Abstract
Unregulated trace pollutants such as pharmaceuticals and their metabolites pose serious environmental risks due to their persistence and poor biodegradability. Diclofenac, a widely used non-steroidal anti-inflammatory drug, exemplifies this problem and underscores the urgent need for highly sensitive analytical devices capable of detecting it at trace levels. Although electrochemical sensors have advanced, new materials and fabrication strategies are still required to achieve reliable, low-level detection. This study presents an initial demonstration of an electrochemically synthesized molecularly imprinted polymer based on methacrylic acid and indium oxide nanoparticles on a glassy carbon electrode. The electropolymerization method provides a rapid, cost-effective route to produce thin, stable molecularly imprinted polymer layers. Particular attention was given to optimizing template removal, a critical step for creating accessible recognition sites. A methanol/acetic acid (1:9) mixture was identified as the most effective solvent system, enabling the complete extraction of diclofenac within 20 minutes by disrupting hydrogen bonding and electrostatic interactions. Morphological and spectroscopic analyses confirmed successful electrode modification, while electrochemical impedance spectroscopy showed reduced charge-transfer resistance. Differential pulse voltammetry quantified an imprinting factor of 1.9 and demonstrated excellent sensitivity, achieving a detection limit of 0.75 nM across a broad concentration range. These findings lay the groundwork for the future development of advanced electrochemical sensors and underscore the potential of methacrylic acid /indium oxide-based molecularly imprinted polymer coatings as a promising strategy for the efficient detection of diclofenac.