Enhancing the sensitivity of monoclonal antibody based heterologous coating strategy for the detection of 6-Benzyladenine through the LSPR effect of AuNRs

Abstract

6-Benzyladenine (6-BA), a synthetic plant growth regulator with toxicity, is widely used in agriculture despite its harmful properties. However, the detection of 6-BA remains a challenge due to the insufficient sensitivity of current monoclonal antibodies. In this study, the synthetic pathways of 6-BA hapten were optimized based on the structural analog to introduce a carboxyl spacer arm into the benzene ring and combine with a heterologous coating strategy. Through the molecular simulation and experiments, a monoclonal antibody with extremely high sensitivity (IC50=0.13 ng mL-1) and specificity in that the characteristic structure of the distal purine of the binding protein was easily recognized by the immune system for producing high sensitivity antibody through linking the carboxy spacer arm to the benzene ring. Based on this antibody, a visual colorimetric sensor based on TMB2+ mediated etching of gold nanorods (AuNRs) was further constructed. A linear relationship was established between Δλ of the LSPR peak and the concentration of 6-BA in the range of 0.04 to 0.63 ng mL-1, with a low detection limit of 0.04 ng mL-1. In addition, the accuracy and precision of the immunosensor were further confirmed by the recovery tests (81.0%-92.0%) and the HPLC validation, which showed the potential application of this immunosensor in the rapid detection of 6-BA.