Cyclic Voltammetry Techniques Research Articles

Improved MnO2 based electrode performance arising from step by step heat treatment during electrodeposition of MnO2 for determination of paracetamol, 4-aminophenol, and 4-nitrophenol

The design of electrochemical sensors is crucial considering important factors such as efficiency, low cost, biocompatibility, and availability. Manganese oxides are readily available, low-cost, and biocompatible materials, but their low conductivity limits their efficiency as sensors. Today, morphology engineering of manganese oxide has been one of the most common research topics, because manganese oxides’ electrochemical properties are highly dependent on their morphologies. In this study, a method for reducing the charge transfer resistance (Rct) of MnO2-based electrodes was established by the cyclic voltammetry technique accompanied by step-by-step heat treatment to electrodeposition MnO2 nanofilm, which remarkably improved the Rct. Next, the sensing performance of MnO2/FTO for two separate measurements was examined, one for the simultaneous measurement of paracetamol (PAR) and 4-aminophenol (4-APh), and the other for the measurement of 4-nitrophenol (4-NP). Under the optimum conditions, the linear ranges of 4-APh, PAR, and 4-NP, were 0.8 to 22.0 µM, 2.0 to 55.0 µM, and 0.1–250 µM, with limits of detection (LOD) of 0.19 µM, 0.60 µM, and 0.01 µM, respectively. It also was unaffected by a 200-fold excess of interferences. In addition, the designed sensor was successfully applied to the analysis of real samples.

Fabrication of an electrochemical sensor based on Zinc Vanadate anchored with multi-walled carbon nanotubes modified glassy carbon electrode for the determination of Carbendazim

The detection of Carbendazim (CBZ) insecticides has prompted concerns regarding their potential impacts on both human health and the environment. To address this issue, a novel nanocomposite comprising Zinc Vanadate (ZVO) was prepared using a common hydrothermal technique and incorporated with multi-walled carbon nanotube (MWCNT) to form ZVO/MWCNT nanocomposite. Thus, a glassy carbon electrode (GCE) has been modified using this ZVO/MWCNT nanocomposite, which offering a simple and affordable platform for the electrochemcial detection of CBZ. The structure and composition of the nanomaterial were confirmed through various microscopic and spectroscopic techniques, while its electrochemical characteristics were investigated using electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and cyclic voltammetry (CV) techniques. The GCE/ZVO/MWCNT modified electrode exhibited a broad linear response ranging from 0.05 to 110μM, with a low detection limit of 0.005μM and high sensitivity (2.93 μA μM−1 cm−2), with recoveries ranging from 98% to 99.93%, respectively. Moreover, GCE/ZVO/MWCNT electrode demonstrated excellent stability, repeatability, and practical utility for CBZ detection. Based on electrochemical studies that indicate the formation of oxidized products consistent with a 2-electron transfer process. Therefore, this innovative GCE/ZVO/MWCNT modified electrode offers promising prospects for sensitive and selective CBZ determination, with potential applications in environmental monitoring and health protection.

Construction of calcium zirconate nanoparticles confined on graphitic carbon nitride: An electrochemical detection of diethofencarb in food samples

A well-known fungicide designated diethofencarb (DFC) is used on crops to eradicate fungal infections and increase agricultural production. However, the National Food Safety Standard has established an overall maximum residual limit of 1 mg/kg for DFC, and excessive usage of this chemical has detrimental effects on the environment in real-time. In this work, an improved electrochemical sensor based on hydrothermally synthesized CaZrO3 is incorporated into a g-C3N4 sheet and developed to quickly and accurately screen DFC, a well-known carbamate fungicide. The electrochemical sensor that was successfully designed demonstrated good conductivity, high ion diffusion parameters, a high electro-active surface area, and a quick electron transport ratio when used for DFC detection. The structure, crystalline accuracy, and purity of the as-prepared CaZrO3@g-C3N4 were examined using various analytical and microscopic techniques. Additionally, the cyclic voltammetry technique examined the electrochemical investigations of the CaZrO3@g-C3N4 modified glassy carbon electrode (GCE). A robust synergistic interaction between the CaZrO3 and g-C3N4 makes large surface areas and improved DFC detection possible. The fabricated sensor exhibits a wide linear range of 0.01–230.04 μM, a low detection limit of 1.8 nM, and excellent stability according to the results of the DPV technique. Remarkably, our proposed sensor has proven to be feasible for real-time analysis and can distinguish DFC-spiked various food samples with a good recovery range.

