Benzoquinone-modified vertically aligned mesoporous silica for ratiometric electrochemical detection of diclofenac

A ratiometric electrochemical sensor featuring a benzoquinone-modified vertically aligned mesoporous silica film (BQ/VMSF) has been developed for the accurate detection of diclofenac (DCF), a widely utilized non-steroidal anti-inflammatory drug. The design process employed the Electrochemical assisted self-assembly (EASA) technique to grow a thiol-functionalized mesoporous silica film on a carbon screen-printed electrode, which was further modified with benzoquinone via click chemistry. Characterization using Transmission Electron Microscopy (TEM), Fourier-Transform Infrared Spectroscopy (FTIR), Cyclic Voltammetry (CV), and Electrochemical Impedance Spectroscopy (EIS) confirmed the successful synthesis and optimal functionality of the mesoporous structure. In this configuration, benzoquinone serves as an internal redox reference, generating one redox signal, while the electrochemical oxidation of diclofenac produces a second redox signal. The sensor's output is derived from the ratio of these two signals, I_DCF/I_BQ, enhancing its sensitivity and selectivity for diclofenac detection. The sensor, tested through Differential Pulse Voltammetry (DPV), exhibited a linear response range from 1 to 10 μM for diclofenac and a remarkably low limit of detection (LOD) of 0.73 μM. Application of the sensor for diclofenac analysis in pharmaceutical formulations demonstrated recovery rates ranging from 97.68 % to 101.79 % and relative errors below 2.32 %, affirming its practical utility.