Adsorption of Albumin Fragments on Crystalline SWCNTs: How Surface Curvature Can Affect Protein Secondary Structure

Protein adsorption on biomaterial surfaces is a crucial step for biocompatibility. Albumin is the most abundant blood protein, and then this protein is important for biomaterials that will come into contact with blood. In previous work a theoretical study based on molecular mechanics (MM) and molecular dynamics (MD) methods is carried out at atomistic level to investigate the adsorption process of albumin A-subdomain on graphite surface and single-walled carbon nanotubes (SWCNTs) having different curvature. The aim of this work is to study the adsorption process of the albumin A-subdomain on four (10,10) SWCNTs in a crystalline arrangement in order to understand how the curvature of ordered nanotubes affects the adsorption process, providing also a simplified model of a rough surface at the nanometer level of a small crystalline domain. Interestingly, this soft albumin fragment having three alpha-helices in the native state, yields a short beta-sheets arrangement during the MD run. This finding suggests the importance not only of the rigidity of protein but also the curvature of the surface which can induce a secondary structure other than the native one. This theoretical work can be useful for investigating aspects that influence the conformation, then both the functionality of proteins adsorbed on CNT surfaces and their biocompatibility, and the favorable interactions interesting for NT solubilization to prepare reinforced composite materials.