GCE Surface Research Articles

ZIF-12-derived nitrogen doped porous carbon nanosheets-functionalized with silver nanoparticles for ratiometric molecularly-imprinted electrochemical sensing of D-penicillamine

In this work, an electrochemical platform was developed for detection of D-pencillamine utilizing highly responsive molecularly imprinted polymers (MIPs). This platform operates on a ratiometric principle and is constructed on nitrogen-doped porous carbon nanosheets (N-PCNS) derived from zeolite imidazolate frameworks (ZIF-12) in the presence of saturated solution of zinc sulfate. Subsequently, silver nanoparticles (Ag) were introduced onto the surface of N-PCNS/GCE to enhance conductivity and surface area, and serve as a standard signal. The MIP layer was formed on the Ag@N-PCNS/GCE surface through o-phenylenediamine (o-phen) electro-polymerization in the presence of the D-pencillamine (D-PAN) as a template. Detection of D-PAN relies on measuring ID-PAN/IAg response ratio employing differential pulse voltammetry (DPV). This ratio exhibits a linear correlation with the concentration of D-PAN in the dynamic linear range of 0.161–170 µM, exploiting LOD of 38.0 nM (S/N = 3). The electrochemical sensor offers numerous advantages including low detection limit, accuracy, stability, and sufficient degree of selectivity. Utilizing this platform, D-PAN-containing samples were efficiently analyzed with recovery percentages of 98.0–102.0 % and RSDs of 2.78–3.89 %, demonstrating the accuracy of the method.

Two one‐dimensional cuprous iodide coordination polymers: Efficient and robust electrocatalysts for hydrogen evolution and glucose‐sensing

Development of efficient, low‐cost, robust, and structure tunability electrocatalysts for hydrogen evolution reaction (HER) is one of the main subjects of present study in renewable energies. In this work, two new cuprous iodide coordination polymers (Cu‐CPs) containing bisbenzimidazole‐derived ligand, namely, {[Cu2(L1)(μ2‐I)2]·DMF}n (1) and {[Cu(L2)0.5(μ2‐I)]·DMF} (2) (L1 = (2,2′‐(1,3‐propanediyl)‐6,6′‐bis(3‐methylpyridine)bis‐1,3‐benzimidazole); L2 = (2,2′‐(1,4‐butanediyl)‐7,7′‐bis(3‐methylpyridine)bis‐1,3‐benzimidazole); DMF = dimethyl formamide), were prepared under solvothermal conditions and structurally characterized. Single‐crystal structural analysis showed that although two Cu‐CPs have a one‐dimensional (1D) chain backbone structure, the coordination environment of cuprous is different. It is found that different coordination modes of ligands L1 and L2 lead to different coordination environments of central ions in two cuprous CPs. Electrocatalytic HER of modified electrodes (CP‐1~2/glassy carbon electrode [GCE]) prepared by coating the mixed solution of acetylene black, CPs 1–2, and Nafion on the surface of GCE was investigated in 0.5 M H2SO4 electrolyte. The HER measurements show that the overpotential η10293K of CP‐1~2/GCE positively shifted 113 and 74 mV compared with bare GCE (blank electrode, −930 mV), and the Tafel slope of bare/GCE and CP‐1~2/GCE were 298, 101, and 138 mV dec−1, respectively. The results indicate that CP‐1~2/GCE could effectively catalyze and accelerate the HER behavior, with electrocatalytic activity order being CP‐1/GCE > CP‐2/GCE > bare/GCE. The higher HER activity of the CP‐1/GCE can be attributed to that the coordination deformability of cuprous ion in CP 1 is greater. Furthermore, the recognition performance of CP‐1~2/GCE for glucose was further studied by chronoamperometry in 0.1 M NaOH. The two sensors can detect glucose in a linear range from 1 μM to 4 mM with sensitivities of 13.736 and 18.945 μA mM−1, and also revealed long‐term stability and good selectivity. These results indicate that cuprous CPs deserve further investigation as potential electrocatalyst candidates.

