Electrochemical Pretreatment and Functionalization of Pencil Graphite Electrodes for Enhanced Transducer Performance in Biosensing

This study aimed to optimize the electrochemical pretreatment and functionalization of pencil graphite electrodes (PGEs) for the performance evaluation of a transducer applied in initial studies in the development of an immunosensor for vaccinia virus (VACV) detection. The effects of the applied potential, duration, and supporting electrolyte type and concentration on PGE activation were investigated. Functionalization using a polymeric film derived from 2-hydroxybenzamide (2-HXB) was optimized by varying the applied potential, deposition time, and monomer concentration. Optimal activation conditions were found to be +0.90 V in 0.02 M of H2SO4 for 300 s, promoting the formation of hydrogenated groups and increasing electrode wettability. For electropolymerization, +1.20 V for 300 s with a 2-HXB concentration of 2.50 mM provided the best results, ensuring proper film formation and adhesion. Scanning electron microscopy revealed a rough, sheet-like surface on the polished PGE, while energy dispersive spectroscopy confirmed poly(2-HXB) adsorption through increased oxygen and nitrogen content on the functionalized electrode. The optimized pretreatment and functionalization conditions significantly influenced the response of the transducer used for VACV detection, demonstrating its crucial role in device development. These findings contribute to the advancement of inexpensive and effective electrochemical transducers and highlight the importance of pretreatment and modification of PGEs in biosensing applications.