Botulinum neurotoxin (BoNT) is a highly lethal toxin produced by the anaerobic bacterium Clostridium botulinum, which leads to nerve paralysis following poisoning. At present, there is no specific drug officially approved. Antibodies, particularly single-domain antibodies, represent safe and effective candidates for specific drugs against BoNT. In this study, the receptor-binding domain of botulinum toxin (BoNT/AHC