Dual-switchable bioelectrocatalysis synergistically controlled by pH and perchlorate concentration based on poly(4-vinylpyridine) films.

Poly(4-vinylpyridine) (P4VP) films were electropolymerized on a pyrolytic graphite (PG) electrode surface. The cyclic voltammetric (CV) response of ferrocenedicarboxylic acid (Fc(COOH)(2)) at P4VP film electrodes was very sensitive to the pH and perchlorate (ClO(4)(-)) concentration in testing solutions. Fc(COOH)(2) was at the "on" state with a relatively large CV oxidation peak current for the films at pH 4.0 but showed the "off" state with significantly suppressed CV response at pH 7.0. The reversible ClO(4)(-) concentration-sensitive on-off property of P4VP films toward Fc(COOH)(2) at pH 4.0 was also observed. In particular, the influence of pH and ClO(4)(-) concentration on the on-off behavior of the system is not independent or separate but synergetic or cooperative, and the electrostatic interaction between the films and the probe plays a predominant role in deciding the pH- and/or ClO(4)(-) concentration-dependent behavior for the system. The dual-responsive property of the P4VP films toward Fc(COOH)(2) could also be used to control the bioelectrocatalysis of glucose by glucose oxidase. This synergetic-triggered bioelectrocatalysis on the basis of the intelligent interface system may establish a foundation for fabricating novel multiple factor-controllable biosensors based on enzymatic electrocatalysis.