A Third-Generation Biosensor Based on the Enzyme-Like Activity of Cytochrome c on a Room Temperature Ionic Liquid and Gold Nanoparticles Composite Film

A composite film constructed from gold nanoparticles (GNPs) and a room temperature ionic liquid (RTIL), 1-ethyl-3-methyl imidazolium tetrafluoroborate ([EMIm][BF4]), was prepared directly on the surface of a basal plane graphite (BPG) electrode through a simple dropping technique to form a RTIL/GNPs modified electrode. The results from cyclic voltammetry (CV) suggested that Cytochrome c (Cyt c) could be tightly adsorbed on the surface of the modified electrode. Further, the electrode displays a good promotion for the redox of Cyt c. Direct electrochemical response of Cyt c on the modified electrode can be achieved and a couple of well-defined and nearly reversible cyclic voltammetric peaks of Cyt c can be observed in a phosphate solution. Cyt c adsorbed on the modified electrode surface shows an enzyme-like activity for the reduction of oxygen O2. The reduction peak currents were proportional linearly to the concentration of oxygen. A thirdgeneration biosensor based on the direct electrode transfer of Cyt c can be constructed for the determination of O2.