Electrochemical Detection of Oxalic Acid Using NADES-Based Molecularly Imprinted Polymer: A Simulation-Assisted Approach

A sustainable and selective electrochemical sensor was developed using a natural deep eutectic solvent-based molecularly imprinted polymer (DES-MIP) for oxalic acid (OA) detection. The DES, composed of betaine, citric acid, and glycerol, served as both a green solvent and a functional monomer in the polymerization process. Molecular dynamics simulations revealed favorable spatial configurations and binding interactions between OA and DES components, guiding the imprinting strategy. Coulomb potential analyses further demonstrated preferential attraction of positive ions at the electrode surface, consistent with experimental ion distribution. The DES-MIP-modified screen-printed carbon electrode (SPCE) was characterized using scanning electron microscopy, attenuated total reflectance Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy, confirming successful imprinting and surface functionalization. The resulting DES-MIP/SPCE sensor exhibited a low detection limit of 0.44 μM, a wide linear range from 1.49 to 1000.04 μM, and excellent selectivity compared to the non-imprinted counterpart. Real-sample testing in tomato juice confirmed its practical applicability. This study demonstrates the potential of simulation-guided green polymer design for advanced electrochemical sensing applications.