Fabrication of a molecularly imprinted poly(methyl methacrylate) decorated graphite electrode for detection of aloe emodin in Aloe vera

In this work, the authors represent a comprehensive approach for the development and validation of a novel graphite-supported molecularly imprinted poly(methyl methacrylate) electrode for the selective and sensitive detection of aloe emodin (AE) in aloe-based cosmetic products. The electrocatalytic activity of the electrode was evaluated using cyclic voltammetry and differential pulse voltammetry techniques in phosphate buffer saline. Surface morphology, structural characteristics, and imprinting endorsement were investigated using field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and UV-Vis spectroscopy. Under the optimal conditions, the electrode showed an oxidative differential pulse voltammetry peak at -0.2931±0.011 V (vs. Ag/AgCl, saturated KCl). The current was increased linearly with increasing concentrations of AE from 0.0005 to 350 µM, with a low detection limit of 0.0003 µM. The voltammetric analysis has been validated by reverse-phase high-performance liquid chromatography (RP-HPLC) methods. A partial least square regression model was developed to correlate the results obtained from the proposed system with the reference values obtained by RP-HPLC. The model showed a high prediction accuracy of 95.95 % for the detection of AE in cosmetic samples. The developed electrode provides a low-cost, rapid, easy, and convenient method for the detection of AE in cosmetic products, offering potential benefits for quality control and safety assessment in the cosmetic industry.

Poly(o-anisidine) and poly(o-anisidine-co-aniline) polymers synthesized on the ZnFeNi alloy coated steel surface

Abstract ZnFeNi alloy was synthesized on the carbon steel surface in a sulfate bath using the galvanostatic method at a constant current of 1.5 mA for 300 seconds. Poly(o-anisidine) homopolymer and poly(o-anisidine-co-aniline) copolymer were synthesized on the ZnFeNi coated electrode surface. Poly(o-anisidine) homopolymer was synthesized in 0.05 M o-anisidine+0.2 M sodium oxalate medium, and poly(o-anisidine-co-aniline) copolymer was synthesized in 0.05 M o-anisidine+0.05 M aniline+0.2 M sodium oxalate medium. Electrochemical synthesis was carried out by cyclic voltammetry technique. The synthesized materials were characterized by electrochemical impedance spectroscopy, linear sweep voltammetry, open circuit potential-time and anodic polarization curves. Open circuit potential-time curves showed that polymer coatings had higher open circuit potential. By linear sweep voltammetry measurements, it was determined that ZnFeNi alloys were present at the base of the polymer layers after polymer synthesis. It was understood from the anodic polarization curves that the polymer coated electrodes had lower current values ​​than the uncoated ZnFeNi coated electrode, and the poly(o-anisidine) coated electrode had lower current values ​​than the poly(o-anisidine-co-aniline) coated electrode. From electrochemical impedance spectroscopy measurements, it was determined that the polarization resistance of polymer-coated electrodes was higher than the polymer-free electrode during long periods of waiting in 3.5% corrosive solution. Among the polymer-coated electrodes, it was understood that the homopolymer poly(o-anisidine) showed better corrosion performance than the poly(o-anisidine-co-aniline) copolymer.

In situ and one-step electrodeposition growth of PtNi alloys on Ni foam for electrochemical ammonia-nitrogen sensing

