Work

Study of the sensitization mechanism of immunoassay based on DNA tetrahedron spatial mediation for detecting imidacloprid in vegetables

Year: 2025

Type: article

Abstract: Introduction Enzyme-linked immunoassay (ELISA) is a widely adopted method for detecting pesticide residues such as imidacloprid because of its speed, low cost, and simplicity. However, antibody adsorption immobilization on solid-phase surfaces often leads to spatial crowding, resulting in reduced accessibility of antigen-binding sites and compromised assay sensitivity. Objective This study aimed to address the limitations of conventional immunoassays by introducing DNA tetrahedron (TDN) as spatial mediators. Spatial mediation of antibodies using TDN allows for sequential targeting and full exposure of the antibody to the recognition site. Methods Firstly, the sequence of TDN was designed using python language. And then, the TDN was labelled on the surface of magnetic beads (MBs) for spatial mediation orientation of antibody to form MB@TDN@Ab immunoprobe, exposing the specific recognition Fab region of the antibody. The sensitization mechanism of immunoassay based on TDN spatial mediation was explored for detecting imidacloprid in vegetables. Results The MB@TDN@Ab immunoprobe acquired a higher affinity constant (Dissociation equilibrium constant (K d ) = 3.21 µg/mL) than MB@Ab immunoprobe (K d = 19.16 µg/mL). The immunoassay based on TDN spatial mediation achieved an IC 50 (1.40 ng/mL) and a linear detection range (0.05 ∼ 50 ng/mL). Compared with the immunoassay based on MB@Ab immunoprobe (IC 50 = 2.66 ng/mL and linear range = 0.05 ∼ 5 ng/mL), the sensitivity and linear range immunoassay based on MB@TDN@Ab immunoprobe are much higher and broader. Conclusion A convenient, efficient and sensitive immunoassay was established for detecting imidacloprid in vegetables in the study. The MB@TDN@Ab immunoprobe improves immunoassay performance while supporting safer food monitoring practices. These findings contribute to sustainable agricultural safety, public health assurance, and innovation in biosensing technologies.

Source: Journal of Advanced Research

DOI: 10.1016/j.jare.2025.06.082