A Dual‐Mode Colorimetric‐Photothermal Immunoassay for Rapid and Sensitive Detection of Staphylococcus aureus in Real Samples

The presence of Staphylococcus aureus ( S. aureus ) in food poses a serious public health threat due to its heat‐resistant enterotoxins, which remain toxic even after thermal processing. To address this challenge, we developed a dual‐mode colorimetric‐photothermal immunoassay based on platinum‐gold nanoenzymes (Pt@Au NPs) for rapid and sensitive detection of S. aureus in real samples. The anti‐ S. aureus antibody (Ab1) was modified on the surface of Pt@Au NPs to prepare the catalytic signal probe (Pt@Au@Ab1). Based on the double‐antibody sandwich form, the colorimetric‐photothermal immunoassay has dual detection modes. The colorimetric detection mode was based on the absorbance intensity at 651 nm of TMB into oxTMB catalyzed by Pt@Au@Ab1, and the photothermal detection mode was based on the photothermally temperature of oxTMB under 808 nm near‐infrared (NIR) light irradiation via thermal imaging camera. The dual‐mode colorimetric‐photothermal immunoassay has a detection range from 10 CFU/mL to 10 5 CFU/mL with the limit of detection of 10 CFU/mL, respectively. The dual‐mode colorimetric‐photothermal immunoassay provide a rapid diagnostic tool for the determination of S. aureus on‐site detection in multiple scenarios.