Highly photothermal and biodegradable nanotags-embedded immunochromatographic assay for the rapid monitoring of nitrofurazone

Immunochromatographic assay platforms are up-and-coming detection tools for disease diagnosis and harmful substances monitoring in food. Herein, by combining photothermal imaging and immunochromatographic analysis, a photothermal immunoassay is developed for the rapid and ultrasensitive detection of nitrofurazone. The nickel disulfide nanosphere with excellent biocompatibility, biodegradability, and high photothermal conversion efficiency, is introduced to offer straightforward readout by color and temperature based on the nature of the crystal, without advanced equipment. It is demonstrated that the nitrofurazone metabolite of semicarbazide can be qualitatively detected by colorimetric signals with a visual limit of 2 μg kg-1. And the quantitative detection limit of photothermal signals is 0.01 μg kg-1, improving the detection sensitivity by about 200 times. Furthermore, recovery rates of the proposed method in food samples were 93 %-120 %. This photothermal immunoassay not merely provides straightforward, rapid, simultaneous qualitative/quantitative detection tactics but may also be valuable in automated and portable diagnostic applications.