Review-Nanozyme-Based Immunosensors and Immunoassays: Recent Developments and Future Trends

Since the first report in the 1950s, immunosensors and immunoassays with good specificity have got extensive applications in clinical diagnosis, food safety, and environmental monitoring. As a typical type of immunosensors, enzyme-linked immunosorbent assays (ELISAs) are able to offer high sensitivity for target sensing because of the catalytically amplified readouts produced by their enzyme labels (horseradish peroxidase, alkaline phosphatase, et al.). However, the use of these natural enzymes brings some undesired defects to traditional ELISAs, including high cost and short shelflife. Fortunately, the discovery of nanomaterials with enzyme-like catalytic features (nanozymes) provides a potential way to overcome the above shortcomings. By replacing natural enzymes with artificial nanozymes, the developed immunosensors exhibit lower cost, better stability, and easier production along with comparable sensitivity and selectivity. In this regard, the past few years have witnessed the booming development of nanozyme-based immunosensors. Herein, we make a review on currently developed immunosensors and immunoassays where nanozymes are used as promising alternatives to natural enzymes. Progress of nanozyme-based immunosensors made in recent years is summarized according to various signaling modes. Some trends in the field, like the exploration of high-activity single-atom nanozymes to further improve the sensitivity, are discussed as well, hoping to provide some guides for future research.