Ultrasensitive real-time detection of SARS-CoV-2 proteins with arrays of biofunctionalized graphene field-effect transistors.

With the growing interest in graphene field-effect transistors (GFETs) for biosensing applications, there is a strong demand for strategies enabling flexible and multiplexed biofunctionalization, as well as highly parallel, real-time electronic readout integrated with microfluidic control. Here we present an approach that addresses these challenges by enabling real-time, parallel monitoring of multiple GFETs integrated on a single microfabricated chip within an automated electronic and microfluidic platform. We demonstrate the capabilities of this approach through ultrasensitive detection of the SARS-CoV-2 spike (S) and nucleocapsid (N) proteins. GFET chips are functionalized via van der Waals assembly using 1 nm-thick molecular two-dimensional (2D) materials - carbon nanomembranes (CNMs) - which enable multiplexed biofunctionalization. The chips are integrated into a custom-developed microelectronic and microfluidic system that allows parallel, real-time, and automated measurements of 15 GFETs. We present in situ biofunctionalization of the GFETs with antibodies, followed by selective detection of the S- and N-proteins with the lowest experimentally detected concentrations of 10 aM for the S-protein and 100 aM for the N-protein and a dynamic range spanning four orders of magnitude. Owing to its versatility, the presented platform is readily adaptable for sensing a wide range of biological and chemical targets.