Study of graphene incorporation into ZnO-PVA nanocomposites modified electrode for sensitive detection of cadmium

The presence of heavy metals often causes significant health risks, particularly cadmium, which is known for its high toxicity. In this study, a glassy carbon electrode was successfully modified by incorporating ZnO-PVA-Graphene nanocomposite, leveraging the excellent electrical properties and electron mobility of the material. Comprehensive material analysis, including XRD, confirmed that ZnO maintained its hexagonal wurtzite crystal structure despite the addition of graphene. Moreover, FESEM analysis showed that increasing graphene concentration led to a reduction in ZnO particle size by 85, 68, and 52 nm, respectively, accompanied by a decrease in band gap energy, as verified by UV-Vis measurements. Photoluminescence tests were also conducted and the result showed a noticeable blue shift in ZnO-PVA-Graphene nanocomposites compared to ZnO-PVA, specifically in the near band-edge (NBE) UV emission within the 374-379 nm wavelength range. Through I-V characterization, the optimal graphene concentration for cadmium detection was identified as 1.5 wt% in ZnO-PVA-Graphene nanocomposites, showing an approximate ohmic response. Meanwhile, square-wave voltammetry analysis of cadmium concentrations ranging from 0 to 80 ppm produced a coefficient of determination of 0.98926 and a Limit of Detection (LOD) of 9.88 ppm. These results showed the significant potential of ZnO-PVA-Graphene nanocomposites as a promising material for further development as an effective electrode modifier, enhancing the sensitivity of detection systems.

Innovative Graphene-Based Nanocomposites for Improvement of Electrochemical Sensors: Synthesis, Characterization, and Applications

Graphene, renowned for its exceptional physicochemical attributes, has emerged as a favored substrate for integrating a wide array of inorganic and organic materials in scientific endeavors and innovations. Electrochemical graphene-based nanocomposite sensors have been developed by incorporating diverse nanoparticles into graphene, effectively immobilized onto electrodes through various techniques. These graphene-based nanocomposite sensors have effectively detected and quantified various electroactive species in samples. This review delves into using graphene nanocomposites to fabricate electrochemical sensors, leveraging the exceptional electrical, mechanical, and thermal properties inherent to graphene derivatives. These nanocomposites showcase electrocatalytic activity, substantial surface area, superior electrical conductivity, adsorption capabilities, and notable porosity, which are highly advantageous for sensing applications. A myriad of characterization techniques, including Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area analysis, and X-ray diffraction (XRD), have proven effective in exploring the properties of graphene nanocomposites and validating the adjustable formation of these nanomaterials with graphene. The applicability of these sensors across various matrices, encompassing environmental, food, and biological domains, has been evaluated through electrochemical measurements, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). This review provides a comprehensive overview of synthesis methods, characterization techniques, and sensor applications pertinent to graphene-based nanocomposites. Furthermore, it deliberates on the challenges and future prospects within this burgeoning field.

Electrochemical HPLC Determination of Piperazine Antihistamine Drugs Employing a Spark-Generated Nickel Oxide Nanoparticle-Modified Carbon Fiber Microelectrode

In this work, we demonstrate a sensitive high-performance liquid chromatography (HPLC) method for the determination of piperazine antihistamine drugs employing innovative electrochemical detection based on a spark-generated nickel oxide nanoparticle-modified carbon fiber microelectrode built into a miniaturized electrochemical detector. The direct carbon fiber-to-nickel plate electrode spark discharge, carried at 0.8 kV DC, with the nickel electrode connected to the negative pole of the high-voltage power supply, provides extremely fast (1 s) in situ tailoring of the carbon fiber microelectrode surface by nickel oxide nanoparticles. It has been found that nickel oxide nanoparticles exhibit an electrocatalytic effect toward the piperazine moiety electrooxidation process, as confirmed by voltammetric experiments, revealing the shift in the peak potential from 1.25 to 1.09 V versus Ag/AgCl. Cetirizine, cyclizine, chlorcyclizine, flunarizine, meclizine, and buclizine were selected as sample piperazine antihistamine drugs, while diclofenac served as an internal standard. The isocratic reversed-phase separation of the above set was achieved within 15 min using an ARION-CN 3 μm column with a binary mobile phase consisting of 50 mM phosphate buffer (pH 3) and methanol (45/55, v/v). The limits of detection (LOD) were within the range of 3.8-120 nM (for cyclizine and buclizine) at E = +1500 mV (vs Ag/AgCl), while the response was linear within the concentration range measured up to 5 μmol L-1. The method was successfully applied to the determination of piperazine antihistamine drugs in spiked plasma samples.

