Molecular Release Associated with Interfacial pH Change Stimulated by a Small Electrical Potential Applied

Electrochemically stimulated molecular release from a modified electrode surface has been studied. The system was based on a buckypaper electrode modified with a molecular layer, which included a linker with a hydrolyzable phenolic ester bond connecting a fluorescent dye to the electrode surface, and with bilirubin oxidase catalyzing O2 reduction. The O2 reduction resulted in the local pH increase, which resulted in hydrolytic cleavage of the linker and release of the dye. The source of electrons for the reduction process can be electronic (potentiostat) or chemical (NADH). The potential applied on the modified electrode (0 V vs. Ag/AgCl) or generated in situ in the presence of NADH was very small, thus allowing the electrochemical process without complications of any side reaction. While the fluorescent dye released from the electrode represents a convenient model, various (bio)molecular species (e. g., drugs) can be released in the similar process. The designed signal-controlled release system represents a general platform for various (bio)molecular delivering processes.