Filtration-Enhanced Dual-Mode SERS Biosensor for Rapid On-Tap Detection of Waterborne Pathogens in Drinking Water

Ensuring the microbiological safety of drinking water is critical for public health and food production. However, the conventional plate counting method is time-consuming and poorly suited for rapid on-site microbial detection. Here, we propose a filtration-enhanced dual-mode surface-enhanced Raman scattering (SERS) biosensor for the rapid, culture-free detection of waterborne pathogens, which can be directly integrated into household faucets. The biosensor combines a porous filter membrane with Au nanoparticles (AuNPs), achieving simultaneous enrichment of waterborne bacteria and significant amplification of SERS signals. The dual-mode design provides a visible colorimetric response, in which the substrate color gradually changes with increasing bacterial load, enabling preliminary semi-quantitative assessment of water contamination. In addition, the biosensor achieved the lowest experimentally detectable bacterial load of 103 CFU/platform. Support Vector Machine (SVM) algorithm was further applied to discriminate different types of pathogens, yielding a classification accuracy of 96%. Practical tests on household water purifiers revealed that microbial contamination accumulated progressively with service time, which was highly consistent with the results obtained by traditional plate counting. The developed biosensing platform provides a rapid (within 10 min), sensitive, and user-friendly tool for on-site monitoring of drinking water safety in household scenarios and food-related environments.