The presence of ammonia-nitrogen in aquatic ecosystems has recently been recognized as a significant threat to public and ecological health. Hence, it is crucial to develop a reliable method for accurately quantifying low levels of this pollutant in the aquatic environment. In this work, PtNi alloys of varying compositions were fabricated via a one-step in-situ electrodeposition process on a Ni foam surface. The electrochemical catalytic performances for the ammonia oxidation reaction have been measured via the cyclic voltammetry (CV) technique. The experimental results demonstrated that the PtNi alloy exhibited the highest catalytic capability with the current density of 21.387 mA cm−2 for the ammonia oxidation reaction, when the ratio of H2PtCl6·6 H2O and Ni(NO3)2·6 H2O was 3:1 with the deposition time of 1500 s. Under the most favorable conditions, the electrochemical detection performance of the PtNi alloy in detecting ammonia-nitrogen has been extensively assessed based on the differential pulse voltammetry (DPV) technique. The experiments confirmed that the PtNi alloy demonstrated an outstanding sensitivity, reaching a remarkable value of 0.0255 mA µM−1, with a broad linear range from 3 µM to 500 µM. The PtNi alloy also demonstrated a remarkable low limit detection of 0.89 µM. In addition, Further evaluation of the anti-interference ability, reproducibility, stability and recovery in real sample analysis including tap water, lake water and sea water revealed that the PtNi alloy exhibited superior performance for detecting ammonia-nitrogen.

Fabrication of ultra-sensitive and disposable electrochemical biosensor: Detection of kidney injury molecule-1 protein in urine for diagnosis of kidney injury

This research study indicates the development of the indium tin oxide-polyethylene terephthalate (ITO-PET) coated electrode-based electrochemical biosensor system to sensitively and specifically detect kidney injury molecule-1 (KIM-1), an acute kidney injury (AKI) biomarker. The ITO-PET electrode surface was modified with 3-(Trimethoxysilyl)-1-propanethiol (3-TMESP) silane agent. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and single frequency impedance (SFI) techniques were utilized to examine the interactions between anti-KIM-1 antibody and KIM-1 antigen. The ITO-PET electrode surface was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to analyze the morphological characterization at each electrode development stage. Optimization studies have been conducted to determine the optimal concentrations for detecting the 3-TMESP silane agent, the NHS crosslinker, the anti-KIM-1 antibody, and the optimum incubation period for the anti-KIM-1 antibody and the KIM-1 antigen. Analytical characteristic properties of the developed biosensor, including linear determination range, and the studies of reproducibility, regeneration, repeatability, storage life, and selectivity were investigated. The KIM-1 biosensor system, based on 3-TMESP, has a broad linear range and is capable of providing sensitive measurements between 0.1 fg/mL and 1000 fg/mL. The values of low limits of detection (0.26 fg/mL) and of quantification (0.87 fg/mL) were calculated, highlighting its high sensitivity and precision in detecting KIM-1. In addition, five different commercially purchased human urine samples were tested to validate the practicability of the developed biosensor.

Electro‐Oxidation of Ibuprofen and Metoprolol Using a Manganese Oxide Platform

AbstractPharmaceutical compounds, such as ibuprofen and metoprolol, are of increasing concern due to their persistence in the environment and potential adverse effects on human health. In this work, we developed an electrochemical sensor system for the determination of ibuprofen and metoprolol based on a modified manganese oxide nanoparticle (MnO2NPs) on a screen‐printed carbon electrode (SPCE). The characterisation of MnO2NPs modifier was investigated via Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy techniques, Uv/vis spectroscopy, and small‐angle X‐ray scattering spectroscopy. The electrochemical behaviour of the MnO2NPs was studied using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. The optimum experimental conditions were investigated by examining the effects of scan rates, pH on the CV responses, and electrolytes on the DPV response. The MnO2NPs modified electrode demonstrated enhanced catalytic activity in the electro‐oxidation of both ibuprofen and metoprolol. The oxidation peaks of ibuprofen and metoprolol were observed at +1.14 V and +1.46 V, respectively, for the MnO2NPs/SPCE sensor. The sensor's limit of detection was 3.81 pM and 4.6 pM respectively and its linear response was from 0.97–5.82 pM. Furthermore, interference and stability studies were conducted to evaluate the performance of the MnO2NPs/SPCE sensor under optimum conditions, which resulted in a good performance. The proposed sensor was successfully used for the determination of ibuprofen and metoprolol in the application of real water samples.

Mechanistic Insights into the Potentiodynamic Electrosynthesis of PEDOT Thin Films at a Polarizable Liquid|Liquid Interface.

