Unlocking the potential of quinoline diazonium salts: An electrochemical approach for engineering antimicrobial surfaces

The development of contact-active antimicrobial surfaces is critical for mitigating bacterial colonization on medical devices. Particularly interesting in the field of surface modification are ultrathin organic coatings formed through the process of electrochemical deposition of diazonium salts. In this work, we present a surface functionalization strategy based on the electrochemical deposition of newly synthesized quinoline-derived diazonium salts onto platinum substrates. The diazonium compounds, synthesized from 3- and 8-aminoquinoline precursors, were successfully deposited as robust organic films and characterized using spectroscopic and surface analysis techniques. Morphological changes confirmed effective film formation resulting in nanometer-scale roughness. As-formed coatings displayed significantly lower bacterial viability against Escherichia coli and Staphylococcus aureus when compared with an unmodified Pt surface under identical assay conditions, indicating that diazonium functionalization of quinoline is a decisive determinant of surface bioactivity. By comparing 3- and 8-substituted quinoline diazonium salts, we established a structure deposition function relationship linking cyclic voltammetry signatures and nanoscale film heterogeneity to contact-active antibacterial performance on platinum. These results position quinoline-based diazonium-derived films as a distinct and tunable class of antimicrobial, electrodeposited coatings.