Facile synthesis of PEDOT@rGO nanocomposites for novel electrochemical sensor for the determination of 4-chlorophenol in a real water sample

A sensitive electrochemical sensor was developed for the detection of 4-chlorophenol (4-CP) using the nanocomposite based on poly (3,4-ethylenedioxythiophene) and reduced graphene oxide (PEDOT-rGO). The GC electrode modified with the proposed nanocomposite was characterized using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and electrochemical impedance spectroscopy. The Raman analysis confirmed the successful incorporation of PEDOT onto the reduced graphene oxide (rGO) surface. It is also observed in the SEM analysis that PEDOT nanoparticles were spread over the rGO sheet. The lower charge transfer resistance (Rct) values for PEDOT-rGO/GCE compared to PEDOT/GCE in electrochemical impedance spectroscopy confirms the unique conducting properties of rGO and the higher surface area of PEDOT in the proposed composite on the GCE surface. The cyclic voltammetric and differential pulse voltammetric (DPV) results has indicated that the PEDOT-rGO-modified glassy carbon electrode is an excellent electrocatalyst for the detection of 4-CP compared to PEDOT and rGO. This counterpart exhibited a good linear relationship in the range of 5–250 μM, with a detection limit of 12 nM in the DPV technique. This sensor was also employed for the determination of 4-CP in river water samples. The accuracy of the analytical electrochemical sensor for 4-CP was comparatively analyzed using the obtained UV–visible spectral data, indicating a detection limit of 21 nM. Hence, the electrochemical method was successfully employed to obtain a lower detection limit for 4-CP than that for electronic absorption spectral observations. All the observed results were consistent with our expectations and showed that this novel PEDOT-rGO/GCE has good repeatability and stability and without any impactable interference behavior.

Determination of imatinib as anticancer drug in serum and urine samples by electrochemical technique using a chitosan/graphene oxide modified electrode

The purpose of this work was to construct an electrochemical sensor for the detection of imatinib. It was based on a modified glassy carbon electrode (chitosan/rGO/GCE) that was a reduced graphene oxide nanocomposite. By employing a straightforward drop-casting technique, the rGO/chitosan composite was applied to the GCE surface. The XRD, FT-IR, and FE-SEM structural studies verified that graphene oxide was successfully reduced and that the rGO/chitosan nanocomposite was formed. The synergistic effect of rGO and chitosan boosted electron transfer kinetics and facilitated the oxidation reaction of imatinib on the electrode surface, according to electrochemical experiments, which indicated the chitosan/rGO/GCE's sensitive, selective, and stable response to imatinib. The findings showed sensitivity of 0.16502 μA/μM, detection limit value of 7.3 nM, and a wide and stable linear range of 1–300 µM. Differential pulse voltammetry measurements were performed on prepared human serum and urine samples to evaluate the applicability of chitosan/rGO/GCE for imatinib detection in real samples. For the prepared genuine samples, the chitosan/rGO/GCE showed good recoveries ranging from 95.00% to 99.20% with a relative standard deviation of 3.10–4.49%. These findings showed that imatinib in a variety of genuine samples may be accurately analyzed using the chitosan/rGO/GCE.

Non-enzymatic electrochemical sensing platform based on metal oxide-loaded biopolymer for voltammetric measurement of hepatoprotective metadoxine drug in pharmaceutical formulation and human blood serum

