Recent improvements in enzyme-linked immunosorbent assays based on nanomaterials

As a gold standard technique, enzyme-linked immunosorbent assay (ELISA) organically combines immunoreactions between antigens and antibodies with enzyme catalysis. The use of ELISA has contributed to advances in applications such as clinical diagnosis, food quality control, and environmental monitoring. However, conventional ELISA suffer from the moderate sensitivity and reliance on enzyme activity, which make it impossible to reliably and inexpensively detect trace targets. The nanotechnology boom has yielded exciting developments in designing nanomaterial-based improved ELISA in recent years. In this review, we attempt to comprehensively describe the improvements in ELISA methodology based on nanomaterials, with a focus on the mode of signal detection, such as colorimetric, fluorescent, electrochemical, photothermal, and Raman scattering sensing. We particularly emphasized on how nanomaterials are used as loading carriers, enzyme mimics, and signal reporters. This review concerns on partially representative examples and describes novel concepts and promising applications, rather than being exhaustive. Finally, we outline the challenges and perspectives, hopefully provide brief guideline to develop neotype improved ELISA.