Graphene Covalently Modified by DNA G‑Base

We report here the synthesis and characterization of DNA base guanine (G) covalently modified graphene (termed as GMG) hybrid nanostructures, where for the first time, guanine is covalently attached to graphene nanosheets via a reaction between -NH2 group of guanine and GOCl generated from SOCl2 reacted with -COOH group of graphene oxide (GO). The hybrid GMG nanostructures have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL) spectroscopy. GMG has about one guanine group per 20 carbon atoms on graphene sheets based on XPS analysis. UV–vis spectroscopy of GMG shows weaker peaks centered at 208 and 277 nm, suggesting that the covalent bond between GO and guanine moiety has perturbed the electronic state of the graphene sheets. The electrochemical properties of GMG have been studied by cyclic voltammetry (CV) and galvanostatic charge–discharge measurement, which presents enhanced supercapacitive behavior compared with GO and long-term stability and reversibility, as well as excellent solubility in organic solvents, allowing it to have potential applications in nanoelectronics.