UV‐Triggered Barcode–CRISPR Cascade Biosensor for Amplification‐Free and Ultrasensitive Programmable microRNA Profiling in Lung Cancer

Early screening and postoperative prognostic evaluation are essential for improving clinical outcomes in lung cancer. MicroRNAs (miRNAs) have emerged as promising minimally invasive biomarkers, and combined analysis of multiple miRNA markers can provide a comprehensive assessment of disease status. Here, we report an ultrasensitive magnetic biosensor that integrates optically triggered bio‐barcode assay (OBCA) with the CRISPR/Cas12a system for amplification‐free miRNA detection. Upon UV irradiation, a photolabile linker undergoes photocleavage to release DNA barcodes that activate Cas12a trans‐cleavage, generating cascade signal amplification without reverse transcription or enzymatic pre‐amplification. Detection performance is further enhanced through the synergistic integration of magnetic separation, thermal denaturation, and UV‐triggered bio‐barcode release within a magnetic bead–silver nanoparticle core–satellite architecture. The platform achieved femtomolar‐level detection limits for miR‐21, miR‐155, and miR‐210, and exhibited excellent specificity toward single‐base mismatches and precursor sequences. Using a portable fluorometer, the biosensor effectively distinguished preoperative patients from healthy controls and postoperative patients, showing strong concordance with RT‐qPCR. Overall, this work presents a simple, efficient, and programmable point‐of‐care platform for adaptable miRNA analysis, with potential for lung cancer‐related biomarker evaluation and postoperative monitoring, particularly in resource‐limited settings.