Graphene-mediated Surface Enhanced Raman Spectroscopy and Detection of Biomolecules

In this work, we prepare graphene-mediated surface-enhanced Raman scattering (G-SERS) platforms comprising few-layer graphene nanosheets decorated gold nanoparticle for biomedical and bio-nanotechnology. Raman scattering is surface-sensitive and nondestructive inelastic light scattering vibrational spectroscopy technique. SERS, a specialized form of Raman spectroscopy, is useful for rapid and precise identification of small biomolecules and industrially relevant chemical dyes at ultralow concentration. This phenomenon is due to enhanced Raman signals by several orders of magnitude on the SERS-active surfaces. While the key point of SERS technology is the metal nanoparticles, which generates localized surface plasmon resonances in response to laser exposure and the resulting electromagnetic enhancement, controlling interparticle gap, the diameter of the metal nanoparticles and their ratio on graphene supports offer an advance toward sensitive G-SERS platforms via localized hybridization at graphene-metal interface. We have used low temperature thermal reduction technique to produce few-layer functionalized graphene supports and wet chemistry for size tunable gold nanoparticles as cost-effective facile synthesis approaches for G-SERS platforms. Simple and high-throughput arrays (so-called ‘biochip’) are developed by decorating graphene nanosheets with gold nanoparticles as well as sandwiching gold nanoparticle and few-layer graphene for cascaded signal amplification to differentiate nucleotide bases (adenine; A, thymine; T, cytosine; C, guanine; G) and to detect beta-carotene and malachite green chemical dye