Conducting polymer (CP) thin films find widespread use, for example in bioelectronic, energy harvesting and storage, and drug delivery technology. Electrosynthesis at a polarizable liquid|liquid interface using an aqueous oxidant and organic soluble monomer provides a route to free-standing and scalable CP thin films, such as poly(3,4-ethylenedioxythiophene) (PEDOT), in a single step at ambient conditions. Here, using the potentiodynamic technique of cyclic voltammetry, interfacial electrosynthesis involving ion exchange, electron transfer, and proton adsorption charge transfer processes is shown to be mechanistically distinct from CP electropolymerization at a solid electrode|electrolyte interface. During interfacial electrosynthesis, the applied interfacial Galvani potential difference controls the interfacial concentration of the oxidant, but not the CP redox state. Nevertheless, typical CP electropolymerization electrochemical behaviors, such as steady charge accumulation with each successive cycle and the appearance of a nucleation loop, were observed. By combining (spectro)electrochemical measurements and theoretical models, this work identifies the underlying mechanistic origin of each feature on the cyclic voltammograms (CVs) due to charge accumulated from Faradaic and capacitive processes as the PEDOT thin film grows. To prevent overoxidation during interfacial electrosynthesis with a powerful cerium aqueous oxidant, scan rates in excess 25 mV·s-1 were optimal. The experimental methodology and theoretical models outlined in this article provide a broadly generic framework to understand evolving CVs during interfacial electrosynthesis using any suitable oxidant/monomer combination.

Enzymeless Gabapentin Sensor Based on Prussian Blue-modified Indium Tin Oxide Electrodes for Sensing Gabapentin in Capsules

Background: In this study, we reported on developing a susceptible, accurate, simple, and economical electrochemical sensor for gabapentin determination in capsules. Methods: The ITO electrode was modified with a layer of Prussian blue nanoparticles and then used as the working electrode. Gabapentin was extracted from commercial capsules, and a series of concentrations of gabapentin were prepared for studying the efficacy of the proposed sensor. The electrochemical measurements were performed using cyclic voltammetry and square wave voltammetry techniques. Results: The sensitivity and selectivity of the developed electrode toward gabapentin in different interferences, including citric acid, glucose, and urea, were investigated. The modified electrode showed detection and quantification limits of 31.58 and 94.74 nM, respectively, over a dynamic range of concentrations from 100 nM to 3 μM. Conclusion: The proposed sensor displayed a high sensitivity and selectivity for monitoring gabapentin in pharmaceutical drugs without a noticeable interference. Hence, the modified electrodes are great candidates for gabapentin routine analysis.

Bio-derived gel polymer electrolytes from zein and honey blends integrated with ammonium nitrate for electrical double layer capacitors

Although electrical double layer capacitors (EDLCs) are known to exhibit impressive power density, rapid charging/discharging, and long cycle life, their energy density remains a hurdle for broader use. Gel polymer electrolytes (GPEs) offer an interesting approach to improve the energy density of EDLCs while maintaining their other desirable characteristics. This study investigates the development of novel GPEs based on zein, honey, and ammonium nitrate (NH4NO3) for EDLC applications. The GPEs are prepared by incorporating zein, honey, and NH4NO3 in a dimethyl sulfoxide (DMSO) solvent system through a solution casting method. The degree of crystallinity of zein successfully reduced from 33.0 % to 15.71 % with the addition of 20 wt% NH4NO3. The interaction between zein, honey and NH4NO3 is confirmed by observing the shifting of the hydroxyl band. The ambient ionic conductivity of zein-honey increases from (4.86 ± 0.36) × 10−4 S cm−1 to (4.19 ± 0.40) × 10−3 S cm−1 with the incorporation of 20 wt% NH4NO3 (ZH20), exhibiting the significantly lowest Tg value (77.53 °C). Linear sweep voltammetry (LSV) demonstrates high electrochemical stability up to 2.6 V of ZH20. Additionally, the transference number (tion) of 0.989 indicates a dominant role of ionic charge carriers in this work. Finally, the ZH20-based GPE is used as both an electrolyte and separator to fabricate EDLC. Its electrochemical behavior has demonstrated stable results in terms of specific capacitance, energy, and power density, with fast rate performance observed through cyclic voltammetry and galvanostatic charge-discharge techniques.

