Synergistic electrocatalytic activity of In2O3@FMWCNTs nanocomposite for electrochemical quantification of dobutamine in clinical patient blood and in injection dosage form

Molecular imprinting technology for electrochemical sensing of kasugamycin in food products based on Cu2+/Cu+ stripping current

An electrochemical sensing approach was developed for the detection of the agricultural antibiotic drug kasugamycin. The method involves the construction of an electrochemical sensor comprising molecularly imprinted polymers (MIPs) embedded within a carbon paste (CP) matrix. The MIPs are designed to have imprinted sites that match the size and geometry of the Cu(II)-kasugamycin coordinated complex. Upon removal of kasugamycin, cavities suitable for the drug's entrance are formed within the MIPs. The presence of Cu(II) facilitates the detection of the drug by generating a redox signal of Cu(II)-Cu(I), which can be easily detected using differential pulse voltammetry (DPV). The signal response of Cu(II)-Cu(I) increases in the presence of the drug, promoting the accumulation of Cu(II) ions within the imprinted cavities. Under optimized conditions, the anodic peak (Ipa) signal of Cu(II)-Cu(I) exhibits an increase proportional to the concentration of kasugamycin within the range of 0.15-140 μM. The detection limit (LOD, S/N = 3) achieved is 0.046 μM. The proposed sensor demonstrates several characteristic features including good stability, reliable performance, a low detection limit, and excellent selectivity. The Cu(II)-MIP@CP sensor proved effective in detecting kasugamycin within complex samples like meat, milk, and cucumber, yielding recovery% ranging from 96.0 to 103.8%. Additionally, the relative standard deviation % (RSD%) fell within the range of 2.2% to 4.0%, indicating good precision and reliability.

Sensitive electrochemical determination of quercetin and folic acid with cobalt nanoparticle functionalized multi-walled carbon nanotube

A nanocomposite of cobalt nanoparticle (CoNP) functionalized carbon nanotube (Co@CNT) was prepared and used to modify a glassy carbon electrode (Co@CNT/GCE). Characterization indicates the morphology of Co@CNT is CoNPs adhering on CNTs. With the nano-interface, Co@CNT provides large surface area, high catalytic activity, and efficient electron transfer, which makes Co@CNT/GCE exhibiting satisfactory electrochemical response toward quercetin (QC) and folic acid (FA). The optimum pH values for the detection of FA and QC are 7.0 and 3.0, respectively. The saturated absorption capacity (Γ*) and catalytic rate constant (kcat) of Co@CNT/GCE for QC and FA are calculated as 1.76 × 10-9, 3.94 × 10-10 mol∙cm-2 and 3.04 × 102, 0.569 × 102 M-1∙s-1. The linear range for both FA and QC is estimated to be 5.0 nM-10 μM, and the LODs (3σ/s) were 2.30 nM and 2.50 nM, respectively. The contents of FA and QC in real samples determined by Co@CNT/GCE are comparable with the results determined by HPLC. The recoveries were in the range 90.5 ~ 114% and the total RSD was lower than 8.67%, which further confirms the reliability of the proposed electrode for practical use.

Surface engineering of carbon microspheres with nanoceria wrapped on MWCNTs: a dual electrocatalyst for simultaneous monitoring of molnupiravir and paracetamol

In the present study, nanoceria-decorated MWCNTs (CeNPs@MWCNTs) were synthesized using a simple and inexpensive process. Molnupiravir (MPV) has gained considerable attention in recent years due to the infection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Since some people infected with COVID-19 experience fever and headaches, paracetamol (PCM) has been prescribed to relieve these symptoms. Therefore, there is an urgent need to monitor and detect these drugs simultaneously in pharmaceutical and biological samples. In this regard, we developed a novel sensor based on nanoceria-loaded MWCNTs (CeNPs@MWCNTs) for simultaneous monitoring of MPV and PCM. The incorporation of CeNPs@MWCNTs electrocatalyst into a glassy carbon microsphere fluorolube oil paste electrode (GCMFE) creates more active sites, which increase the surface area, electrocatalytic ability, and electron transfer efficiency. Interestingly, CeNPs@MWCNTs modified GCMFE demonstrated excellent detection limits (6.0 nM, 8.6 nM), linear ranges (5.0-5120 nM, 8.0-4162 nM), and sensitivities (78.6, 94.3 μA μM-1 cm-2) for simultaneous detection of MPV and PCM. The developed CeNPs@MWCNTs electrocatalyst modified GCMFE exhibited good repeatability, anti-interference capability, stability, and real-time analysis with good recovery results, which clearly indicates that it can be used for real-time industrial applications.

