Insights into the Design of An Enzyme Free Sustainable Sensing Platform for Efavirenz

Abstract

In this study, a new hybrid sensor was developed using titanium oxide nanoparticles (TiO2-NPs) and nafion as an anchor agent on a glassy carbon electrode (GCE/TiO2-NPs-nafion) to detect efavirenz (EFV), an anti-HIV medication. TiO2-NPs was synthesized using Eucalyptus globulus leaf extract and characterized using ultraviolet–visible spectroscopy (UV–VIS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). The electrochemical and sensing properties of the developed sensor for EFV were assessed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The current response of GCE/TiO2-NPs-nafion electrode towards the oxidation of EFV was greater compared to the bare GCE and GCE/TiO2-NPs electrodes. A linear dynamic range of 4.5 to 18.7 µM with 0.01 µM limit of detection was recorded on the electrode using differential pulse voltammetry (DPV). The electrochemical sensor demonstrated good selectivity and practicality for detecting EFV in pharmaceuticals (EFV drugs) with excellent recovery rates, ranging from 92.0–103.9%. The reactive sites of EFV have been analyzed using quantum chemical calculations based on density functional theory (DFT). Monte Carlo (MC) simulations revealed a strong electrostatic interaction on the substrate-adsorbate (GCE/TiO2-NPs-nafion-EFV) system. Results show good agreement between the MC computed adsorption energies and the experimental CV results for EFV. The stronger adsorption energy of nafion onto the GCE/TiO2-NPs substrate contributed to the catalytic role in the signal amplification for sensing of EFV. Our results provide an effective way to explore the design of new 2D materials for sensing of EFV, which is highly significant in medicinal and materials chemistry.

Copper-Modified Carbon Nano-Onions as Electrode Modifiers for the Electroanalysis of the Antiretroviral Drug Efavirenz

“…( 15), this work does not focus on direct clarification of the detailed mechanism of the electrooxidation of EFV, which requires potentiostatic or galvanostatic coulometric analysis for total electrooxidation and conversion of the analyte. Nevertheless, Thapliyal et al [26] and Mthiyane et al [27] have proposed a one electron and one proton electrooxidation mechanism involving the benzoxazine ring to produce a free nitrogen radical at the benzoxazine ring, resulting in possible dimers. Since EFV was first dissolved in methanol and added to an alkaline medium before electrooxidation, the drug molecule may also undergo alkaline hydrolysis to an amino alcohol product which may subsequently undergo electrooxidative dehydration and cyclisation on the CuC/oxi-BNCNO/GCE surface to give a quinoline product [65][66][67].…”

“…As an alternative, electroanalytical methods may provide the required sensitivity and selectivity for the determination of EFV in complex sample matrices while reducing costs and analysis time. The electrochemical determination of EFV has been rarely reported, and analysis was performed only in pharmaceutical formulations and biological samples using voltammetric methods [23][24][25][26][27][28]. Initial studies on EFV electroanalysis were reported on a pencil graphite electrode (PGE) modified with DNA with adsorptive stripping differential pulse voltammetry (AdsDPV).…”

“…Therefore, the detection of EFV using electrode modifiers with high surface-to-volume, catalytic effects, excellent stability, and low toxicity to the environment are much needed. Consequently, nanomaterials such as titanium nanoparticles (TiO 2 ) [27], nickel oxide-zirconium oxide nanocomposite (NiO-ZrO 2 ) [26], and electrochemically reduced graphene oxide grafted platinum nanoparticles (ErGO-Pt NPs) [25] have been used as electrode modifiers to increase the sensitivity and stability of EFV sensors. Using NiO-ZrO 2 nanocomposite, Thapliyal et al [26] obtained a LOD of 1.4 nM with a linear range of 0.01-10 µM.…”

“…The ErGO-Pt NPs improved the electrocatalytic performance of the sensor, while Nafion® improved its stability > 5 days. Nafion® was also employed in another study as a TiO 2 nanoparticle stabiliser for the voltammetric determination of EFV at the lowest concentration of 10nM [27].…”