CRISPR/Cas13a-mediated dual-modal biosensing platform based on the Zn0.5Cd0.5S/Ti3C2 Schottky heterojunction for the sensitive detection of miRNAs-21

MicroRNAs-21 (miRNAs-21), which promote tumor development and invasion by facilitating tumor cell proliferation and inhibiting apoptosis, is identified as a reliable biomarker for early cancer detection and prognosis. Herein, a CRISPR/Cas13a-mediated dual-modal biosensing platform was designed based on the Zn0.5Cd0.5S/Ti3C2 (ZCS/TC) Schottky heterojunction and implemented for monitoring miRNAs-21. Specifically, two-dimensional TC nanosheets with a large surface-to-volume ratio produced ample growth sites for the ZCS nanosphere. Moreover, the formation of Schottky heterojunctions at the ZCS/TC interface, validated by density functional theory calculations, can enhance their photoelectric conversion efficiency, providing a satisfactory initial signal for the subsequent implementation of a photoelectrochemical (PEC) biosensor. Furthermore, with the assistance of the MnO2-mediated CRISPR-Cas13a strategy, the dual-mode detection of miRNAs-21 was initiated via visualization and the use of the PEC biosensor. Under the optimized conditions, the linear range of the biosensor for detecting miRNAs-21 was 0.5 fM-1.0 nM and the detection limit was 0.21 fM. The developed platform can be used for the early detection and monitoring of various diseases, specifically cancer, and help create more research opportunities in this field.