High sensitivity immunoassays for small molecule compounds detection – Novel noncompetitive immunoassay designs

This review focuses on novel, highly-sensitive, non-competitive immunochemical designs for detection of small molecule compounds (SMCs). According to immunochemistry theory, a common and apt protocol for SMCs is the competitive assay. However, it suffers several technical disadvantages due to the single recognition epitope. For higher sensitivity investigations, lots of novel non-competitive designs were reported and discussed for detection of SMCs in recent decades. The proposed non-competitive designs were summarized into six modes in this work. Based on the non-competitive designs, SMCs were monitored with higher sensitivity and stability than previously, and across a broader linear detection range. These new technologies and the challenges encountered in development are discussed, in order to highlight the future prospects of each protocol. We aim to guide the choice of different detection methods and inspire new ideas for SMCs.