An atomic charge model for graphene oxide for exploring its bioadhesive properties in explicit water.

Graphene Oxide (GO) has been shown to exhibit properties that are useful in applications such as biomedical imaging, biological sensors, and drug delivery. The binding properties of biomolecules at the surface of GO can provide insight into the potential biocompatibility of GO. Here we assess the intrinsic affinity of amino acids to GO by simulating their adsorption onto a GO surface. The simulation is done using Amber03 force-field molecular dynamics in explicit water. The emphasis is placed on developing an atomic charge model for GO. The adsorption energies are computed using atomic charges obtained from an ab initio electrostatic potential based method. The charges reported here are suitable for simulating peptide adsorption to GO.

Favorable adsorption of capped amino acids on graphene substrate driven by desolvation effect.

The use of graphene-based nanomaterials is being explored in the context of various biomedical applications. Here, we performed a molecular dynamics simulation of individual amino acids on graphene utilizing an empirical force field potential (Amber03). The accuracy of our force field method was verified by modeling the adsorption of amino acids on graphene in vacuum. These results are in excellent agreement with those calculated using ab initio methods. Our study shows that graphene exhibits bioactive properties in spite of the fact that the interaction between graphene and amino acids in a water environment is significantly weaker as compared to that in vacuum. Furthermore, the adsorption characteristics of capped and uncapped amino acids are significantly different from each other due to the desolvation effect. Finally, we conclude that when assessing protein-surface interactions based on adsorption of single amino acids, the minimum requirement is to use capped amino acids as they mimic residues as part of a peptide chain.