This study focuses on the first-ever high-sensitivity, low-cost, and quick response electrochemical estimation of metadoxine (MTD) in pharmaceuticals and human blood serum using a non-enzymatic nanocomposite modified glassy carbon electrode (CuO/CH/GCE) loaded with chitosan. The electroactive surface of GCE was produced by drop-casting a suspension of CuO/CH nanocomposite in N,N-dimethylformamide (DMF) onto the non-enzymatic electrode surface. Synthesized nanocomposite was characterised by using XRD, XPS, EDX, TEM, Raman and FESEM techniques. EIS technique was utilized to study the enhanced charge-transfer phenomenon occurring at the surface of modified sensor. The electrooxidation of MTD at CuO/CH/GCE surface is depending at pH of supporting electrolyte, scan rate and concentration of analyte. CV and SWV technique were used to carry out electrochemical study, optimised voltammetric response is observed in the BR buffer at pH 2.5, with irreversible diffusion-controlled process. Within the linear concentration range of MTD from 1.99 μg/L to 29.56 μg/L, this sensor exhibited lowest LOD (0.64 μg/L) and LOQ (2.14 μg/L). The MTD in pharmaceutical formulation and human blood serum can be determined with this highly selective peak potential (Ep ∼ 1.2 V), repeatable (%RSD 0.91), and reproducible (%RSD 2.31) method. The average percentage recovery in human blood serum and pharmaceutical formulation is 99.89% and 99.90%. This paper reports a lowest LOD value for MTD detection in the comparison with other reported methods (Table S1). None of the selected excipients were found to interfere more than 5% with redox potential of MTD without affecting the performance of sensor.

Subtle adjustment of the cyclic potential on electro-activated glassy carbon electrodes for sensitive sensing of methyl parathion.

Facile electro-activated glassy carbon electrodes (e-GCEs), which are prepared in electrolyte solution with a certain potential for a few seconds, have been verified to improve analytical performance toward not a few electro-active molecules recently. Nevertheless, how and why the potential plays an important role is not clear, and has even not received enough consideration. In this paper, we found that the mode and the range of applied potential significantly impacted the sensitivity of methyl parathion (MP), which is a typical pesticide with the electro-active group of -NO2. Compared with constant potential, the e-GCE with cyclic potential provided a much more stable baseline during MP detection. Additionally, the electro-oxidation peak current of MP at around -0.1 V on it was higher than another changeable potential (constant current). What's more interesting, with cyclic potential for 50 segments from -2 to 1.5 V, the peak current value increased by 30 times in comparison with a bare GCE, but only 2 times from -2 to 1 V. Then after systematic investigation including structures of the electrode surface and functional groups, we speculated that the produced group of O-CO in the process of activation and remaining groups of C-O and CO on the bare GCE surface are beneficial for adsorbing MP molecules leading to enhanced peak current. Employing the proposed e-GCE, the limit of detection of MP reached 0.015 μM and the reproducibility was perfect. This work elucidates the potent impact of electro-activation potential parameters on electroanalysis behaviors.

Real-time detection of sorafenib in human serum samples: An evaluation study via electrochemical sensing probe fabricated with silver stannate

BackgroundIn this present work we are aiming to develop an Ag2SnO3 based electrochemical sensor for the detection of kinase inhibitor sorafenib (SRF). The detection of such cancer drugs is important to monitor on the lab scale. The employed Ag2SnO3 with good electrical conductivity, catalytic activity, easier preparation method, earth-abundant nature, and noteworthy features make it more vital as electrode material for sensing SRF. MethodsThe Ag2SnO3 was prepared via hydrothermal method and then characterized with XRD, and XPS analysis to extend its structural presence better. The FESEM analysis was also studied to know the morphology of Ag2SnO3 with the elemental presence verified with EDAX and mapping analysis. The support of Ag2SnO3 over the GCE surface aided the study in better understanding the reaction kinetics with SRF at the electrode interface. The serum samples from patients with SRF intake for different time periods were collected and analyzed for electrochemical performances. Significant findingsThe electrochemical response as recorded provides the presence of SRF in serum samples in comparison with the non-intake of SRF. The SRF analysis studied with the DPV technique with a linear range of about 0.49 to 167.41 µM showed a good response at Ag2SnO3/GCE. Thus, the present study highlights the detection of SRF in human blood serum samples with a lower detection limit 0.043 µM and a good sensitivity of 0.988 μA μM−1 cm2. The presence of SRF was also identified and compared with the initial day of intake. The Ag2SnO3 with high surface area and high conductivity effectively improved the performance.

