posted on 2021-08-17, 19:33authored byHaoran Shen, Aori Qileng, Hui Yang, Hongzhi Liang, Hongshuai Zhu, Yingju Liu, Hongtao Lei, Weipeng Liu
The
abnormal expression of microRNA (miRNA) can affect the RNA
transcription and protein translation, leading to tumor progression
and metastasis. Currently, the accurate detection of aberrant expression
of miRNA, particularly using a portable detection system, remains
a great challenge. Herein, a novel dual-mode biosensor with high sensitivity
and robustness for miR-21 detection was developed based on the cis-cleavage
and trans-cleavage activities of Cas12a. miRNA can be combined with
hairpin DNA-horseradish peroxidase anchored on a CdS/g-C3N4/B-TiO2 photoelectrode, thus the nonenzymatic
amplification was triggered to form numerous HRP-modified double-stranded
DNA (HRP-dsDNA). Then, HRP-dsDNA can be specifically recognized and
efficiently cis-cleaved by Cas12a nucleases to detach HRP from the
substrate, while the remaining HRP on HRP-dsDNA can catalyze 4-chloro-1-naphthol
(4-CN) to form biocatalytic precipitation (BCP) on the surface of
the photoelectrode, and thus the photocurrent can be changed. Meanwhile,
the trans-cleavage ability of Cas12a was activated, and nonspecifically
degrade the FQ-reporter and a significant fluorescence signal can
be generated. Such two different kinds of signals with independent
transmission paths can mutually support to improve the performance
of the detection platform. Besides, a portable device was constructed
for the point-of-care (POC) detection of miR-21. Moreover, the dual-mode
detection platform can be easily expanded for the specific detection
of other types of biomarkers by changing the sequence of hairpin DNA,
thereby promoting the establishment of POC detection for early cancer
diagnosis.