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

Graphical abstract 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.

Nanocomposite of gold nanoparticles@nickel disulfide-plant derived carbon for molecularly imprinted electrochemical determination of favipiravir

A molecularly imprinted electrochemical sensor was fabricated for sensitive and selective detection of anti-COVID 19 drug favipiravir (FAV). The sensor is based on the synthesis of biomass-derived carbon (BC) and nickel disulfide nanospheres (NiS2 NS), which were used to decorate glassy carbon electrode (GCE). Then, the gold nanoparticles (AuNPs) were electro- deposited on the surface of NiS2 NS/BC/GCE to enhance conductivity, increase electron transfer, and aid polymerization of p-aminothiophenol (p-ATP) functional monomer. The fabrication steps were characterized using different morphological and electrochemical techniques. Variables affecting the formation of molecularly imprinted layers and the determination of FAV were optimized. Under optimum conditions, the oxidation current (Ipa) was increased upon addition of FAV in the range of 0.42-1100 nM with a limit of detection (LOD, S/N) of 0.13 nM. The as-fabricated sensor possesses several advantages such as high sensitivity and selectivity, good reproducibility, and acceptable stability. Furthermore, the proposed molecularly imprinted –based electrochemical sensor was efficiently applied for the determination of FAV in tablets and human serum samples with recoveries % of 99.2 to 102.1 % and RSDs % in the range of 2.4-3.2 %, which confirms the reliability of the sensor to detect FAV in different matrices.