Integrated\nAntibody with Catalytic Metal–Organic\nFramework for Colorimetric Immunoassay

Abstract

Enzyme-linked\nimmunosorbent assay has been widely used as a gold\nstandard in biomedical field, but some inevitable drawbacks still\nexist in its practical applications, especially the laborious preparation\nof enzyme–antibody conjugates by a covalent linkage. In this\nwork, we proposed a new strategy to prepare enzyme–antibody\nconjugate by integrating antibody with catalytic metal–organic\nframework (MOF) to form dual-functional MOF/antibody composite. As\nmodels, rabbit antimouse immunoglobulin G antibody (RIgG) and Cu-MOF\nwith peroxidase-like activity were used to fabricate RIgG@Cu-MOF composite\nfor colorimetric immunoassay. It was found that Cu-MOF as a host not\nonly has no influence on the original capture ability of RIgG to its\ncorresponding antigen (mIgG), but also can shield RIgG against long-term\nstorage, high temperature, and biological degradation. More importantly,\nupon the formation of sandwiched immunocomplex between RIgG@Cu-MOF\nand capture antibody, Cu-MOF can serve as a signal amplification unit\nto perform colorimetric immunoassay. The detection limit of RIgG@Cu-MOF\ntoward mIgG was obtained at 0.34 ng/mL, which is 3-fold lower than\nthat of horseradish peroxidase labeled RIgG. Furthermore, the successful\ndetermination of mIgG in serum sample demonstrates the applicability\nof RIgG@Cu-MOF in detecting real sample. Therefore, it is highly anticipated\nthat this study can offer a new way to prepare enzyme–antibody\nconjugates, facilitating the exploration of MOF composites in biomedical\nfield.