Signal Amplification for Detection of Nilutamide in Three-Dimensional Electrochemical Sensor Using Copper Metal–Organic Framework Decorated Carbon Nanofibers

The extensive use of antibiotics has rapidly spread antibiotic resistance, which poses significant health risks to humans. Unfortunately, despite this pressing issue, there is still a lack of a reliable on-site detection method for the residues of antibiotics, such as nilutamide (Nlu). Consequently, there is an urgent need to develop and perfect such a detection method to effectively monitor and control antibiotic residues. In this study, the hydrothermal development of copper-metal-organic framework (Cu-MOF) polyhedrons on the functionalized carbon nanofiber (f-CNF) matrix allowed for the detection of Nlu in biological liquids via a sensitive amperometry technique. Further electrochemical detection of Nlu took place with the cyclic voltammetry (CV) technique Cu-MOF/f-CNF. Analytical and spectroscopic approaches were used to confirm the successful synthesis of Cu-MOF/f-CNF. The prepared material was decorated on the surface of GCE and performed as an electrochemical Nlu sensor, with a broad linear range of 0.01 to 141.4 μM and 2 nM as a lower limit of detection. In addition, the composites had a large surface area and many dedicated sites, which improved electrocatalysis. In practical applications, Cu-MOF/f-CNF/GCE provides a novel strategy for improving electrochemical activity by measuring Nlu concentrations in biological samples.

Development of a high-performance label-free electrochemical immunosensor for early cancer diagnosis using anti-CEA/Ag-MOF/GO/GCE nanocomposite

In order to detect carcinoembryonic antigen (CEA) as a tumor marker in lung cancer for early cancer diagnosis, this study aimed to develop a label-free electrochemical immunosensor based on the immobilization of an Anti-CEA antibody on a metal-organic framework (MOF)-graphene oxide nanocomposite modified glassy carbon electrode (Anti-CEA/Ag-MOF/GO/GCE). Ag-MOF/GO nanocomposite was prepared on the GCE surface using the ultrasonic irradiation method, and Anti-CEA antibody was subsequently immobilized on the surface. Analysis of the crystal structure and morphology of the modified electrode using FE-SEM and XRD revealed that the correct combination of GO nanosheets and Ag-MOF nanoparticles produced a high surface area to trap the antibodies. Electrochemical tests utilizing the CV and DPV methods revealed that the immunosensor's sensitivity, stability, and selectivity were improved by Anti-CEA/Ag-MOF/GO/GCE. Results showed that, with a detection limit of 0.005 ng/mL, the change in the reduction peak current was inversely correlated with the logarithm concentration of CEA in the range of 10-3 to 5000 ng/mL. The suggested CEA immunosensor's applicability in a human serum sample was investigated, and findings of analytical studies via standard addition technique for both ELISA and DPV assays revealed that significant agreement existed between the outcomes of the two assays. Additionally, the recoveries ranged from 99.00% to 99.25%, and all relative standard deviations (RSDs) for the sample detections were below 5.01%, indicating satisfactory accuracy in results measured with the proposed CEA immunosensor, indicating that the prepared CEA immunosensor in this study can be used in clinical applications and human fluids.

Highly sensitive photoelectrochemical sensor based rGO/CuI-modified glassy carbon electrode for monitoring chloramphenicol

