Traditional antibody preparation methods rely on animal immunization and experimental screening, often requiring 3-6 months, which cannot meet the urgent demands for antibodies in environmental emergencies or contamination events. Herein, a rapid antibody preparation method was proposed to transform anti-macromolecule nanobodies into high-affinity anti-small molecule (enrofloxacin) nanobodies, based on the high-precision predictive capabilities of AlphaFold, integrated with structural and interaction analysis. The high-precision prediction capability of AlphaFold ensured the accuracy of nanobody structural analysis and targeted modification. Binding structure design enabled the antigen and antibody to adopt an optimal binding conformation. Interaction analysis provided guidance for targeted modifications and served as a tool for evaluating the results. Molecular docking results revealed that the template nanobodies, which initially couldn't dock with enrofloxacin, formed 3-5 noncovalent bonds after modification. Bio-layer interferometry (BLI) assays demonstrated that the equilibrium dissociation constant (KD) of the modified nanobodies ranged from 5.56 ± 0.34 nM to 94.73 ± 4.35 nM, with half-maximal inhibitory concentration (IC50) between 231.9 and 3293.6 ng/mL. Based on the modified nanobodies and BLI platform, the detection of enrofloxacin in marine fish was achieved with a limit of detection (LOD) as low as 59.97 μg/kg. In summary, this study provided a novel perspective for the rapid nanobody preparation, showing significant potential in food safety and environmental monitoring.
Read full abstract