In-Situ Construction Molecular Imprinting Electrocatalyst of Au-MoO3/Graphene for Bisphenol A Determination with Long-Term Stability

Molecular imprinting (MI) technology has been used in electrochemical analysis technology because of its unique selectivity and specificity. In this work, an electrochemical sensor based on in-situ inorganic MI-Au-MoO3/graphene for bisphenol A (BPA) analysis is designed, where MI-MoO3 is hybridized with graphene nanosheets and Au nanoparticles, and BPA is acted as the temple molecular. Differential pulse voltammetry (DPV) was used to evaluate the sensing performance of the MI-Au-MoO3/rGO sensor toward BPA determination and it is about 2.0 times that of NI-Au-MoO3/rGO. The as-constructed sensor presents a wide linear range from 0.01 to 106.04 μM and a low limit of detection of 0.003 μM. It also displays outstanding stability and repeatability up to 20 days, and can be used to analyze the content of BPA in dust leachate and plastic bottle. This sensor offers a promising strategy for environment pollution and food analysis via MI technology.

Sodium Dodecyl Sulfate-Mediated Graphene Sensor for Electrochemical Detection of the Antibiotic Drug: Ciprofloxacin

The present study involves detecting and determining CIP by a new electrochemical sensor based on graphene (Gr) in the presence of sodium dodecyl sulfate (SDS) employing voltammetric techniques. Surface morphology studies of the sensing material were analyzed using a scanning electron microscope (SEM) and atomic force microscope (AFM). In the electroanalysis of CIP at the developed electrode, an enhanced anodic peak response was recorded, suggesting the electro-oxidation of CIP at the electrode surface. Furthermore, we evaluated the impact of the electrolytic solution, scan rate, accumulation time, and concentration variation on the electrochemical behavior of CIP. The possible electrode mechanism was proposed based on the acquired experimental information. A concentration variation study was performed using differential pulse voltammetry (DPV) in the lower concentration range, and the fabricated electrode achieved a detection limit of 2.9 × 10^-8 M. The proposed sensor detected CIP in pharmaceutical and biological samples. The findings displayed good recovery, with 93.8% for tablet analysis and 93.3% to 98.7% for urine analysis. The stability of a developed electrode was tested by inter- and intraday analysis.

Glucose Incorporated Graphite Matrix for Electroanalysis of Trimethoprim

The antibiotic drug trimethoprim (TMP) is used to treat bacterial infections in humans and animals, and frequently TMP is used along with sulfonamides. However, a large portion of TMP is excreted in its active state, which poses a severe problem to humans and the environment. A sensitive, rapid, cost-effective analytical tool is required to monitor the TMP concentration in biological and environmental samples. Hence, this study proposed an analytical methodology to analyze TMP in clinical, biological and environmental samples. The investigations were carried out using a glucose-modified carbon paste electrode (G-CPE) employing voltammetric techniques. Electrochemical behavior was examined with 0.5 mM TMP solution at optimum pH 3.4 (Phosphate Buffer Solution, I = 0.2 M). The influence of scan rate on the electro-oxidation of TMP was studied within the range of 0.05 to 0.55 V/s. The effect of pH and scan rate variations revealed proton transfer during oxidation. Moreover, diffusion phenomena governed the irreversibility of the electrode reaction. A probable and suitable electrode interaction and reaction mechanism was proposed for the electrochemical oxidation of TMP. Further, the TMP was quantitatively estimated with the differential pulse voltammetry (DPV) technique in the concentration range from 9.0 × 10^-7 to 1.0 × 10^-4 M. The tablet, spiked water and urine analysis demonstrated that the selected method and developed electrode were rapid, simple, sensitive, and cost-effective.