[Paper Review] Electrical probing of COVID-19 spike protein receptor binding domain via a graphene field-effect transistor

Xiaoyan Zhang, Qige Qi+10 more|arXiv (Cornell University)|Mar 27, 2020

Advanced biosensing and bioanalysis techniques54 citations

TL;DR

The paper demonstrates a graphene field-effect transistor immunosensor that rapidly detects the COVID-19 spike protein S1 RBD with high sensitivity and enables screening of high-affinity antibodies in real time.

ABSTRACT

Here, in an effort towards facile and fast screening/diagnosis of novel coronavirus disease 2019 (COVID-19), we combined the unprecedently sensitive graphene field-effect transistor (Gr-FET) with highly selective antibody-antigen interaction to develop a coronavirus immunosensor. The Gr-FET immunosensors can rapidly identify (about 2 mins) and accurately capture the COVID-19 spike protein S1 (which contains a receptor binding domain, RBD) at a limit of detection down to 0.2 pM, in a real-time and label-free manner. Further results ensure that the Gr-FET immunosensors can be promisingly applied to screen for high-affinity antibodies (with binding constant up to 2*10^11 M^-1 against the RBD) at concentrations down to 0.1 pM. Thus, our developed electrical Gr-FET immunosensors provide an appealing alternative to address the early screening/diagnosis as well as the analysis and rational design of neutralizing-antibody locking methods of this ongoing public health crisis.

Motivation & Objective

• Develop a rapid, label-free immunosensor for the COVID-19 spike protein S1 receptor binding domain (RBD).
• Leverage the sensitivity of graphene field-effect transistors (Gr-FET) to enable fast screening/diagnosis.
• Assess the sensor’s limit of detection and its ability to evaluate binding affinities of antibodies against the RBD.

Proposed method

• Fabricate and functionalize a graphene field-effect transistor to host antibody-antigen interactions.
• Use antibody-antigen binding to transduce electrical signals via the Gr-FET for real-time detection.
• Demonstrate detection of the spike S1 RBD with a limit of detection of 0.2 pM.
• Show potential for screening high-affinity antibodies with binding constants up to 2×10^11 M^-1 at 0.1 pM concentrations.

Experimental results

Research questions

• RQ1 Can a graphene field-effect transistor immunosensor rapidly and label-freely detect the COVID-19 spike protein RBD?
• RQ2 What is the detection limit and response time of the Gr-FET immunosensor for RBD?
• RQ3 Can the Gr-FET platform screen for high-affinity antibodies against the RBD and at what concentrations?

Key findings

• Gr-FET immunosensors detect the COVID-19 spike S1 RBD in about 2 minutes.
• The sensor achieves a limit of detection down to 0.2 pM for the RBD.
• The system can screen high-affinity antibodies with binding constants up to 2×10^11 M^-1 against the RBD.
• Antibody-antigen interactions are detected in a real-time, label-free manner.
• Concentration range tested includes down to 0.1 pM for high-affinity antibody screening.