Interactions of boron nitride nanosheet with amino acids of diferential polarity

Abstract

Free amino acids represent a category of diferent biomolecules in the blood plasma, which bond together to make up larger organic molecules such as peptides and proteins. Their interactions with biocompatible nanoparticles are especially important for plasma-related biomedical applications. Among the various nanomaterials, the applications of carbon and boron nitride-based nanotubes/ nanosheets have shown a huge increase in recent years. The efect of molecular polarity on the interaction between a boron nitride nanosheet (BNNS) and amino acids is investigated with quantum mechanical calculations by density functional theory (DFT), classical MD simulations, and welltempered metadynamics simulations. Four representative amino acids, namely, alanine (Ala), a nonpolar amino acid, and aspartic acid (Asp), lysine (Lys) and serine (Ser), three polar amino acids are considered for their interactions with BNNS. In DFT calculations, the values of the adsorption energies for Lys-BNNS and Ser-BNNS complexes are− 48.32 and− 32.89 kJ/mol, respectively, which are more stable than the other cases. Besides, the adsorption energy calculated confrms the exergonic reactions for all investigated systems; it implied that the interaction is favorable electronically. The MD results show that the LYS molecules have a higher attraction toward BNNS because of its alkane tail in its side chain, and the ASP revealed the repulsion force originating from its COO– group. All the results are confrmed by free energy analyzes in which the LYS showed the highest adsorption free energy at a relatively farther distance than other complexes. In fact, our results revealed the contribution of functional groups and backbone of the amino acids in the adsorption or repulsion features of the studied systems.