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.