Dual-ligand quantum dot biosensor combining IgY antibodies and DNA aptamers for rapid, on-site detection of staphylococcal enterotoxin A (SEA) in food matrices.

This study presents a novel hybrid biosensor integrating chicken IgY antibodies and quantum dot-labeled DNA aptamers for rapid, sensitive detection of staphylococcal enterotoxin A (SEA) in food samples. The system leverages the unique advantages of avian IgY, which avoids false positives from staphylococcal protein A interference, combined with high-affinity aptamers (K d= 84 nM) selected through magnetic bead-SELEX for specific detection. The QD-conjugated aptamer reporter system enables visual fluorescence readout with a detection limit of 1 ng/mL within 45 min, offering a faster workflow, operational simplicity, and an estimated consumable cost of <$1 per test under bulk-production conditions. Validation studies using spiked and field-collected food matrices demonstrated strong agreement with PCR-based analysis, including complete concordance in the 50 tested food samples, supporting the platform's reliability for food safety monitoring. This biosensor represents a significant advancement in point-of-need toxin detection, offering laboratory-grade accuracy in a field-deployable format that requires no specialized equipment, making it particularly valuable for resource-limited settings and routine food safety screening programs.