A thin organic film electrode as a biomimetic platform for indirect electrochemical study of the anticancer drug vinblastine.

A biomimetic thin organic film electrode (TOFE) electrochemical platform was developed to investigate the interfacial behavior of vinblastine (VBL), a widely used anticancer vinca alkaloid. The system was constructed by immobilizing an organic phase (containing nitrobenzene, decamethylferrocene (DmFc) and a perchlorate-based supporting electrolyte) onto an edge-plane pyrolytic graphite electrode, which, when immersed in an aqueous phase (containing an inorganic perchlorate salt), collectively formed a stable solid|organic|aqueous interface. Although VBL did not exhibit a direct electrochemical response within the TOFE system, its presence significantly altered the voltammetric behavior of the DmFc redox mediator, leading to a marked decrease in DmFc peak currents and enabling indirect analysis. Frequency- and amplitude-dependent square wave voltammetry (SWV) analyses revealed a transition toward a kinetically hindered regime, consistent with VBL adsorption and accumulation at the liquid|liquid interface. The TOFE platform enabled indirect determination of VBL by SWV over the linear range of 5.0-100.0 µmol L-1 with limits of detection of 1.62 µmol L-1 and 1.65 µmol L-1 for the voltammetric scan in anodic and cathodic directions, respectively. Comparison with previously investigated anticancer agents, vincristine and docetaxel, VBL revealed distinct variations in interfacial kinetic behavior, highlighting the ability of the TOFE system to distinguish between pharmaceutical compounds based on their interfacial properties. These findings confirm that TOFE-based electrochemistry provides a reliable approach for probing drug-liquid interface interactions and enables indirect detection of electrochemically inactive species, demonstrating its versatility for both mechanistic investigations and analytical applications in pharmaceutical chemistry.