Carbon-nanomaterials-based photoelectrochemical sensors have received attention and become promising methods in analytical techniques due to their unique benefits, such as easy fabrication, high sensitivity, and selectivity. Herein, the rGO/CuI-modified glassy carbon electrode (rGO/CuI-GCE) has been fabricated to enhance the sensitivity detection of chloramphenicol (CAP). The rGO/CuI was synthesized using the co-precipitation method, while the rGO/CuI-GCE was fabricated using a dropping technique on the GCE surface. The properties of rGO/CuI were studied by x-ray diffraction (XRD), fourier transform infrared (FTIR), raman spectroscopy, UV–Vis spectroscopy, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Furthermore, using a three-standard electrode, the photoelectrochemistry of rGO/CuI-GCE was studied by observing the photocurrent response to time (i vs t). Under optimal conditions, the rGO/CuI-GCE sensor presented significant CAP detection performance in the 0–40 uM with a detection LOD of 8.6 nM (S/N = 3). The sensor also has good stability and selectivity. In addition, the developed sensor was successfully applied to detect CAP in fresh milk and urine with a good % recovery value. The developed photoelectrochemical sensor based on rGO/CuI-modified GCE offers a promising approach for enhancing the sensitivity detection of CAP and others.

Rational Construction of V2O5 with Functionalized MWCNTs: An Efficient Electron Transfer Electrode Material for Facile Detection of N-acetyl-p-aminophenol

N-acetyl-p-aminophenol, commonly known as paracetamol (PAL), is a widely prescribed drug for the treatment of fever and moderate pain. The presence of PAL at trace levels has been detected in hospital wastewater, drinking water, and sewage water, primarily due to its excretion from human and animal urine. Therefore, this work intends to improve the detection of PAL in human urine, thereby boosting its monitoring and analysis in environmental samples. Here in we developed a rational construction of the nanoflake structured vanadium pentoxide (V2O5) particles with functionalized multiwalled carbon nanotube [V2O5@f-MWCNT (1–4)] and evaluated their electrocatalytic performance for the detection of PAL. The synthesized materials were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Field emission scanning electron microscopy (FE-SEM) with elemental mapping analysis. The electrocatalytic performance of different electrocatalysts on the GCE surface was studied through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was observed that the optimized V2O5@f-MWCNT-3 nanocomposite exhibited higher electrocatalytic activity towards PAL, resulting in a wide linear range of detection. The respectable limit of detection (LOD) of the V2O5@f-MWCNT-3 modified GCE was found to be 0.00185 μM and utilized for analyzing PAL in real samples.

Simultaneous determination of trace amounts of dopamine and uric acid in human plasma samples with novel voltammetric biosensor (GCE/Ppy/DEA MIP) following the thin film-µSPE method based on electrospun nanofibers

In order to achieve the aim of this study, i.e., simultaneous measurement of trace amounts of dopamine (DA) and uric acid (UA) following their preconcentration, a novel sorbent with high performance was prepared. Hence, herein, poly vinyl chloride/Mg-Al layered double hydroxide (PVC/Mg-Al LDH) electrospun nanofibers were synthesized for the thin film- micro solid phase extraction (TF-µSPE) and then, simultaneous extraction of trace amounts of DA and UA was done. Finally, DA and UA were determined simultaneously from two different human plasma samples; afterwards, glassy carbon electrode/Poly pyrrole/diethylamine (DA, UA) molecularly- imprinted polymer (GCE/Ppy/DEA (DA, UA) MIP) electrochemical biosensor was constructed. The synthesis confirmation of PVC-Mg-Al LDH electrospun nanofibers was accomplished by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) and attenuated total reflection-Fourier transform infrared (ATR-FTIR). In addition, the GCE/Ppy/DEA MIP and GCE/Ppy/DEA (non-imprinted polymer) NIP nanocomposites were characterized with field emission-scanning electron microscopy (FE-SEM). PVC, as a polymer with a large surface area and high porosity, is an appropriate candidate in the sorbent preparation process with electrospinning. The flexible interlayer region is accessible to various anionic and polar molecular species. Adding Mg-Al LDH led to an extensive surface area of electrospun nanofibers. In the case of Ppy and DEA MIP as GCE surface modifiers, Ppy increased the electroactive sites, leading to the high conductivity of the electrochemical biosensor. Besides, DEA MIP has high selectivity and sensitivity. Optimization of impressive factors on the extraction procedure was conducted by one at-time (OAT) method, and optimum conditions for the construction of electrochemical biosensor were attained with experimental design (design-expert 12.0 software). According to the optimum conditions, the wide linear range was obtained 76.6–268.1 µg mL−1 for DA and 84.1–378.2 µg mL−1 for UA with R2≥ 0.96, low detection limits ranged from 22.3 µg mL–1 for DA and 24.8 µg mL−1 for UA based on S/N = 3 and large enrichment factors. The intra-day (n = 3) and inter-day (n = 3) RSDs% were obtained in the span of 5.3% − 6.1% for DA and 4.0% − 5.6% for UA. Eventually, the efficiency of the TF-µSPE-voltammetric biosensor method was evaluated for the measuring of DA and UA in human plasma samples with satisfactory recoveries (90.2%–99.7%).

