Graphene and graphene oxide for biosensing

Graphene-based nanomaterials attract large attention in electrochemistry due to their unique properties. Reliable method to modify electrodes by graphene is necessary to obtain desired improvement. In this work, different sizes of graphite flakes for preparation of graphene oxide (GO) were tested and the final characterization of the resulting GO was focused on a quick and reliable methods such as Raman and UV-Vis spectroscopy, atomic force microscopy, and surface plasmon resonance. Smaller particles resulted in bigger yield with higher stage of oxidation. Although the average thickness of GO was similar to 1 nm, differences between GO and by ascorbic acid chemically reduced GO were minimal in topography. The binding and stability of reduced GO on gold surface and gold modified by cysteamine were studied by surface plasmon resonance and cyclic voltammetry. The cysteamine provided slightly higher loading capacity compared to bare gold electrode; however, cyclic voltammetry proved that the electrochemical properties are identical, and therefore, cysteamine is not in this case necessary for GO immobilization.