DNA release from an electrode surface was stimulated by application of a mild electrical potential (0 V vs Ag/AgCl). The release process was activated by interfacial pH increase originating from H+ consumption during O2 reduction bio-electrocatalyzed by bilirubin oxidase immobilized at the electrode surface. The pH increase resulted in a change of the electrical charge from positive to negative at the surface of SiO2 nanoparticles (200 nm) associated with the electrode surface and functionalized with trigonelline and boronic acid. While the negatively charged DNA molecules were electrostatically bound to the positively charged surface, the negative charge produced upon O2 reduction resulted in the DNA repulsion and release from the modified interface. The small electrical potential for O2 reduction resulting in the interface recharge was allowed due to the bio-electrocatalysis using bilirubin oxidase enzyme. While, in the first set of experiments, the potential was applied on the modified electrode from an electrochemical instrument, later it was generated in situ by biocatalytic or photo-biocatalytic processes at a connected electrode. A multistep biocatalytic cascade generating NADH or photosynthetic process in thylakoid membranes was used to produce in situ a small potential to stimulate the DNA release catalyzed by bilirubin oxidase. The designed system can be used for different release processes triggered by various signals (electrical, biomolecular, and light signals, etc.), thus representing a general interfacial platform for the controlled release of different biomolecules and nanosize species.
Keywords: biocatalytic cascade; biomolecular release; interfacial pH; modified electrode; modified nanoparticles; thylakoid membrane.