MoS@TiC nanohybrid-based photoelectrochemical biosensor: A platform for ultrasensitive detection of cancer biomarker exosomal miRNA.

As a class of newly identified biomarkers, miRNAs show enormous potential in cancer diagnosis. The sensitive detection of abnormal miRNAs concentration to realize early diagnosis of malignant tumors is a frontier in the field of biosensing. In this work, a photoelectrochemical (PEC) biosensor based on MoS@TiC nanohybrid was fabricated for the ultrasensitive detection of miRNAs. The hybridization of TiC with excellent electron transfer capability significantly enhances the photocurrent response of the PEC biosensor. Moreover, the electrodeposition of Au nanoparticles on the surface of MoS@TiC nanohybrid further enhances the photocurrent. The detection performance of the PEC biosensor has been tested using colorectal cancer-related exosomal miRNA (miR-92a-3p) as the target. The PEC biosensor shows a broad linear detection ranged from 1 fM to 100 nM and a calculated detection limit of 0.27 fM. In terms of selectivity, the PEC biosensor can distinguish miR-92a-3p from mismatched sequences. The 16 continuous radiation source on-off cycles test indicates the high stability of the PEC biosensor. Furthermore, the accurate detection of exosomal miR-92a-3p concentrations of patients and healthy controls demonstrates the clinical feasibility of the PEC biosensor. Based on these outcomes, the PEC biosensor exhibits the prospect of realizing the ultrasensitive point-of-care detection of miRNAs.