Sel) carbon paste (CPEs) and plastic membranes electrodes are described. The cited electrodes are based on the ion associates selegiline phosphomolybdate (Sel-PMA) or... more
The construction and performance characteristics of selegiline (Sel) carbon paste (CPEs) and plastic membranes electrodes are described. The cited electrodes are based on the ion associates selegiline phosphomolybdate (Sel-PMA) or phosphotungstate (Sel-PTA). Matrix composition of each electrode is optimized on the basis of effects of type and concentration of the ionophore as well as influence of the selected plasticizers. Carbon nanotubes (CNTs) have a good conductivity which helps the transduction of the signal in carbon paste electrode, so the addition small quantity of multi-wall carbon nanotubes (MWCNTs) particles to the composition of carbon paste electrode gave a better performance characteristics for Sel-electrodes with Nernstion slope of 59.50 and 58.20 mV at 25C for Sel-PMA and Sel-PTA ion associates, respectively within a linear concentration range from 1.0x10 −5
This work demonstrates a facile electropolymerization of a dl-methionine (dl-met) conducting polymeric film on a gold nanoparticle (AuNPs)-modified glassy carbon electrode (GCE). The resulting sensor was successfully applied for the... more
This work demonstrates a facile electropolymerization of a dl-methionine (dl-met) conducting polymeric film on a gold nanoparticle (AuNPs)-modified glassy carbon electrode (GCE). The resulting sensor was successfully applied for the sensitive detection of paroxetine·HCl (PRX), a selective serotonin (5-HT) reuptake inhibitor (SSRIs), in its pharmaceutical formulations. The sensor was characterized morphologically using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) and electrochemical techniques such as differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The proposed sensor, poly (dl-met)/AuNPs-GCE, exhibited a linear response range from 5 × 10−11 to 5 × 10−8 M and from 5 × 10−8 to 1 × 10−4 M using DPV with lowest limit of detection (LOD = 1 × 10−11 M) based on (S/N = 3). The poly (dl-met)/AuNPs-GCE sensor was successfully applied for PRX determination in ...
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The increase of the global population and shortage of renewable water resources urges the development of possible remedies to improve the quality and reusability of waste and contaminated water supplies. Different water pollutants, such... more
The increase of the global population and shortage of renewable water resources urges the development of possible remedies to improve the quality and reusability of waste and contaminated water supplies. Different water pollutants, such as heavy metals, dyes, pesticides, endocrine disrupting compounds (EDCs), and pharmaceuticals, are produced through continuous technical and industrial developments that are emerging with the increasing population. Molecularly imprinted polymers (MIPs) represent a class of synthetic receptors that can be produced from different types of polymerization reactions between a target template and functional monomer(s), having functional groups specifically interacting with the template; such interactions can be tailored according to the purpose of designing the polymer and based on the nature of the target compounds. The removal of the template using suitable knocking out agents renders a recognition cavity that can specifically rebind to the target templa...