An electrochemical aptasensor for the detection of chloramphenicol based on ultra-small Au-inserted hollow PCN-222 MOF.

The excessive utilization of antibiotics has led to significant water contamination and posed severe threats to human well-being. Consequently, the pressing imperative to identify antibiotics in the environment arises. In this study, we have successfully synthesized a hollow PCN-222 MOF distinguished by its substantial surface area and abundant functional groups, particularly the porphyrin cores. To augment the electrical conductivity of the hollow PCN-222 (HPCN-222), gold (Au) particles were incorporated within the porphyrin core using a fundamental hydrothermal method. This modification facilitated the effective immobilization of aptamer strands through π-π stacking and electrostatic interactions. As a result, the Au@HPCN-222 composite demonstrated exceptional efficacy as a substrate for immobilizing the aptamer (Apt) onto the GCE surface. By employing differential pulse voltammetry (DPV) we successfully achieved the detection of chloramphenicol (CAP) with a remarkably low limit of detection of 0.0138ngmL-1 and the peak DPV currents at 0.18V (vs. Ag/AgCl) were used for calibration. Furthermore, this aptasensor exhibited high selectivity and reproducibility.

Fe3O4 nanochips loaded MXenes/g-C3N4 nanocomposite for ultrasensitive electrochemical detection of zinc (II), cadmium (II), lead (II), copper (II) and mercury (II) metal ions

The present work demonstrates a highly sensitive and efficient nanosensor for the simultaneous detection of zinc (II), cadmium (II), lead (II), copper (II) and mercury (II) metal ions using Ti3C2/Fe3O4/g-C3N4 nanocomposite. The Ti3C2/Fe3O4/g-C3N4 nanocomposite was prepared using co-prcepitation method followed by ultrasonication treatment containing Ti3AlC2, ferrous sulfate, ferric chloride and melamine as precursors. The as-prepared nanocomposites were successfully examined using XRD, FTIR, SEM and cyclic voltammetric techniques. Differential pulse anodic stripping voltammetry (DPASV) technique was applied for the simultaneous detection of Zn (II), Cd (II), Cu (II), Pb (II) and Hg (II) ions. The electrochemical variables including pH of the solution, amount of Ti3C2/Fe3O4/g-C3N4 on the GCE surface, supporting electrolyte and deposition time were optimized to get maximum sensitivity. Under optimal conditions, Ti3C2(HF)/Fe3O4/g-C3N4 sensor exhibited excellent performance for Zn (II), Cu (II), Cd (II), Pb (II) and Hg (II) in a range from 0.5 to 0.005 μM with detection limits 0.26 nM for Zn (II), 0.21 nM for Cd (II), 0.10 nM for Pb (II), 0.11 nM for Cu (II) and 0.12 nM for Hg (II) which are lower than the permissible limit recommended by the WHO guidelines. The sensor also shown outstanding selectivity in the presence of various foreign species (Ca2+, Mg2+, Na1+, Cl1-, NO31-, and 4-nitrophenol) and high resolution for simultaneous detection of Zn (II), Cd (II), Cu (II), Pb (II) and Hg (II) ions. The good electroanalytical performance and excellent selectivity and sensitivity of developed nanosensor can be attributed to the heterostructure and the coordination provided by MXene and Fe3O4/g-C3N4, resulting in enhanced interfacial charge transfer and number of adsorption sites. In addition, the developed sensor was applied for the detection of metal ions in tap water samples and satisfactory results were obtained. This study highlights a facile approach for designing MXene-supported magnetic NPs/ N containing carbon materials as sensing platform for the detection of other toxic heavy metal ions.

