Tri-Mode CRISPR-Based Biosensor for miRNA Detection: Enhancing Clinical Diagnostics with Cross-Validation

In vitro diagnostics require the accurate detection of disease-associated target biomolecules at ultralow concentrations. A multimode sensing strategy is considered as a potential method for in vitro diagnosis because it allows cross-validation of test results through data complementation and self-calibration, and provides double confirmation. Here, we present a CRISPR/Cas12a-powered trimode biosensor (CPTMB) for ultrasensitive and reliable analysis of miRNA. Briefly, the presence of target miRNA initiates rolling circle extension-driven loop-mediated isothermal amplification (R-LAMP), which subsequently activates the trans-cleavage activity of CRISPR/Cas12a. Then, the hairpin probe (HP) biogate on nucleic acid-functionalized MB@Fe-MOF signal probe was degraded by Cas12a, leading to the release of methylene blue (MB) signal molecules encapsulated within Fe-MOF nanocarriers. Due to the capability of MB to generate output responses across three distinct modes: electrochemical (EC), fluorescence (FL), and ultraviolet-visible spectroscopy (UV-vis), a trimodal sensing system is achieved. Benefiting from the efficient signal amplification capabilities of R-LAMP and CRISPR/Cas12a, this strategy enables rapid detection of target miRNA at femtomolar levels within 70 min. Furthermore, the detection results across the three modes cross-validate one another, thereby enhancing the reliability of the analysis. More importantly, the platform has been successfully applied to miRNA analysis in real samples, and the detection results are in good agreement with those of the standard method RT-qPCR, indicating its great potential in the clinical diagnosis of early-stage cancer.