Density Functional Theory Study of the Interaction of Arginine-Glycine-Aspartic Acid with Graphene, Defective Graphene, and Graphene Oxide

This study investigated the interaction between carbon nanostructures, including pristine graphene, defective graphene with monovacancy, graphene oxide (GO), and tripeptide arginine-glycine-aspartic acid (RGD), by density functional theory. The results from the adsorption energy analysis show that the strongest adsorption is observed when RGD is parallel to graphene surfaces, in which graphene interacts with all three functional groups of RGD, including NH3+, COO-, and guanidine. The interaction of NH3+center dot center dot center dot pi was stronger than that of guanidine-NH2 center dot center dot center dot pi and COO-center dot center dot center dot pi. The vacancy improves the ability of graphene to attract RGD because of active dangling C atoms. GO has a stronger interaction with RGD than the pristine and defective graphene because of O-containing groups. The comparison of the GO model with the OH, epoxy, and mixed OH/epoxy groups reveals that various O-containing groups have distinguishing binding abilities with RGD. Water molecules strengthen the interactions between graphene and RGD, whereas they weaken the interaction between GO and RGD. The results provide useful guidance in designing optimal carbon nanomaterial surfaces with specific characteristics that could satisfy the demand for diverse applications of carbon nanomaterials in biomedical fields.