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.