Teaching an old dog new tricks: A lipid membrane-based electric immunosensor for real-time probing of the spike S1 protein subunit from SARS-CoV-2.

Abstract

Fast, cheap, and easy to implement point‐of‐care testing for various pathogens constituted a game changer in past years due to its potential for early disease diagnosis. Herein, we report on the proof‐of‐concept of a simple method enabling in vitro detection of a structural spike protein subunit from the SARS‐CoV‐2 (S1) in aqueous samples. At the core of this discovery lies the well‐known paradigm of monitoring the capacitive current across a reconstituted zwitterionic lipid membrane subjected to a periodic transmembrane potential, followed by the real‐time spectral analysis enabling the extraction of the second harmonic of the capacitive current. Subsequent changes in the amplitude of this harmonic recorded during lipid membrane–S1 interactions were correlated with alterations induced in the inner membrane potential profile by the S1 protein subunit adsorption, and were shown to be augmented by ionic strength, the presence of a specific monoclonal antibody designed against the S1 subunit and the angiotensin‐converting enzyme 2 (ACE2) protein receptor, and uninhibited by the presence of other human serum proteins.