Electrochemical determination of sulfaguanidine using COOH‐MWCNT coated GC electrode

AbstractThe electrochemical behavior of sulfaguanidine was investigated in PBS buffer aqueous solutions. Cyclic voltammograms have shown that (1) the Sg provided a well‐defined irreversible oxidation peak (2) the signal‐to‐background current ratio is 3 times higher at COOH‐MWCNT coated GCE than that of bare GCE and (3) the modifying GCE surface by COOH‐MWCNT led to a significant improvement (2.7 folds) of the electrochemical response. It has been shown that Sg oxidizes according to a diffusion‐controlled mechanism. A linear calibration curve was obtained for the oxidation of Sg at 10–70 μM. The COOH‐MWCNT coated GCE has also been successfully used for the determination of Sg in real samples.

Electrochemical sensing of doxorubicin hydrochloride under sodium alginate antifouling conditions using silver nanoparticles modified glassy carbon electrodes

Doxorubicin (DOX) is a highly effective anticancer drug with a narrow therapeutic window; thus, sensitive and timely detection of DOX is crucial. Using electrodeposition of silver nanoparticles (AgNPs) and electropolymerization of alginate (Alg) layers on the surface of a glassy carbon electrode, a novel electrochemical probe was constructed (GCE). The fabricated AgNPs/poly-Alg-modified GCE probe was utilized for the quantification of DOX in unprocessed human plasma samples. For the electrodeposition of AgNPs and electropolymerization of alginate (Alg) layers on the surface of GCE, cyclic voltammetry (CV) was used in the potential ranges of −2.0 to 2.0 V and −0.6 to 0.2 V, respectively. The electrochemical activity of DOX exhibited two oxidation processes at the optimum pH value of 5.5 on the surface of the modified GCE. The DPV spectra of poly(Alg)/AgNPs modified GCE probe toward consecutive concentrations of DOX in plasma samples demonstrated wide dynamic ranges of 15 ng/mL-0.1 μg/mL and 0.1–5.0 μg/mL, with a low limit of quantification (LLOQ) of 15 ng/mL. The validation results indicated that the fabricated electrochemical probe might serve as a highly sensitive and selective assay for the quantification of DOX in patient samples. As an outstanding feature, the developed probe could detect DOX in unprocessed plasma samples and cell lysates without the requirement for pretreatment.

A hybrid composite of Polypyrole/carboxymethyl cellulose/MWCNT fiber with antimicrobial properties and Sb3+ determination on a glassy carbon electrode

ABSTRACT In order to prepare fiber-type nanohybrid composites for electrochemical and antimicrobial applications, polypyrrole was combined with carboxymethylcellulose and multiwalled carbon nanotubes (PPy/CMC/MWCNTS). These composite materials were synthesized using ultrasonication and in situ polymerization. By using analytical methods, the structure and morphology of the synthesized nanohybrid composite material were confirmed. Slurry of fiber-type PPY/CMC/MWCNT composites synthesized in ethanol was deposited as a thin-uniform layer with conductive nafion (5% ethanolic solution of nafion) binder. Based on electrochemical measurements in a phosphate buffer medium, Sb3+ ions have linear responses between 0.1 nM and 0.01 mM, which is known as linear dynamic range (LDR). A sensor’s sensitivity (22.4304 µAµM−1cm−2) is calculated using the LDR slope by considering the GCE surface area (0.0316 cm2). A signal-to-noise ratio of 3 is used to estimate the lower limit of detection which is equal to 96.82 ± 4.84 pM. Moreover, the antibacterial activity of the obtained polypyrrole/carboxymethylcellulose/MWCNT composite has also been evaluated “against Gram-positive bacteria B. subtilis along with S. aureus, as well as Gram-negative bacteria, P. aeruginosa along with Escherichia coli by utilizing” autoclave of agar media. In electrochemical analysis, the proposed Sb3+ cationic sensor exhibits appreciable reproducibility, response time, stability, and outstanding outcome in analysis of real samples. In the field of metal ion sensor, this reliable method might be prospective in the recent future.

