Design and Development of Electrochemical Sensors Based on Direct Gold Functionalization of Laser Induced Graphene for Ultrasensitive Detection of SARS-CoV-2
Restricted (Penn State Only)
Author:
Brustoloni, Caroline
Area of Honors:
Electrical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Seyedehaida Ebrahimi, Thesis Supervisor Julio Urbina, Thesis Honors Advisor
The 2019 coronavirus (COVID-19) pandemic impaired global health, disrupted society, and slowed down the economy. Early detection of the infection using highly sensitive diagnostics is crucial in preventing the disease’s spread. In this paper, we demonstrate electrochemical sensors based on laser induced graphene (LIG) functionalized directly with gold (Au) nanostructures for the rapid detection of SARS-CoV-2 with a limit of detection (LOD) and sensitivity of 1.2 ag/mL and 37 %/(log(ag/mL)), respectively. To optimize the sensors, we explore various functionalization parameters to elucidate their impact on the sensitivity, LOD, linearity, and noise. Specifically, we investigate the effect of (i) gold precursor concentration, (ii) crosslinker chemistry, (iii) cross-linker and antibody incubation conditions, and (iv) antigen-sensor interaction (diffusion-dominated mixing vs. pipette-mixing). Our benchmarking analysis specifically highlights the critical role of the mixing method and crosslinker chemistry. We show that pipette-mixing enhances sensitivity and LOD by more than 1.6-fold and 5.5-fold, respectively, compared to diffusion-dominated mixing. Moreover, PBA/Sulfo-NHS/EDC cross-linker improves the sensitivity and LOD by a factor of 1.9 and 2.2, respectively compared to PBASE. We confirmed the sensor performance in artificial saliva. Beyond the ability to detect antigen fragments, our sensors enable detection of antigen-coated virion mimics (which are a better representative of the real infection) down to ultralow concentration of ~5 particles/mL in a 100 μL sample volume. The present study provides valuable insights to optimize the fabrication of a variety of graphene-based electrochemical sensors.
