CRISPR/Cas13a-Regulated SERS Biosensor Based on Plasmonic-Enhanced Magnetic Rods with Intensified Electromagnetic Field Generation for Breast Cancer Associated miRNA Detection

Early and sensitive detection of breast cancer biomarkers is essential for improving patient prognosis, yet rapid and amplification-free analysis of low-abundance circulating miRNAs remains challenging. Herein, we report a CRISPR/Cas13a-regulated surface-enhanced Raman scattering (SERS) biosensor, termed the CaRER sensor, for on-site detection of miRNA-511-5p, a clinically relevant breast cancer-associated biomarker. To enhance plasmonic activity and SERS performance, Ag, known for its strong SERS amplification capability, was incorporated into Au-Ni-Au magnetic rods to construct plasmonic-enhanced magnetic rods (PEMRs), which generated markedly stronger Raman signals than conventional Au-Ni-Au rods. Integration of PEMRs with the CRISPR/Cas13a system enabled amplification-free and highly sensitive detection through target-triggered trans-cleavage-induced modulation of the SERS signal after sequence-specific recognition of miRNA-511-5p. The CaRER sensor achieved femtomolar-level detection with high selectivity and reproducibility, and reliably distinguished clinical plasma samples from breast cancer patients and healthy controls. In addition, the magnetic properties of PEMRs enabled efficient separation and robust signal readout, improving assay practicality and operational reliability. The incorporation of Au also enhanced antioxidative stability relative to Ag-dominant plasmonic structures, supporting long-term chemical stability and sensing reliability. Owing to the programmability of crRNA, this platform can be readily adapted to diverse nucleic acid biomarkers through simple sequence redesign, highlighting its potential as a versatile point-of-care testing (POCT) tool for cancer diagnostics and liquid biopsy applications.