Well plate-based LF-NMR/colorimetric dual-mode homogeneous immunosensor for Vibrio parahaemolyticus detection.

A 96-well plate-based low-field nuclear magnetic resonance (LF-NMR)/colorimetric dual-mode homogeneous immunosensor was developed for the detection of pathogen bacteria, using Vibrio parahaemolyticus (VP) as a detection template. The signal unit MNS@Ab is graphene oxide (GO) simultaneously loaded with VP antibody and FeO nanoparticles. A 96-well plate coated with VP antibody captures the target VP, which then binds the signal unit to form the immunocomplex. After acidolysed, FeO nanoparticles are transformed into Fe and Fe, so the non-homogeneous system is transformed into a homogeneous one. The addition of KMnO can not only convert Fe into Fe but also provide Mn, improving the detection sensitivity. And, colorimetric analysis can be achieved by the quantitative reduction of KMnO. Under the optimal experimental conditions, the limit of detection was 60 CFU/mL with good selectivity, stability, precision, accuracy, and consistency, providing a simple and reliable detection platform for pathogenic bacteria in food.