Surface Topography Effects in Protein Adsorption on Nanostructured Carbon Allotropes

Abstract

We report a molecular dynamics (MD) simulation study of protein adsorption on the surface of nanosized carbon allotropes, namely single-walled carbon nanotubes (SWNT) considering both the convex outer surface and the concave inner surface, together with a graphene sheet for comparison. These systems are chosen to investigate the effect of the surface curvature on protein adsorption at the same surface chemistry, given by sp(2) carbon atoms in all cases. The simulations show that proteins do favorably interact with these hydrophobic surfaces, as previously found on graphite which has the same chemical nature. However, the main finding of the present study is that the adsorption strength does depend on the surface topography: in particular, it is slightly weaker on the outer convex surfaces of SWNT and is conversely enhanced on the inner concave SWNT surface, being therefore intermediate for flat graphene. We additionally find that oligopeptides may enter the cavity of common SWNT, provided their size is small enough and the tube diameter is large enough for both entropic and energetic reasons. Therefore, we suggest that proteins can effectively be used to solubilize in water single-walled (and by analogy also multiwalled) carbon nanotubes through adsorption on the outer surface, as indeed experimentally found, and to functionalize them after insertion of oligopeptides within the cavity of nanotubes of appropriate size.

Modeling and simulation of protein–surface interactions: achievements and challenges

“…They found tighter binding of the peptides on the larger C 180 . Raffaini & Ganazzoli (2013) showed that the binding strength of a protein to a carbon nanotube depends on the morphology and that the interaction energy between the protein and the nanoparticle was larger for the concave interior surface of the nanotube than for the convex outer surface. In a similar study, Chen et al (2009b) showed that the length and the diameter of CNTs affect the energetics of the interactions with a peptide drug.…”

Controlling Protein Adsorption through Nanostructured Polymeric Surfaces

“…[62][63][64] For example, theoretical studies of Gu et al and Raffaini and Ganazzoli have shed light on the effect of the surface curvature on the protein adsorption capacity. [65,66] Through the use of carbon nanotubes with various radii, and thus various local curvatures, they showed that protein adsorption becomes more prominent as the local curvature decreases. Experimental studies of Hammarin et al showed that the amount of adsorbed laminin per surface area is up to four times higher on 55 nm diameter gallium phosphide nanowires compared to the flat gallium phosphate surface.…”

Noncovalent Protein and Peptide Functionalization of Single-Walled Carbon Nanotubes for Biodelivery and Optical Sensing Applications

“…59 Overall, the interaction between the amino acids and graphene was found to be stronger than that for SWCNTs, suggesting that increased curvature disrupts the binding interaction. 60,61 These calculations have been supported by an observed monotonic decrease in BSA adsorption capacity with increasing nanomaterial curvature ( Figure 5). 62 In addition to noncovalent interactions between the biomolecule and nanotube, environmental conditions such as ionic strength and pH may also alter protein adsorption.…”