Multiple Stimuli-switchable Bioelectrocatalysis Under Physiological Conditions Based on Copolymer Films with Entrapped Enzyme

In the present work, N,N-diethylacrylamide (DEA) and methyl acrylic acid (MAA) monomers were copolymerized into P(DEA-co-MAA) thin films on the electrode surface with a simple one-step polymerization method at ambient temperature and pressure, and the enzyme glucose oxidase (GOD) was entrapped in the films, designed as P(DEA-co-MAA)-GOD. The cyclic voltammetric (CV) response of ferrocene dicarboxylic acid (Fc(COOH)2) at the film electrodes was very sensitive to environmental stimuli, such as temperature, pH, the identity and concentration of anions, and the concentration of CO2 in solution. This multiresponsive CV behavior of the system could be further employed to switch the electrochemical oxidation of glucose catalyzed by GOD entrapped in the films with Fc(COOH)2 as the mediator in solution, demonstrating the amplification effect. The SEM and stereomicroscopy results showed that the multisensitive behaviors of the system were attributed to the structure change of the copolymer films with the stimuli. Specifically, the synergistic effect of temperature and pH was observed, and the hydrogen bonding between PDEA and PMAA components in the copolymer played a key role for this. The present system could be performed under physiological conditions at 37 °C and pH 7.4, which may offer numerous possibilities not only to design new multiswitchable biosensors based on bioelectrocatalysis but also to establish foundations for controlled drug delivery and other medical applications.