Multiplex pathogenic bacteria detection in food systems using gold-nanoparticles coupled with porous silicon microarray used as a SERS-transducer

Herein, we present a broad SERS-based biosensing platform for multi-target detection via indirect immunoassay. The system employed antibody-functionalized AuNPs linked with an indicative Raman reporter, which were subsequently amplified by a silver-coated porous silicon microarray, employed as the SERS transducer. Under optimized physical parameters and operational conditions, while using a portable Raman device, the bioassay depicted low limits of detection (5, 5, and 4 CFU/mL for Escherichia coli, Staphylococcus aureus, and Bacillus cereus, respectively) spanning the linear range of 101 to 105 CFU/mL. The selectivity of the bioassay was validated against common interfering enteropathogenic species with insignificant cross-reactivity. Subsequently, various food samples, including irrigation water, lettuce, rice, chicken, and milk, were optically assessed while demonstrating recovery rates between 81.4% and 107.1%, with RSD below 8.5% across all studied conditions. Our findings highlight the robustness and applicability of the presented multiplex SERS platform for rapid and accurate detection of bacterial contaminants in complex food systems.