Rationally engineered high-performance BiVO4/Ag3VO4/SnS2 photoelectrodes for ultrasensitive immunosensing of CYFRA21-1 based on HRP-tyramine-triggered insoluble precipitates.

A photoelectrochemical (PEC) biosensor capable of detecting cytokeratin 19 fragment 21-1 (CYFRA21-1) was optimized by taking advantage of the powerful conjugate repeats of horseradish peroxidase and tyramine (HRP-tyramine)-triggered enzymatic biocatalytic precipitation (BCP) on high-performance BiVO4/Ag3VO4/SnS2 photoelectrodes. Compared with the ubiquitous BCP strategy, we identified a design supporting conjugate repeats generated by HRP and tyramine-triggered immeasurable insoluble precipitates in the presence of hydrogen peroxide and 4-chloro-1-phenol (4-CN), and the steric hindrance improved sensitivity. Moreover, by virtue of BiVO4, Ag3VO4, SnS2 excellent level matching structure and chemical stability, a heterojunction (BiVO4/Ag3VO4/SnS2) with high light absorption efficiency has been successfully prepared. The novel heterostructure system of BiVO4/Ag3VO4/SnS2 with high detection current and low background signal exhibited high-performance PEC determination. Generally, the hitherto untapped biosensor resource realized the sensitive detection of CYFRA21-1 with a wide linear range from 50 fg/mL to 200 ng/mL, and a detection limit of 15 fg/mL, which illustrated the potential for biotechnological applications.