Dual-signal based immunoassay for colorimetric and photothermal detection of furazolidone

As a point-of-care testing method, lateral flow immunoassays are attracting extensive attentions for antibiotic residue detections; however, immunoassay techniques for qualitative and quantitative detections are limited by the poor sensitivity and requirement for cumbersome quantitative devices. To overcome these limitations, MnO 2 -Au, with an excellent carrying capacity of Au nanoparticles and high photothermal signals, was introduced and a dual-signal immunoassay using colorimetric/photothermal MnO 2 -Au signal probe was proposed for furazolidone (FZD) detection. The dual-signal immunoassay not only enables visual detection relying on color change, but also enables quantitative detection via converting conventional assay signals into heat signals using a thermal infrared imager recording. Based on the excellent light-to-heat conversion activity of the bifunctional MnO 2 -Au, the FZD metabolite of 3-amino-2-oxazolidinone (AOZ) can be qualitatively detected in virtue of colorimetric signals with a visual limit of 1 ng mL −1 and quantitatively detected by photothermal signals with a detection limit of 0.43 ng mL −1 . The dual-signal immunoassay biosensor was well applied in food samples with acceptable recoveries of 80.6–106 %. The immunoassay that integrates colorimetric and photothermal analysis will hold a broader application area in real-time monitoring.