<i>Thermus thermophilus</i> Argonaute-Mediated Single Particle Counting Platform for Multiplex Cancer-Related Biomarkers Detection

The clustered regularly interspaced short palindromic repeats-Cas (CRISPR-Cas) system has achieved remarkable success in the field of nucleic acid detection, while its Achilles' heel lies in the difficulties encountered in flexibility regarding the multiplex detection. As a sister system of CRISPR-Cas, prokaryotic Argonautes (pAgos) have precise recognition, multiturnover, and more importantly multiple specific cleavage characteristics, which is a potential candidate for the next generation of multiplex detection. Herein, a single particle counting platform was developed for the simultaneous detection of three colorectal cancer-related miRNAs (miR-141, miR-31, and miR-21) by combining single particle inductively coupled plasma mass spectrometry (SP-ICPMS) with the <i>Thermus thermophilus</i> Argonaute protein (TtAgo), with nanoparticles as signal probes for cleavage. The platform demonstrated high sensitivity (aM level) and specificity due to the dual-cycle mechanism of exponential isothermal amplification (EXPAR) and TtAgo cleavage, as well as the combination of TtAgo's specific cleavage capability and the multiplex detection advantages of metal stable isotope tagging. Additionally, the platform showed good robustness in human serum and cell extracts, indicating significant potential in clinical applications.