Ultrasensitive photoelectrochemical aptasensor for detecting telomerase activity based on AgS/Ag decorated ZnInS/CN 3D/2D Z-scheme heterostructures and amplified by Au/Cu-boron-nitride nanozyme.

Enzyme-mediated signal amplification strategies have gained substantial attention in photoelectrochemical (PEC) biosensing, while natural enzyme on the photoelectrode inevitably obstructs the interfacial electron transfer, in turn deteriorating the photocurrent responses. Herein, Au nanoparticles and Cu-modified boron nitride nanosheets (AuNPs/Cu-BNNS) behaved as nanozyme to achieve remarkable magnification in the PEC signals from a novel signal-off aptasensor for ultra-sensitive assay of telomerase (TE) activity based on AgS/Ag nanoparticles decorated ZnInS/CN Z-scheme heterostructures (termed as AgS/Ag/ZnInS/CN, synthesized by hydrothermal treatment). Specifically, telomerase primer sequences (TS) were extended by TE in the presence of deoxyribonucleoside triphosphates (dNTPs), which was directly bond with the thiol modified complementary DNA (cDNA), achieving efficient linkage with the nanozyme via Au-S bond. The immobilized nanoenzyme catalyzed the oxidation between 4-chloro-1-naphthol (4-CN) and HO to generate insoluble precipitation on the photo-electrode. By virtue of the inhibited PEC signals with the TE-enabled TS extension, an aptasensor for assay of TE activity was developed, showing the wide linear range of 50-5×10 cell mL and a low detection limit of 19 cell mL. This work provides some valuable guidelines for developing advanced nanozyme-based PEC bioanalysis of diverse cancer cells.