An Immunoassay Utilizing DNA-Coated Cage Protein As a Signal Generator

摘要

Enzyme-linked immunosorbent assay (ELISA) is a conventional immunoassay technique based on a specific interaction between antigens and antibodies. This method has been regarded as a gold standard in detection of disease-related biomarkers in clinical area and has been used for the detection and quantitation of various biomolecules such as peptides, proteins, antibodies, and hormones.3"6 Despite these wide applications, ELISA is often limited because of its relatively low detection sensitivity. Recently, we have developed a microwell plate-based immunoassay, called oligonucleo-tide-linked immunosorbent assay (OLISA).7 OLISA utilizes DNA oligonucleotides conjugated on detection antibodies (dAbs) that mediates the cleavage of fluorogenic RNA probes by RNase H for generation of the fluorescent detection signal (Fig. 1, left). Considering that the DNA strand is the template for the signal generation, the increased number of DNA strands per dAb in the DNA-dAb conjugate would improve the detection sensitivity. In that regard, nanomaterials having multiple reactive sites in a restricted surface area are potentially useful cross-linkers for connecting multiple DNA strands to a dAb, leading to improved detection sensitivity in immunoassays.