Heterologous immunoassay strategy for enhancing detection sensitivity of banned dye rhodamine B in fraudulent food

Abstract Background The high quality of antibody (Ab) is critical for an immunoassay; usually, Ab with low affinity often regarded as a “bad” one in the immunoassay development. How to use develop highly sensitive still huge challenge. Methods In this study, heterologous strategy was designed enhance sensitivity detection banned dye, rhodamine B (RB), fraudulent food. RB could not recognize by pairing homologous coating antigen (Ag). However, showed unexpected specificity and recognition after being replaced Ag. Indirect competitive enzyme-linked immunosorbent assay (icELISA) developed based on strategy. Results limit icELISA chilli powder, Chinese prickly ash, hot-pot seasoning, sauce 0.002 ?g/kg, recoveries four samples ranged from 76.0 102.0%, coefficient variation between 3.9 18.8%. Parallel experiment 20 market high-performance liquid chromatography (HPLC) performed confirm performance practical application icELISA, results two methods had good correlation. Molecular modeling inferred that carboxyl group hapten its exposure level played important role hapten-Ab recognition. Conclusions proposed can be used surveillance screening range seasoning foods, effective approach immunoassay.