Lab-on-PCB-Based Electrical Immunosensing Platform for Point-of-Care Detection of SARS-CoV-2

Abstract

The present work shows a multiplexed lab-on-printed circuit board (PCB) platform for label-free immunosensing of SARS-CoV-2 nucleocapsid and spike antigens based on electrical impedance measurements. The sensor consists of an interdigitated electrode of soft gold integrated on a PCB with microwells for sample loading. A mercaptoundecanoic acid–protein-G-based site-specific biofunctionalization strategy is employed to efficiently immobilize dual antibodies on the device surface toward the sensitive and rapid antigen test of SARS-CoV-2. Electrical impedance measurements carried out in a point-of-care setting using the PalmSens Sensit Smart system that could detect nucleocapsid and spike proteins with a detection limit of 40 and 20 pg each. Experiments with nasopharyngeal swab samples from <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> = 5 healthy and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> = 14 SARS-CoV-2 positive subjects showed significantly different electrical responses for subjects with high viral load ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ct</i> < 25) compared with healthy subjects and control.