Biomineralization–powered integrated immunoprobe and its application in Immunochromatographic assay

Immunochromatographic assay (ICA) has attracted widespread attention owing to its advantages of economy, simplicity, and rapidity. However, the synthesis of immunoprobes is still limited by complicated design ideas and multistep operations from preparing nanoparticles to conjugating monoclonal antibodies (mAb) onto nanoparticles. Inspired by the biomineralization of zeolitic imidazolate framework-8 (ZIF-8), we proposed a strategy for the rapid synthesis of an integrated immunoprobe (ZIF-8@QDs-mAb), achieving a one-step integration with strong fluorescent signal output capability and specific recognition ability. In addition, different fluorescent colors of ZIF-8@QDs-mAb were generated by doping red and green quantum dots (QDs) in various ratios. With a smart detection platform, the developed ZIF-8@QDs-mAb-based multiplex ICA (ZIF-8@QDs-mAb-mICA) achieved the on-site quantitative detection of enrofloxacin, sulfamethazine, and kanamycin in milk within 15 min, with the limit of detection (LOD) of 0.052, 0.186 and 0.216 ng mL-1, which were 5.69, 2.20 and 4.40 times higher than that of gold nanoparticles-based mICA, respectively. The quantitative detection of alpha-fetoprotein and human chorionic gonadotropin was also achieved with LOD of 0.516 ng mL-1 and 0.225 mIU mL-1, respectively, which verified the universality of the strategy. This work provides a novel idea for the design of an efficient integrated immunoprobe and has broad application prospects in ICA.