ABSTRACT
Knowing how heavily the body is burdened by SARS-CoV-2 infection is all important to avoid tragic outcomes. This demands fast and convenient assays with minimum requirement for instruments and reagents. Therefore, a short synthetic peptide is developed to perform direct serum assay, using portable hand-held potentiostat, in a reagent-less manner. The target is angiotensin converting enzyme 2 (ACE2), a protein secreted by the body into the blood to restrict viral invasion. Specifically, under electrochemical potential scanning, the peptide can covalently capture ACE2 from the serum, and then form a covalent gel-like 2D protein network with the serum proteins, in an ACE2-specific fashion. This formation of a covalent biosensing complex enables sensitive detection in serum samples of SARS-CoV-2 infected patients. The detected serum level of ACE2 can not only serve as an index of viral load, but may also hint at the associated risk of potential male infertility. These results may point to field application of this simple design in the clinical practice in treating COVID-19 in the near future.