Vibrational spectroscopic analysis of a metal/carbon nanotube coating interface and the effect of its interaction with albumin

Abstract

Multi-walled carbon nanotubes (MWCNTs) as a modifying phase on the titanium support can be potentially used for medical purposes as a material for the production of implants or implantable electrodes or for applications for cardiac surgery. Developing better blood compatible biomaterials must be connected with the condition of their anti-thrombogenic characteristic. A carbon nanotube layer was formed on a titanium plate coated in half with MWCNTs to have admission to: MWCNTs coating, to the Ti/MWCNTs interface region at the MWCNTs coating edge and finally to the Ti support. The Raman measurements were performed in two different locations: in the interface/edge region of the titanium and MWCNTs coating and in the center of the MWCNTs layer. For each of these positions, measurements in two different depths were performed: on the sample top surface of the MWCNT layer and near the bottom of the MWCNTs layer, i.e. at the titanium support interface. The studied sample regions differ in G-, D- and D′-mode structural characteristics as dispersion, crystallinity, the size of the arranged domains, and the distance between the point defects. The phase boundary region is more disordered and exposed to a greater surface tension. These features influence the interactions with albumin which represented the material behavior in contact with the tissue. The MWCNTs coating is hydrophilic (contact angle ∼55°), in the border area this value increases to ∼60°, then Ti support is hydrophobic (∼98°). Two dimensional correlation analysis allows us to unravel albumin-MWCNTs' interaction. The cross-peaks show a contribution from G+ and G− carbon nanotubes bands and protein secondary structure demonstrating the formation of a film on the surface of the test sample and indicate the change of the albumin conformation during adhesion.