A nanozyme-linked immunosorbent assay based on Au@CeO2@Pt nanozymes for colorimetric and fluorescent detection of SARS-CoV-2 nucleocapsid protein

Abstract

Developing powerful alternatives to natural enzymes has been a target pursued by researchers, and nanozymes are considered to be the best candidate due to their unique advantages of high stability, high activity, and easy modification. In this study, the multishell complexes of Au@CeO2@Pt nanozymes were successfully synthesized which exhibited an excellent intrinsic peroxidase-like ability to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB), and resulting in a visible colorimetric signal. Interestingly, due to the internal filtration effect, the blue-emitting oxidized TMB (oxTMB) can also quench the red-emitting light from bimetallic AuAg nanoclusters. Based on the above properties, a kind of robust immunoassay for target protein detection was established. The dual-mode immunoassay is more accurate for SARS-CoV-2 detection on account of the reciprocal corroboration of the signals. More importantly, the immunoassay had high sensitivity with a low limit of detection and excellent recovery rates in simulated urine/saliva samples. Therefore, it is highly anticipated the immunoassay based on the newly developed nanozyme became an accurate instrument for diagnosing SARS-CoV-2 in the biomedical field.