A duple nanozyme stimulating tandem catalysis assisted multiple signal inhibition strategy for photoelectrochemical bioanalysis

A sandwich-type photoelectrochemical (PEC) immunosensor was developed for cytokeratin 19 fragment 21-1 (CYFRA21-1) ultrasensitive detection relying on a multiple signal inhibition strategy. In this work, Bi10O6S9 nanosheet arrays (BiOS) sensitized strontium titanate nanocubes (SrTiO3 NCs) was used as photoactive matrix. Bi10O6S9 with the large specific surface area and narrow band gap could improve the utilization of light to provide strong initial PEC signal. Besides, bovine serum albumin stabilized gold nanoparticles (BSA@Au NPs) anchored on Cu7S4 polyhedron composite (BSA-Au@Cu7S4 polyhedron) was utilized as an effective PEC signal regulator. As a duple nanozyme with the glucose oxidase (GOx)-like activity and the peroxidase-like activity, BSA@Au NPs induced intriguing tandem biocatalytic precipitation (BCP). On the one hand, the BCP could produce precipitations which obstructed the electron transfer between the photoelectrode and electron donor, leading a decrease of PEC signal; On the other hand, the competitive light absorption between BSA-Au@Cu7S4 polyhedron and photoactive matrix caused a further reduction of PEC signal. Generally, the PEC signal was quenched sharply taking advantage of multiple signal inhibition strategy including tandem BCP strategy, competitive absorption of light and steric hindrance, which improved the detection sensitivity of PEC immunosensor. The suggested PEC immunosensor displayed a good linearity in the range of 0.1 pg/mL -50 ng/mL for CYFRA21-1 detection with a low detection limit of 1.12 fg/mL (S/N = 3). The skillful strategy has infinite potential in biological samples analysis.

Automated summary

A sandwich-type photoelectrochemical immunosensor was developed for ultrasensitive detection of CYFRA21-1, relying on a multiple signal inhibition strategy. The sensor showed a low detection limit and good linear range, improving detection sensitivity through strategies such as tandem biocatalytic precipitation, competitive light absorption, and steric hindrance.