Antioxidant Activity of Gold Nanofilms Synthesized via Cyclic Voltammetry Technique

Abstract Gold nanoparticles (AuNPs) have attracted much attention as one of the most effective agents with high catalytic activities for radical scavenging reactions. Many studies have investigated its antioxidant activity using various in vitro methods and have shown promising scavenging action. In this research, we demonstrated the synthesis of Au nanofilms (AuNFs) by cyclic voltammetry technique and evaluated for their antioxidant activity. The application of a range of voltage levels was utilized in the synthesis of AuNFs, and their antioxidant potential was subsequently assessed through in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. All AuNFs exhibited antioxidant activity which increased as the upper potential was reduced from 1,5 V to 0,75 V. The antioxidant activity of AuNFs was shown to increase gradually with longer incubation times before the DPPH assay, indicating a significant impact on their performance. The obtained inhibition percentage was ranging from 8,26% to 22,91%. The highest antioxidant activity could be achieved by synthesizing AuNFs using 0,75V of upper potential and incubating it for 90 minutes prior to DPPH assay. The variations in the applied potential influenced the morphological characteristics of AuNFs, leading to increased surface area, while the duration of incubation was found to enhance the efficacy of the scavenging reaction between the AuNFs and DPPH. In conclusion, this cyclic voltammetry technique was shown to successfully synthesize AuNFs with significant antioxidant activity.

Sustainable Synthesis of Novel Calcium Magnesium Nanoferrites for Biomolecules Sensing and its Antimicrobial Properties

AbstractSustainable synthesis of novel Calcium magnesium ferrite nanomaterial was carried out in this work using aloe vera plant extract as a fuel for the combustion method. Structural characterizations of the synthesized material shows the crystallite size∼ 14 nm with cubic structure and chemical bonds between Ca−O and Fe−O. Porous nature and agglomerated particles were observed in morphological analysis. Modified carbon paste, glassy carbon and screen printed electrodes were prepared using the synthesized nanomaterial for biomolecules sensing using cyclic voltammetry technique. Therefore, the present green synthesized CMF nanoparticles modified carbon paste electrode shows significantly high sensitivity and hence it can be used as a sensor for biomedical application. Employing the agar disc diffusion technique, the antimicrobial activity of the synthesized nanoparticles was ascertained. C against the pathogens like Pseudomonas spp., E coli, and Staphylococcus spp.

Sensitive Electrochemical Sensing Properties for Cyanide Detection Using Polyaniline/Cu-Vanadate Nanobelt-modified Electrode

Background: Cyanide is a toxic anion and may be discarded into the water environment, which is a serious threat to human beings and the environment. Hence, it is essential to explore a facile, sensitive method for cyanide detection. Polyaniline/Cu vanadate nanobelts serve as electrode materials for sensitive cyanide determination. Methods: Polyaniline/Cu vanadate nanobelts were obtained by a simple route using polyaniline, Cu vanadate nanobelts. The polyaniline/Cu vanadate nanobelts were measured via electron microscopy, diffraction, infrared spectrum, and electrochemical methods. Results: Amorphous polyaniline nanoparticles with a particle size of about 100 nm were attached firmly to the surface of Cu vanadate nanobelts. Electrochemical sensing properties for cyanide detection were analyzed using a cyclic voltammetry technique using the nanobelts-modified electrode. The cyclic voltammograms (CV) peaks centered at +0.64 V and +0.54 V were observed using the polyaniline/Cu vanadate nanobelts in 0.1 M KCl solution with 2 mM cyanide. The proposed composite nanobelt-modified electrode possessed the detection range and detection limit of 0.001-2 mM and 0.22 μM, respectively. Conclusion: Polyaniline greatly enhances the electro-catalytic performance of the Cu vanadate nanobelt-modified electrode for cyanide detection.

