Co3O4 Au polyhedron mimic peroxidase and cascade enzyme assisted cycling process based photoelectrochemical biosensor for monitoring of miRNA 141
Abstract A photoelectrochemical (PEC) biosensor was constructed based on cascade enzyme assisted cycling process and Co3O4 Au polyhedron for miRNA 141 detection. The biotin modified DNA was immobilized on ITO/TiO2/Bi2S3 to link streptomycin modified Co3O4 Au through the specific interaction between streptavidin and biotin. The Co3O4 Au with the competitive consumption effect of electron donor and excitation light energy could effectively reduce the photocurrent signal. Additionally, Co3O4 Au as peroxidase mimetics enzyme could catalyze the formation of benzo 4 chlorohexanedione (4 CD) precipitate on the electrode surface, which could efficiently prevent electron transfer and decrease the photocurrent signal of PEC biosensor. In the cascade enzyme assisted cycling process, a small amount of miRNA 141 triggered the double strand specific endonucleases assisted cycling process, which could generate DNA fragment for next step experiment. Then the biotin modified DNA was decomposed by Exonuclease III (Exo III) in the Exo III assisted cycling process, resulting in the separation of biotin from the electrode surface and the reduction in the loading of streptomycin modified Co3O4 Au. The fabricated PEC biosensor with a wide linear range and a low detection limit has potential applications in highly accurate and ultrasensitive monitoring of bioanalysis and disease diagnostics.