A novel fluorescence immunoassay based on inner filter effect and gold nanoclusters for Vibrio parahaemolyticus determination

Abstract A novel and sensitive fluorescence immunoassay was developed for the determination of Vibrio parahaemolyticus (VP) based on gold nanoclusters (BSA-AuNCs). The assay signal was originated from inner filter effect (IFE) between BSA-AuNCs and p-nitrophenol (PNP). A double emission peak fluorescent gold nanocluster with good property was quickly synthesized, which was used as fluorescent probe in this method. To achieve the IFE, Alkaline phosphatase labeled second antibody (IgG-ALP), which could generate PNP with the substrate of PNPP (p-nitrophenyl phosphate), was used in the immune reaction. According the competitive reaction, VP could be detected indirectly by the change of fluorescence signal. Under the optimal conditions, the limit of detection (LOD) for VP was 5 × 102 CFU/mL. The linear detection range was 103-107 CFU/mL. Furthermore, the proposed method was successfully applied to detect VP in real samples, giving recoveries in the range of 82.5%–113.0%, and the coefficient of variation was 5.46%–9.88%.