Electrical SPR biosensor with thermal annealed graphene oxide: Concept of highly sensitive biomolecule detection

Abstract

(Reduced) graphene oxides as promising 2D materials have been explored extensively to improve the performance characteristics of SPR sensors. Herein, we demonstrate the tuning optical properties of SPR biochips by the combination of two strategies: (i) using gold/reduced graphene oxide (Au/rGO) interfaces prepared by thermal annealing of Au/GO, and (ii) applying external electrical bias via the solid-liquid interface during SPR measurements. We investigated this novel approach by studying a model biological interaction of prostate-specific antigen (PSA) with lectin Concanavalin A (Con A) based on glycan recognition, as the glycan motifs detection is increasingly requested due to the growing knowledge of the importance of glycans in various biological processes and their use as biomarkers. The thermally annealed Au/rGO as a functional layer of SPR chips provides higher signals and 10 times better LOD (limit of detection) compared to Au/GO case. This experimental finding was cross-verified by SPR simulations based on a model combining the optical indices (dielectric parameters) and thicknesses of the GO and rGO thin films obtained from ellipsometry characterizations. In addition, the unique optoelectrical properties of rGO thin films allowed for efficient tuning of the plasmonic intensities by applying an electrical bias at the Au/rGO interface, exploited here to improve the Con A LOD down to 10 ng/ml, what is by 1 order of magnitude better compared to the classic Au chip. The electrical SPR biosensor approach presents a proof-of-concept for future ultrasensitive SPR biosensor platforms.

Keywords

• 2D material
• Electrical SPR biosensor
• Biochip
• Biomarker
• Prostate cancer
• Lectin