Graphene oxide/silver nanocube composites for SERS detection of biomolecules

Graphene oxide (GO) is regarded as a promising multifunctional building block for the fabrication of GO-metal nanocomposites with enhanced Surface Enhanced Raman Spectroscopy (SERS) activity. Herein we propose the preparation of a well-controlled silver nanocubes (AgNCs) layer covered by a uniform graphene oxide coating as an effective bi-layered substrate for SERS applications. Monodisperse AgNCs were synthesized and a 2D layer of these particles was fabricated by the Langmuir-Blodgett (LB) technique. Adsorption of GO sheets onto AgNCs film was monitored through a Quartz Crystal Microbalance (QCM) experiment until a complete coverage of the nanocube monolayer was achieved. The observed GO membrane-like behaviour can improve the sticking properties of GO toward many bio-molecular species that are still challenging in their SERS detection. SERS experiments were carried out to test the SERS activity of the supported GO/AgNCs platform. A greater reproducibility of the measurements and a higher SERS enhancement factor was observed for GO/AgNCs with respect to naked AgNCs systems.