Gold Nanobipyramid-Based Photothermal Immunoassay for Portable Detection of Ochratoxin A in Maize and Grape Juice

Gold nanobipyramids (AuNBPs) have made great progress in photothermal application due to their prominent photothermal conversion ability, but they have not been applied in the field of photothermal immunoassay. Herein, we employ alkaline phosphatase (ALP) to mediate the in situ growth of AuNBPs to construct a convenient photothermal immunoassay method that can achieve portable detection of ochratoxin A (OTA) by using a thermometer. The integration of the classical tyramine signal amplification strategy with the ALP enzymatic reaction enables this photothermal ELISA to detect OTA sensitively with a detection limit of 0.20 ng mL –1 . The practicability of this photothermal immunoassay method is demonstrated by analyzing OTA spiked in maize and grape juice samples. The good performance of this photothermal method indicates the applicability of AuNBPs in the photothermal immunoassay. Additionally, the implementation of this photothermal method does not need any large-scale instruments, which provides a promising method for OTA on-site detection.