Integration of DNA-Decorated Hapten in Emergency Immunoassays for Antibody and Small-Molecule Detection: A Review

DNA-decorated hapten (DDH)-based immunoassays have emerged, demonstrating supreme advantages in sensing applications because of their excellent sensitivity, specificity, and reliability. DDH combines both a recognition element (hapten) and a signal transduction element (DNA portion) with its highly programmable DNA structure enabling the trigger of signal transduction following a recognition event, thereby introducing a novel signal transduction mechanism to immunoassays. In this review, we provide a critical overview of recent research in the DDH-based immunoassays, which are designed to detect specific small molecules and antibodies. On the basis of the following events after binding of antibodies to DDH, the reported studies involved with DDH-based immunoassays can be categorized into three groups: (i) DDH-based immunoassay based on DNA conformational switches induced by antibody binding, (ii) DDH-based immunoassay based on co-localization of nucleic acids induced by antibody binding, and (iii) DDH-based immunoassay based on antibody steric hindrance. We also focus on several fundamental elements of DDH-based immunoassays, including the designed DNA structure, principles of signal transformation, and platform of DDH-based immunoassays. Then, the representative applications of DDH-based immunoassays in areas such as food safety, medical diagnostics, and environmental monitoring as well as the challenges and perspectives of DDH-based immunoassays are also explored.