A colorimetric sensor for Staphylococcus aureus detection based on controlled click chemical-induced aggregation of gold nanoparticles and immunomagnetic separation

Staphylococcus aureus ( S. aureus ) is a pathogen closely associated with foodborne diseases. We prepared a reliable colorimetric sensor to detect S. aureus using click chemical reaction and immunomagnetic separation. Aptamer-functionalized and ALP-labeled Fe 3 O 4 NPs act as separation and signal transduction elements. Under the optimized conditions, the Cu + generated by signal transduction triggers a click chemistry reaction, which causes the aggregation of azides and alkyne-AuNPs and a color change. The net extinction ratio of Δ(A 530 / A 760 ) was linearly correlated with the S. aureus concentration from 10 to 10 6 cfu mL −1 , and the limit detection was 2.4 cfu mL −1 . The recoveries were 91.15 ~ 106.36% for the analysis of spiked food and water samples without pre-enrichment. Therefore, we believe that the detection platform can be easily and accurately used for S. aureus detection, providing a broad prospect for on-site visual detection. Graphical abstract