Adhesion of protein residues to substituted (111) diamond surfaces: An insight from density functional theory and classical molecular dynamics simulations

Protein-repellent diamond coatings have great potential value for surface coatings on implants and surgical instruments. The design of these coatings relies of a fundamental understanding of the intermolecular interactions involved ill the adhesion of proteins to surfaces. To get insight into these interactions, adhesion energies of glycine to pure and Si and N-doped (111) diamond surfaces represented as clusters were calculated ill the gas phase, using density functional theory (DFT) at the B3LYP/6-31G* level. The computed adhesion energies indicated that adhesion of glycine to diamond surface may be modified by introducing additional elements into the surface. The adhesion was also found to induce considerable change ill the conformation of glycine when compared with the lowest-energy conformer of the free molecule. In the Si and N-substituted diamond clusters, notable changes ill the structures involving the substituents atoms when compared with smaller parent molecules, such as 1-methyl-1-silaadamantane and 1-azaa-damantane, were detected. Adhesion free energy differences were estimated for a series of representative peptides (hydrophobic Phe-Gly-Phe, amphiphilic Arg-Gly-Phe, and hydrophilic Arg-Gly-Arg) to a (111) diamond surface substituted with different amounts of N, Si, or F, using molecular dynamics simulations ill ill explicit water environment employing a Dreiding force field. The calculations were ill agreement with the DFT results ill that adsorption of the studied peptides to diamond surface is influenced by introducing additional elements to the surface. It has been shown that, ill general, substitution will enhance electrostatic interactions between a surface and surrounding water, leading to a weaker adhesion of the studied peptides. (c) 2007 Wiley Periodicals, Inc.