Comprehensive investigation of zinc and tin-based metal oxides for advanced electrochemical detection of organophosphate pesticides

Different metal oxide (MO) nanomaterials, such as ZnO, SnO2, and nanocomposites of ZnO:SnO2 with various ratios of (1:9), (2:8), and (3:7) were prepared and coated on glassy carbon electrode (GCE). These MOs were tested as sensing material for organophosphate (OP) pesticides detection. Among all MOs, ZnO:SnO2 (1:9) coated GCE increases redox peak current at different buffer solutions with varying pH compared to bare GCE. Moreover, among these pH values, ZnO:SnO2 (1:9) coated GCE significantly enhanced the redox peak at pH 6.2, emphasizing optimal electrochemical conditions for the given pesticides. The morphological, elemental composition, metal ions-functional group interation, and crystallinity of different MO nanocomposites were examined using field-emission scanning electron microscopy (FESEM), fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectrum (EDX), and X-ray diffraction (XRD), respectively. The modified GCE with ZnO:SnO2 (1:9) showed an excellent performance during the electrochemial sensing of the diazinon (DiZn) pesticide. Therefore, detailed study was carried out for the sensing of DiZn. Furthermore, the electrochemical behavior of the ZnO:SnO2 (1:9) coated GCE was evaluated using cyclic voltammetry (CV) with 0.5 mL (5 mM) potassium ferrocyanide, resulting in a pronounced increase in anodic and cathodic peak potentials (Epa = 0.423 V, Epc = 0.1945 V) and currents (Ipa = 9.867 × 10-5 mA, Ipc = -7.993 × 10-5 mA). In addition, electrochemical impedance spectroscopy (EIS) demonstrated a reduction in charge transfer resistance for the coated ZnO:SnO2 (1:9) GCE. Differential pulse voltammetry (DPV) further showed a linear relationship between current and pesticide concentration, with a high correlation coefficient (R2 = 0.996), low limit of detection (LOD = 0.0133 mM) and low limit of quantification (LOQ = 0.0405 mM). Real samples, including tap and seawater, were analyzed to validate the method’s applicability. Additionally, chronoamperometry with a step potential of 1.2 V indicated high sensitivity for DiZn detection, with a sensitivity of 0.23 mA mM−1 cm−2. Finally, the stability of the ZnO:SnO2 (1:9) coated GCE was confirmed through recyclability tests over three cycles using CV and DPV techniques, ensuring its robustness for practical applications in pesticide detection.

Green Voltammetric Detection of Ophthalmic Drug Nepafenac Using Pencil Graphite Electrode as a Responsive Disposable Electrochemical Sensor

AbstractIn this study, the electrochemical properties of nepafenac, used after eye surgery operations, were investigated on a disposable pencil graphite electrode. Cyclic and square wave voltammetry techniques were used to investigate the electrochemical properties of nepafenac. Two peaks at potentials of approximately +0.33 V and +1.03 V in the anodic direction and two peaks at potentials of approximately +0.29 V and +0.08 V in the cathodic direction were observed on the surface of the disposable pencil electrode in acetate (pH 4.8) medium with the cyclic voltammetry technique. The analytical performance of the developed voltammetric technique had good linearity in the concentration range of 0.30 µM to 3.5 µM at pH 4.8. The LOD value of this voltammetric method in acetate (pH 4.8) medium was calculated as 0.035 µM (8.90 ng mL−1). For reproducibility, the relative standard deviation (RSD) values for Ia and IIa anodic peak current/potential were found to be 1.45%/0.43% and 1.28%/0.25%, respectively. The voltammetric method was successfully applied to urine and pharmaceutical preparations and the results were compared with the spectrophotometric method.

Highly sensitive electrochemical sensor based on flexible porous graphene for cortisol detection

This report presents the development of an electrochemical sensor for detecting cortisol in sweat, utilizing a flexible porous graphene electrode (fPGE). The fPGE was created using the laser-induced graphene technique on a polyimide substrate. The characterization of the porous graphene material was conducted through SEM and Raman spectroscopy. The graphene surface of the fPGE was modified with cortisol-aptamer with the assistance of linker molecules, PASE, to form the cortisol sensor. The electrochemical properties of the sensor were assessed using cyclic voltammetry technique (CV). Cortisol detection in the sensor was achieved indirectly via the reaction of the redox couple K4[Fe(CN)6]/K3[Fe(CN)6] on the surface of the cortisol aptamer-modified fPGE. As the concentration of cortisol in the solution increased, the corresponding current in the CV decreased. Under optimized conditions, the electrochemical cortisol sensor demonstrated a wide dynamic range of cortisol concentration from femtomolar (fM) to micromolar (µM) with a low limit of detection (LOD) of 100 fM.

