An Innovative Polymer-Based Electrochemical Sensor Encrusted with Tb Nanoparticles for the Detection of Favipiravir: A Potential Antiviral Drug for the Treatment of COVID-19

Abstract

An innovative polymer-based electro-sensor decorated with Tb nanoparticles has been developed for the first time. The fabricated sensor was utilized for trace determination of favipiravir (FAV), a recently US FDA-approved antiviral drug for the treatment of COVID-19. Different techniques, including ultraviolet-visible spectrophotometry (UV-VIS), cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray Diffraction (XRD) and electrochemical impedance spectroscopy (EIS), were applied for the characterization of the developed electrode Tb_NPs@ poly m-THB/PGE. Various experimental variables, including pH, potential range, polymer concentration, number of cycles, scan rate and deposition time, were optimized. Moreover, different voltammetric parameters were examined and optimized. The presented SWV method showed linearity over the range of 10-150 × 10^-9 M with a good correlation coefficient (R = 0.9994), and the detection limit (LOD) reached 3.1 × 10^-9 M. The proposed method was applied for the quantification of FAV in tablet dosage forms and in human plasma without any interference from complex matrices, obtaining good % recovery results (98.58-101.93%).

Keywords: COVID-19; Favipiravir; Tb nanoparticles; human plasma analysis; m-THB polymer.

Figure 1

The effects of: (A) concentration of m-THB, (B) potential used in the polymerization of m-THB, (C) number of cycles for polymerization of m-THB and (D) concentration of Tb (III) on the current value of FAV (70 × 10⁻⁹ M) using Tb_NPS @ poly m-THB/PGE.

Figure 2

(A) SWVs, (B) CVs curves of FAV (70 × 10⁻⁹ M) recorded on: (a) bare PGE, (b) poly m-THB/PGE and (c) Tb_NPS@ poly m-THB/PGE & SEM images of: (C) bare PEG, (D) poly m-THB/PGE, and (E) Tb _NPS@ poly m-THB/PGE surface.

Figure 3

(A) The effect of different scan rates from 0.1 to 0.9 V s⁻¹ on CVs curves of FAV (70 × 10⁻⁹ mol L⁻¹), Inset: Scan rate calibration plot and (B) Dependence of logarithm peak current (Ip/µA) and the oxidation peak potential (E/V) on the logarithm of scan rate (log ν/Vs⁻¹).

Figure 4

(A) Cyclic voltammograms and (B) Nyquist plot of 1.0 mM of Fe³⁺/Fe²⁺ solution recorded on bare PGE and Tb_NPS@ poly m-THB/PGE electrodes. Working parameters are: scan rate 50 mV s⁻¹ over a potential range of −0.2–0.6 V.