Universal and High-Speed Zeptomolar Protein Serum Assay with Unprecedented Sensitivity

The accurate detection of trace protein biomarkers is critical for disease diagnosis, healthcare, and pathology research. Currently, the main predicaments of techniques are low sensitivity, prolonged procedures, and the need for specialized devices. Moreover, multistep handling and nonspecific biofouling can lead to high background noise and false positives. To overcome these barriers, a novel ultrasensitive electrochemical platform was developed by combining an electrochemistry approach with the silver mirror reaction to detect proteins at the zeptomolar level. This assay can be accomplished in about only 18 min. As a proof of the concept, human immunoglobulin G (h-IgG) as a model analyte exhibited an ultralow detection limit of 6.31 ag mL^-1 (0.04 zeptomoles mL^-1). This strategy can be exploited as a universal approach for the ultrasensitive detection of various proteins in clinical diagnostics and point-of-care testing.