Using bimetallic Au@Pt nanozymes as a visual tag and as an enzyme mimic in enhanced sensitive lateral-flow immunoassays: Application for the detection of streptomycin

Because of the advantages of simplicity, cost-effectiveness and visibility, lateral-flow immunoassays (LFAs) have been widely used in the food safety field. However, the low sensitivity of LFAs needs to be solved. Nanozymes have amazing potential for application in biosensors due to their excellent and abundant enzyme-like characteristics. In this study, an [email protected] nanozyme synthesized by a one-step method showed the higher affinity with TMB/H2O2 and higher catalytic efficiency than that of horseradish peroxidase (HRP). For the detection of streptomycin (STR), a typical aminoglycoside antibiotic, a novel LFA based on [email protected] as a visual tag and an enhanced LFA based on the enzyme-like activity of [email protected] by addition of the chromogenic substrate 3-amino-9-ethyl-carbazole (AEC) were established and compared with conventional LFA based on AuNPs. The qualitative limit of detection (LOD) was 1 ng mL−1 for the LFA based on [email protected] as the visual tag and 0.1 ng mL−1 for the enhanced LFA based on the activity of [email protected], in comparison to 8 ng mL−1 for LFA based on AuNPs. Furthermore, the level of streptomycin in milk samples from Zhenjiang City was successfully evaluated by the novel LFA based on [email protected] nanozyme. These results suggest that LFAs based on nanozymes are a promising and effective tool for food safety.