Green electrochemical nanosensor platform design for mexiletine detection based on Citrus reticulata peel-mediated iron nanoparticles and quantum dots and investigation of the adsorption mechanism by the DFT-D3 method

Abstract

Green nanoparticle production is widespread, dependable, affordable, and ecologically beneficial. Citrus reticulata shells were used to synthesize FeNPs and CQDs. Using a simple procedure, the nanosensor platform was formed by modifying the synthesized FeNPs and CQDs onto the surface of a glassy carbon electrode (GCE). Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were all used to evaluate the nanomaterials in detail. Also, differential pulse voltammetry (DPV) and chronocoulometry methods were used to investigate the modified electrodes. AdSDPV was used to analyze mexiletine using the modified electrode of CQDs/FeNPs/GCE. Green nanomaterials in electrochemical nanosensors improve electron transport and electrocatalytic activity towards mexiletine oxidation. The CQDs/FeNPs/GCE increased the electro-oxidation peak current of mexiletine by 18 times compared to the bare GCE. Both standard and serum samples respond linearly to mexiletine at concentrations between 1.0 × 10⁻⁷ M and 1.0 × 10⁻⁶ M under optimum circumstances. 8.19 × 10⁻⁸ and 6.14 × 10⁻⁸ M were the detection limits. The sensor identified mexiletine in serum with 99% accuracy. It exhibits excellent repeatability and long-term stability. Furthermore, the mechanism of physical adsorption of mexiletine onto the Fe₂O₃ NP@CQD electrode surface was studied using Dispersion-Corrected Density Functional Theory (DFT-D3). Negative adsorption energy with the value of −5.51 eV indicates stable adsorption of mexiletine on the electrode surface.