Surfactant-assisted preparation of nanohybrid for simultaneously improving enzyme-immobilization and electron-transfer in biosensor and biofuel cell

As enzyme-immobilization and electron-transfer are the key factors for fabricating an enzymatic bioelectrode and its devices, we investigated a strategy to simultaneously improve the two aspects by assistance of the cationic surfactant, stearyltrimethylammonium bromide (STAB). By electrodeposition method, we obtained a multifunctional STAB-modified nanomaterial on electrode surface to improve enzyme-immobilization and electron-transfer. On the one hand, STAB could firmly adsorb a substantial number of enzymes via electrostatic interaction in a favorable orientation on the conductive nanomaterial surface for electron-transfer. On the other hand, STAB acts as a dispersant and stabilizer for traditionally conductive nanomaterials (reduced graphene oxide, carbon nanotubes, and gold nanoparticles) to guarantee their unique properties and form a well-conductive network. Electrochemical measurements demonstrated that enzymatic electrodes based on the nanohybrid possessed fast electron-transfer rate, a large quantity of immobilized enzymes, and good activity toward glucose oxidation or oxygen reduction. The glucose biosensor performed linear response range of 0.01–11.71 mM, detection limit of 3.84 × 10 −3  mM, and sensitivity of 10.42 μA mM −1  cm −2 , while the glucose/O 2 biofuel cell exhibited maximum power density of 121.87 μW cm −2 and open-circuit voltage of 0.663 V. Both of the devices showed better performances than those of devices without STAB or conductive nanomaterials in this work. Fabrication of surfactant-modified enzymatic electrode and its electrochemical performance