In-situ construction of hollow double-shelled CoSx@CdS nanocages with prominent photoelectric response for highly sensitive photoelectrochemical biosensor

In this work, we demonstrate a delicate design and construction of hollow double-shelled CoSx@CdS nanocages (CoSx@CdS-HDSNCs) as an efficient and stable photoactive material of photoelectrochemical (PEC) biosensor for detecting cardiac troponin I (cTnI). The novel self-templated strategy started with ZIF-67, in which two distinct sulfide semiconductors were integrated into a hollow heterojunction with uniform interfacial contacts after sequential anion and cation exchange. The unique thin double shell hollow structure, suitable energy band arrangement and stable electron transmission vastly enhanced the ability of light capture and photogenerated electron-hole separation of biosensor. Subsequently, the photoelectric performance of the heterojunction was further enhanced by the deposition of Au nanoparticles (NPs) on the surface of the CoSx@CdS-HDSNCs resulting in surface plasmon resonance (SPR) effect. Based on the excellent CoSx@CdS-HDSNCs, the biosensor exhibits a high sensitivity for detection of cTnI with a wide linear range (0.00016-16 ng mL-1) and low detection limit (38.6 fg mL-1). Besides, the PEC biosensor exhibited satisfactory stability, selectivity, and reproducibility in human serum. And more importantly, our work may provide more unique inspiration for the design of photoactive materials for the future PEC sensing applications.