Modular CRISPR−Cas12a-Activated Gold Nanoparticle Assay for Rapid Visual Detection of Hepatocellular Carcinoma-Related miRNAs

MicroRNAs (miRNAs) are emerging biomarkers for early hepatocellular carcinoma (HCC) detection, but most CRISPR−Cas12a assays rely on reverse transcription and preamplification and often lack simple visual readouts. Here, we develop a reverse transcription-free, cleavage-guided strategy that converts miRNA recognition into visual outputs. In the presence of the target miRNA, a scaffold RNA forms an active crRNA that triggers Cas12a trans-cleavage using a preformed dsDNA activator, enabling two readout formats. In a homogeneous non-crosslinking colorimetric assay (mC-NCA), Cas12a cleavage regulates π−π-stacking-mediated gold nanoparticle (AuNP) aggregation to produce a rapid visual colorimetric response. In a heterogeneous versatile lateral flow assay (mC-vLFA), the cleavage of partially hybridized DNA−magnetic bead probes generates a target-dependent test line while maintaining a built-in control line. Using miRNA-21 and miRNA-122 as targets, mC-NCA shows calculated limits of detection (LODs) of 1.62 and 1.64 fM with a linear range of 50 fM−500 pM, whereas mC-vLFA shows calculated LODs of 1.59 and 1.40 fM with a linear range of 10 fM−10 nM. In a preliminary clinical evaluation, both formats show good agreement with reverse-transcription quantitative polymerase chain reaction (RT-qPCR) and clinical assessment while enabling faster detection with minimal instrumentation. Overall, this dual-readout platform couples RT-free CRISPR−Cas12a miRNA recognition with cleavage-directed visual signal transduction, enabling rapid and low-instrument-dependence CRISPR diagnostics for miRNAs.