Graphene as a Surface Enhancement Raman Scattering (SERS) Substrate

Abstract

Hleko Chauke, Sanele Nyembe, Nikiwe Mhlanga, Nosipho Moloto, Lucky Sikhwivhilu

The discovery of surface-enhanced Raman spectroscopy (SERS) presents an opportunity for the development of ultrasensitive biosensors. SERS allows for fingerprint detection of biomolecules at low concentrations and can perform single-molecule detection. The most used SERS substrates are Plasmonic metal nanostructures such as Au and Ag mainly because of their superior electrical conductivity. The Plasmonic metal nanoparticles enhance the Raman signal of the target biomolecules through the electromagnetic field mechanism. Despite the successful use of metal nanostructures, alternative materials have been sought which can exhibit similar or better properties than their metal counterparts. Materials such as graphene which has excellent electrical properties and high surface area are good candidates for SERS applications. Graphene is a 2D nanomaterial consisting of sp2 hybridized carbon atoms. The use of graphene in SERS is termed graphene-enhanced Raman spectroscopy (GERS) and is reported to use a charge transfer mechanism. Both graphene and metal nanostructures can be used together as SERS substrate and the synergistic effect of their mechanism can improve the enhancement factor and the sensitivity of the biosensor, however, the use of graphene as a SERS substrate is still at an early stage. GERS can be applied in disease diagnosis, detection of food additives, and biological species biosensors. The use of GERS in biosensors such as glucose biosensors presents an opportunity for ultrasensitive biosensors which can greatly improve the lives of individuals living with diabetes. In this review insights will be given on how to successfully circumvent the challenges associated with small Raman cross-section of glucose detection for use in medical application.

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