Simultaneous detection of uric and ascorbic acids by AuNPs electrodeposited on the GCE surface

Simultaneous detection of uric and ascorbic acids by AuNPs electrodeposited on the GCE surface

Electrocatalytic Hydrogen Evolution Reaction from Acetic Acid over Gold Immobilized Glassy Carbon Surface

A hydrogen fuel cell is a highly promising alternative to fossil fuel sources owing to the emission of harmless byproducts. However, the operation of hydrogen fuel cells requires a constant supply of highly pure hydrogen gas. The scarcity of sustainable methods of producing such clean hydrogen hinders its global availability. In this work, a noble Au-atom-decorated glassy carbon electrode (Au/GCE) was prepared via a conventional electrodeposition technique and used to investigate the generation of hydrogen from acetic acid (AA) in a neutral electrolyte using 0.1 M KCl as the supporting electrolyte. Electrochemical impedance spectroscopy (EIS), open circuit potential measurement, cyclic voltammetry (CV), and rotating disk electrode voltammetry (RDE) were performed for the characterization and investigation of the catalytic properties. The constructed catalyst was able to produce hydrogen from acetic acid at a potential of approximately −0.2 V vs. RHE, which is much lower than a bare GCE surface. According to estimates, the Tafel slope and exchange current density are 178 mV dec−1 and 7.90×10−6 A cm−2, respectively. Furthermore, it was revealed that the hydrogen evolution reaction from acetic acid has a turnover frequency (TOF) of approximately 0.11 s−1.

A novel electrochemical sensor for the detection of zearalenone in food matrices using PEGylated Fe3O4 nanoparticles supported by in-silico and multidetector AF4

It is widely known that zearalenone (ZEN) is a carcinogenic mycotoxin that is found in a wide variety of grains, cereals, and dairy products, causing cancer in both humans and animals. Thus, there is a growing demand for sensitive, selective, and inexpensive sensors that can detect toxic mycotoxins in real food samples. In this paper, the impact of PEGylated Fe3O4 nanoparticles (NPs) intercalated with carboxylic acid functionalized multiwalled carbon nanotubes (PEG-Fe3O4 NPs/cMWCNTs) was investigated for the design of an electrochemical sensor for ZEN analysis. Results showed that the nanocomposite-enhanced electrode exhibited a strong cathodic redox response of ZEN using cyclic voltammetry (CV). The developed sensor provided significantly low limits of detection and quantification of 0.34 and 1.12 fg mL−1 respectively over a calibration range of 1.00 to 10.00 fg mL−1 by differential pulse voltammetry (DPV). Excellent spike recoveries ranging from 92 to 106% were obtained for real samples of rice and corn flour. The multidetector Asymmetrical Flow Field-Flow Fractionation (AF4) measurements on the synthesized PEG-Fe3O4 NPs verified their nano-sized dimensions (rg≈ 31 nm) contributing to the exceptionally high electron transfer in DPV sensing. On the other hand, the simulated Monte Carlo (MC) adsorption studies demonstrated that the ZEN/PEG-Fe3O4 NP/cMWCNTs electrode interaction was the strongest on the GCE surface. The charge transfer was further enhanced by the combination of the strong cMWCNTs/GCE platform, due to their inherent conductive properties. The study suggests that the incorporation of the nanocomposite-enhanced electrode can be extended to prevent ZEN mycotoxin exposure.