Carboxyl-Functionalized, Europium Nanoparticle-Based Fluorescent Immunochromatographic Assay for Sensitive Detection of Citrinin in Monascus Fermented Food

A fluorescent immunochromatographic test strip (FICTS) based on the use of europium nanoparticles (EuNPs) was developed and applied to detect citrinin (CIT) in Monascus fermented food. The sensitivity of the immunoassay to detect CIT was greatly improved by the use of a specific monoclonal antibody to attach EuNPs to form a probe. Under optimum conditions, the visual detection limit was 2.5 ng/mL, and the detection limit of the instrument was 0.05 ng/mL. According to the results, the IC(50) was 0.4 ng/mL. Matrix interference from various Monascus fermented foods was investigated in food sample detection. The immunosensor also demonstrated high recoveries (86.8–113.0%) and low relative standard deviations (RSDs) (1.8–15.3%) when testing spiked Monascus fermented food. The detection results of this method showed a good correlation (R(2) > 0.98) with high-performance liquid chromatography (HPLC). The results showed that the FICTS method could be used as a rapid, sensitive method to detect CIT in Monascus fermented food.