Initial Graphite Disorder of Carbon Lattice Structures Increase Surface Hydrophilicity and Protein Adsorption

Abstract

Changes in wettability based on the dispersion properties of carbon nanotubes are generally achieved by chemical functionalization methods using acid treatments. Compared to a highly crystalline carbon structures (i.e., single-walled carbon nanotube and fullerene), low crystalline carbon structures (i.e., multi-wall carbon nanotubes and graphene) are easily functionalized in a water-based solution and exhibit excellent dispersity. However, to date, it has not been clear why low crystalline carbon structures exhibit superior dispersity relative to single-walled carbon nanotubes. In this study, we found that the initial crystallinity of the outer layers of a carbon lattice constitutes a significant material factor for determining further non-crystallization. As non-crystallized carbon lattice structures (corresponding to the D band in Raman analysis) initially increase, they can subsequently be further increased by means of ultra-sonication without any chemical treatment. Importantly, protein adsorption is more increased by reducing the surface crystallinity than a highly crystalline carbon lattice structure.