CRISPR/Cas12a-Chemiluminescence Cascaded Bioassay for Amplification-Free and Sensitive Detection of Nucleic Acids.

The CRISPR/Cas system has attracted increasing attention in accurate nucleic acid detection. Herein, we reported a CRISPR/Cas12a-chemiluminescence cascaded bioassay (CCCB) for the amplification-free and sensitive detection of human papillomavirus type 16 (HPV-16) and parvovirus B19 (PB-19). A magnetic bead (MB)-linking single-stranded DNA (LssDNA)-alkaline phosphatase (ALP) complex was constructed as the core component of the bioassay. During the detection process, the single-stranded target DNA was captured and enriched by LssDNA and then activated the trans-cleavage activity of Cas12a. Due to the Cas12a-mediated cleavage of LssDNA, ALP was released from the MB, subsequently catalyzing the substrate to generate a chemiluminescence (CL) signal. Given the cascade combination of CRISPR/Cas12a with the CL technique, the limits of detection for HPV-16 and PB-19 DNA were determined as 0.14 pM and 0.37 pM, respectively, and the whole detection could be completed within 60 min. The practicality and reliability of the platform were validated through target-spiked clinical specimens, and the recovery rate was 93.4-103.5%. This dual-amplification strategy-operating without target pre-amplification-featured high specificity, low contamination risk, facile preparation, and robust stability. It provides a novel approach for sensitive nucleic acid detection, with the potential for rapid extension to the diagnosis of various infectious diseases.