A portable immune-thermometer assay based on the photothermal effect of graphene oxides for the rapid detection of Salmonella typhimurium.

Previously reported photothermal strip test methods generally used a membrane as the antibody carrier and a thermal imaging camera or sensor as detector. To further simplify the detection device, a modified mercury head of the glass thermometer can act as the antibody carrier. Meanwhile, the temperature variation signal (ΔT) generated by the photothermal effect of labeled nanomaterials can be detected by the thermometer directly. Thus, the antibody carrier and detector can be integrated on a portable and cheap thermometer, which greatly simplified the device and detection steps of the photothermal method. The excellent photothermal effect of graphene oxides was used to improve the detection sensitivity. The main parameters of the performance of immune-thermometer assay were optimized and the Salmonella typhimurium was chosen as the representative target. Under the optimized conditions, the ΔT and the different number of Salmonella typhimurium were plotted to establish the standard curve. The detection limit was estimated to be 10 CFU·mL. The entire detection operation was consistently finished in 15 min. Overall, the proposed immune-thermometer exhibited good precision, selectivity and acceptable stability. The immune-thermometer assay was also successfully implemented and validated in different foodstuffs, which showed that it can be used as a novel and promising technique for rapid, simple and on-site screening of hazards in food, biological, clinical or environmental samples.