Synergistic effect of gold nanoparticles anchored on conductive carbon black as an efficient electrochemical sensor for sensitive detection of anti-COVID-19 drug Favipiravir in absence and presence of co-administered drug Paracetamol

Favipiravir (FVP) is introduced as a promising newly developed antiviral drug against the coronavirus disease 2019 (COVID-19). Therefore, the accurate determination of FVP is of great significance for quality assessment and clinical diagnosis. Herein, a novel electrochemical sensing platform for FVP based on gold nanoparticles anchored conductive carbon black (Au@CCB) modified graphite nanopowder flakes paste electrode (GNFPE) was constructed. Morphological and nanostructure properties of Au@CCB have been investigated by TEM, HRTEM, and EDX methods. The morphology and electrochemical properties of Au@CCB/GNFPE were characterized by SEM, cyclic voltammetry (CV), and EIS. The Au@CCB nanostructured modified GNFPE exhibited strong electro-catalytic ability towards the oxidation of FVP. The performance of the fabricated Au@CCB/GNFPE was examined by monitoring FVP concentrations in the absence and presence of co-administered drug paracetamol (PCT) by AdS-SWV. It was demonstrated that the proposed sensor exhibited superior sensitivity, stability, and anti-interference capability for the detection of FVP. The simultaneous determination of a binary mixture containing FVP and the co-administered drug PCT using Au@CCB/GNFPE sensor is reported for the first time. Under optimized conditions, the developed sensor exhibited sensitive voltammetric responses to FVP and PCT with low detection limits of 7.5 nM and 4.3 nM, respectively. The sensing electrode was successfully used to determine FVP and PCT simultaneously in spiked human plasma and pharmaceutical preparations, and the findings were satisfactory. Finally, the fabricated sensor exhibited high sensitivity for simultaneous detection of FVP and PCT in the presence of ascorbic acid in a real sample.

Effect of bismuth doping on zircon-type gadolinium vanadate: Effective electrocatalyst for determination of hazardous herbicide mesotrione

Pesticides are used to promote the growth of plants and crops by killing weeds and other pests. On the other hand, overused and unused pesticides can leach into groundwater and agricultural lands, easily contaminating water, air, and soil resources. Doping with metal ions is an effective method to improve the catalytic activity of potential electrode materials. In the present study, an electrochemical sensor based on Bi³⁺-doped gadolinium vanadate nanoparticles (GVB NPs) was fabricated for sensitive and selective detection of harmful pesticide mesotrione (MST). The crystalline nature, functional groups, and elemental composition of the prepared electrocatalysts were confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Field-emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) showed that the undoped gadolinium vanadate had a rice-like nanostructure and was designated as GV NRs, while GVB had the morphology of nanoparticles. The fabricated electrode exhibited a well-resolved MST reduction peak in cyclic voltammetry and linear sweep voltammetry (LSV). Bismuth doping effectively enhanced the MST reduction and produced a stronger cathodic current response than bare and GV NRs-modified GCE. Moreover, GVB NPs/GCE show a nanomolar detection limit of 45 nM with a sensitivity of 0.43 μA μM^-1 cm^-2. The proposed sensor showed good repeatability, reproducibility, and stability in LSV analysis. The fabricated MST sensor was successfully applied to the analysis of real samples (river water and corn) with good recovery results.

Synthesis and Characterization of GO/ZIF-67 Nanocomposite: Investigation of Catalytic Activity for the Determination of Epinine in the Presence of Dobutamine

In this study, we prepared graphene oxide (GO)/ZIF-67 nanocomposites. Therefore, GO/ZIF-67 nanocomposites were used as a modifier on a screen-printed electrode (GO/ZIF-67/SPE) for studying the electrochemical behavior of epinine in phosphate buffer saline (PBS) at pH 7.0 with voltammetry techniques. The GO/ZIF-67/SPE showed greater electrocatalytic activities than the bare SPE. As a result, the GO/ZIF-67/SPE was utilized for additional electrochemical examinations. The epinine concentration determination was in the range 9.0 × 10-8 M to 5.0 × 10-4 M, and the limit of detection (LOD) as well as the limit of quantification (LOQ) equaled 2.0 and 6.6 nM, respectively. From the scan rate study, the oxidation of epinine was found to be diffusion-controlled, and the simultaneous detection of epinine and dobutamine were well achieved with the differential pulse voltammetric (DPV) technique. Moreover, the stability and reproducibility of epinine at the GO/ZIF-67/SPE was studied, and the use of the GO/ZIF-67/SPE to detect epinine and dobutamine in real samples was furthermore successfully demonstrated.

Effects of modified fly ash doped carbon paste electrodes and metal film electrodes on the determination of trace cadmium(ii) by anodic stripping voltammetry

Fly ash, as waste from coal combustion, has been effectively modified to improve its adsorption to remove toxic metals, and modified fly ash could be used for electrode modification to improve the sensitivity of the electrode. In this paper, a modified fly ash doped carbon paste electrode for the detection of trace cadmium was first and successfully developed. Several parameters affecting the anodic stripping voltammetric response of Cd(ii) were optimized, such as the composition of the paste, pH of the measurement solution, the concentration of Sb(iii) (or Sb(iii) and Bi(iii)), deposition potential and deposition time. Compared with Sb/MFA-CPE, the square wave anodic stripping voltammetry (SWASV) response of Cd(ii) at Sb/MMFA-CPE had a higher linear range and lower sensitivity. Relative to MFA, MMFA-CPE, due to the introduction of CTAB, provided a larger effective area for interacting with analytes, more binding sites and further facilitating electron transfer at the electrode, and amplified the electrochemical signal. Compared with Sb/MMFA-CPE, the SWASV response of Cd(ii) at Sb-Bi/MMFA-CPE had a higher linear range and similar sensitivity, since mechanisms at bismuth and antimony film electrodes were different. Besides, the electrode reactions of Cd(ii) at bismuth film electrodes involved adsorption phenomena while they were free of adsorption at antimony film electrodes.