A magnetic CRISPR/Cas12a-SERS nanobiosensor for amplification-free and ultrasensitive detection of norovirus in water and food samples

Background Norovirus (NoV) is the leading cause of foodborne disease outbreaks worldwide, typically spreading via contaminated food and water. Rapid, sensitive, and portable detection of NoV is crucial. Results Here, we presented a magnetic CRISPR/Cas12a-SERS nanobiosensor capable of detecting NoV with high sensitivity, accuracy, speed, and portability. In this nanobiosensor, SERS nanoprobes linked to magnetic nanoprobes via linker single-stranded DNAs (ssDNAs). The presence of NoV nucleic acid triggered Cas12a's trans -cleavage activity, degrading the linker ssDNA. After magnetic separation, the dissociated SERS nanoprobes were efficiently separated from the magnetic nanoprobes. This enhanced the SERS signal in the supernatant, detectable using a portable Raman spectrometer. The detection limit for NoV is 100 copies/mL within 60 min. The nanobiosensor was further assessed in real-world settings, demonstrating excellent sensitivity and selectivity for detecting trace NoV in complex food samples. Significance This approach not only broadens CRISPR-based pathogen detection but also provides a reliable tool for monitoring foodborne viruses. Its potential extends beyond NoV, promising enhanced surveillance of various pathogens in food safety, environmental monitoring, and public health sectors.