Preparation Of Modified Surfaces Based On Tannic Acid and Carbon Nanotubes and Investigation Of Their Electrochemical Properties

This study focuses on the electrochemical investigation of modifiers and their components that can provide the easiest and most sensitive results for electrochemical sensors. For this purpose, a nanocomposite of tannic acid and carbon nanotubes with extraordinary properties was obtained. The nanocomposite and its components were immobilized on glassy carbon electrode surfaces by the drop-drying technique. The morphological and electrochemical properties of the nanocomposite and its components were examined by scanning electron microscopy and cyclic voltammetry techniques. The surfaces modified with the nanocomposite and its components exhibited different electrochemical behaviors. Tests performed in ferricyanide, ferrocene, ruthenium hexamine (III) chloride, and ferricyanide/ferrocyanide probes showed that the nanocomposite-modified surface exhibited the best voltammetric behavior. Scan rate and pH studies showed that the nanocomposite-modified surface catalyzed electron transfer more and increased the active surface area.

Creative synthesis of pH-dependent nanoporous pectic acid grafted with acrylamide and acrylic acid copolymer as an ultrasensitive and selective riboflavin electrochemical sensor in real samples

In current research, an innovative pectic acid was grafted with poly (acrylamide-co-acrylic acid) [PA-g-poly (AAm-co-AA)] nanoporous membrane using a free radical-mediated grafting copolymerization process. The optimized parameters for the grafting copolymerization reaction such as initiator concentration, monomer concentrations, polymerization reaction time, and temperature were studied. Additionally, the solid content, graft percentage, and conversion were calculated. The unique polymeric membrane was characterized using Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetry (TG), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) supported by energy dispersive X-ray spectroscopy (EDX). The formulated novel PA-g-poly (AAm-co-AA) had a nanoporous structure with a diameter of 113 nm. pH-dependent swelling and biodegradation measurements were also studied. The electrochemical characterizations of PA-g-poly (AAm-co-AA) were conducted through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Furthermore, the screen-printed electrode (SPE) was modified with pure PA and the new generation of its grafted polymeric nanoparticles to detect and quantify the concentration of riboflavin (RF) in real samples using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified electrode showed two linear concentration ranges from 0.01 - 2 nM and 2 – 90 nM with low detection limits (LODs) of 0.004 and 0.97 nM, respectively, demonstrating high sensitivity. Besides, the fabricated sensor exhibited more selectivity, simplicity, great reproducibility, repeatability, and good stability. Finally, the PA-g-poly (AAm-co-AA)-modified SPE based sensor was effectively used in real sample analysis of egg yolk, milk, and vitamin B2 drugs with good recovery rates.

Microfluidic Reservoir Integrated with Optimized Screen-Printed Electrode for Simultaneous Detection of Ascorbic Acid and L-Cysteine

Abstract iomarker detection is crucial in the healthcare industry as it gives important insights into the field of disease diagnosis, prognosis, and treatment. This work demonstrates a flexible carbon-based screen-printed electrode (CSPE) modified with carboxylic acid functionalized multiwalled carbon nanotube (MWCNT-COOH) for simultaneous detection of Ascorbic acid (AA) and L-Cysteine (CySH). The electrochemical properties of the fabricated film are studied using the Cyclic voltammetry (CV) and Amperometry technique. The MWCNT-COOH/CSPE showed good electrocatalytic activity for oxidation of CySH and AA. Favorable ionic interaction, or electrostatic attraction, between the analytes and MWCNT-COOH increased the detection capability. The fabricated electrode is incorporated with a microfluidic reservoir to hold the analyte that can separately detect AA and CySH using the device. The device is tested for a linear range of 0.01 mM to 20 mM for both analytes. The detection limit for AA and CySH obtained using amperometry analysis is 3.07 µM and 5.72 µM, respectively. Also, the calculated quantification limits values are 9.11 µM and 17.3 µM, respectively for AA and CySH. Further, the device demonstrates appreciable results in both real sample analysis and interference analysis. The device, enabled with screen printed electrodes and microfluidic reservoir, opens a new method for simultaneous multiplexed detection enabling the detection of many different biomarkers on the same experimental setup.