Development of an atrazine immunoassay based on highly catalytically active Au@PtNPs and specific nanobody

Nanobodies specifically recognizing atrazine were successfully obtained through immunization of alpacas and phage display libraries, and an indirect competitive immunoassay (ic-ELISA) based on nanobodies was constructed with an IC₅₀ of 0.062 μg/mL and a minimum detection limit of 0.01 μg/mL. An Au@PtNPs with excellent colorimetric performance, high catalytic activity, and high stability was synthesized. The combination of Au@PtNPs and nanobodies led to the development of a direct competitive immunoassay (dc-ELISA) with higher specificity, convenience, lower cost and an IC₅₀ value of 0.032 μg/mL which was lower than the ic-ELISA. Based on the Au@PtNPs and nanobodies, a novel LFIA model for qualitative and semi-quantitative detection of atrazine was constructed with a visual detection limit of 5 ng/mL. The present study is of great significance for the construction of atrazine immunoassay combining nanobodies and nanoenzymes, which provides a sensitive, specific, simple and reliable method for the detection of atrazine in the environment.