From hapten design to in situ detection: development of highly specific visual immunochromatographic sensor strips for sulfaguanidine antibiotics in animal sourced foods.

Abstract

Sulfaguanidine (SG), a sulfonamide-based synthetic antimicrobial agent, is widely used in livestock and aquaculture. Due to the presence of N1-guanidinium substitutions in its molecular structure, SG exhibits not only high ecotoxicity but also remarkable stability, making it difficult to degrade in the environment. Consequently, residues of SG can persist in water and soil for extended periods, posing risks of bioaccumulation and biomagnification through the food chain. Therefore, establishing a rapid and sensitive on-site detection method to monitor SG residues is of great significance. However, the unique structure of SG limits the availability of highly sensitive and specific haptens suitable for immunoassays, which hinders the development of rapid immunodetection technologies. To address this challenge, two novel haptens were designed via electrostatic potential, molecular orbitals and immunodeterminant moiety in this study, to optimize the exposure of the unique guanidino group. This approach laid the foundation for establishing a highly sensitive immunoassay for SG. Subsequently, a high-affinity monoclonal antibody, 3G5 (IC50 = 0.11 ng/mL), was obtained via mouse immunization. Based on these findings, a colloidal gold-based visual immunochromatographic assay for SG detection was pioneered. Following simple extraction and dilution procedures, the visual detection limits were 0.2 ng/mL in milk and 1 ng/mL in fish. The method was further validated using real samples, yielding recoveries ranging from 89.1% to 107.5%, confirming the method's applicability for detecting SG residues in complex matrix samples. The present study introduces a novel approach for the sensitive and precise detection of persistent organic pollutants.