Voltammetric sensor based on bimetallic nanocomposite for determination of favipiravir as an antiviral drug

Abstract

A novel and sensitive voltammetric nanosensor was developed for the first time for trace level monitoring of favipiravir based on gold/silver core-shell nanoparticles (Au@Ag CSNPs) with conductive polymer poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) and functionalized multi carbon nanotubes (F-MWCNTs) on a glassy carbon electrode (GCE). The formation of Au@Ag CSNPs/PEDOT:PSS/F-MWCNT composite was confirmed by various analytical techniques, including X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and field-emission scanning electron microscopy (SEM). Under the optimized conditions and at a typical working potential of + 1.23 V (vs. Ag/AgCl), the Au@Ag CSNPs/PEDOT:PSS/F-MWCNT/GCE revealed linear quantitative ranges from 0.005 to 0.009 and 0.009 to 1.95 µM with a limit of detection 0.46 nM (S/N = 3) with acceptable relative standard deviations (1.1-4.9 %) for pharmaceutical formulations, urine, and human plasma samples without applying any sample pretreatment (1.12-4.93%). The interference effect of antiviral drugs, biological compounds, and amino acids was negligible, and the sensing system demonstrated outstanding reproducibility, repeatability, stability, and reusability. The findings revealed that this assay strategy has promising applications in diagnosing FAV in clinical samples, which could be attributed to the large surface area on active sites and high conductivity of bimetallic nanocomposite.

Keywords: Biological sample analysis; COVID-19; Carbon nanotube; Conductive polymer; Favipiravir; Voltammetry.

Fig. 1

Chemical structure of favipiravir

Scheme 1

The chemical structure of Au@Ag CSNPs/PEDOT:PSS/F-MWCNT and its bonds

Scheme 2

The synthesis procedure and sensing of Au@Ag CSNPs/PEDOT:PSS/F-MWCNT/GCE to determine favipiravir

Scheme 3

Au@Ag CSNPs synthesis reaction mechanism

Fig. 2

A UV–Vis absorption spectra of PEDOT:PSS (black line) and Au@Ag CSNPs (red line). B XRD patterns of F-MWCNT and Au@Ag CSNPs/PEDOT:PSS/F-MWCNT

Fig. 3

SEM images of Au@Ag CSNPs/PEDOT:PSS/F-MWCNT (A) and TEM images of F-MWCNT (B), Au@Ag CSNPs (C, D), and Au@Ag CSNPs/PEDOT:PSS/FMWCNT (E, F)

Fig. 4

DPV of Au@Ag CSNPs/PEDOT:PSS/F-MWCNT/GCE in blank (a); bare GCE (b), PEDOT:PSS/GCE (c); Au@Ag/GCE (d); F-MWCNTs/GCE (e); and Au@Ag CSNPs/PEDOT:PSS/F-MWCNT/GCE (f) in the presence of 1.0 µM FAV at pH 4.0, insert, current density diagrams obtained from differential pulse voltammograms data

Fig. 5

(A) CVs and (B) Nyquist plot of EIS for bare electrode (a), PEDOT:PSS/GCE (b), F-MWCNT/GCE (c), and Au@Ag CSNPs/PEDOT:PSS/F-MWCNT/GCE (d) in the presence of 5.0 mM [K₃(CN)]₆^3−/−4 containing 0.1 M KCl

Fig. 6

(A) DPV of 2.0 µM favipiravir at the surface of Au@Ag CSNPs/PEDOT:PSS/F-MWCNTs/GCE in the range 2.0–9.0. (B) Epa’s plot against pH for electro-oxidation of 2.0 µM favipiravir

Fig. 7

(A) CVs of 0.1 mM favipiravir at various scan rate (2.0 to 200.0 mV/s), (B) the plot of I_pa vs. v^1/2, (C) the plot of the log I pa vs. log v obtained, and (D) the relationship between Epa vs. ln v at the surface of Au@Ag CSNPs/PEDOT:PSS/MWCNTs/GCE

Fig. 8

(A) Chronoamperograms of Au@Ag CSNPs/PEDOT:PSS/F-MWCNTs/GCE in the solution containing (a) 500.0 and (b) 600.0 μM favipiravir; (B) Cottrell plots obtained from chronoamperometry; (C) Tafel plot for Au@Ag CSNPs/PEDOT:PSS/F-MWCNTs/GCE in B-R buffer (pH 4.0) with a scan rate of 100.0 mV/s in the presence of 0.1 mM favipiravir

Fig. 9

(A) DPV of favipiravir with various concentrations of FAV ranging from 0.005 to 2.0 µM obtained at Au@Ag CSNPs/PEDOT:PSS/F-MWCNTs/GCE in pH 4.0 B-R at + 1.23 V. (B) Inset: the plot of anodic peak current vs. FAV concentration (n = 3)