The Research In Biomedical Properties Of COOH~+Implantation-Modified Multi-Walled Carbon Nanotubes

Ion implantation was applied to modify the surface of multi-walled carbon nanotubes (MWCNTs). The COOH+implantation was performed for MWCNTs in two ion doses, and then they were tested in biomedical assays, in order to insight into how COOH+implantation affected the biocompatibility of the MWCNTs. The ion doses were3×1014and1×1015ions/cm2, respectively. Transmission electron microscope (TEM), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) was applied to characterize pristine MWCNTs and COOH+implantation-modified MWCNTs (COOH/MWCNTs) in two ion doses. The results demonstrated that all the MWCNTs had a similar tubular structure and carboxyl groups existed on the surface of COOH/MWCNTs. Water contact-angle assays showed that the surface of COOH/MWCNTs became more hydrophilic compared with pristine MWCNTs.For investigate the cytocompatibility and hemocompatibility of MWCNTs and COOH/MWCNTs, cell and blood assays were performed. In cell assays, two kinds of cells, mouse-fibroblast cells (L929) and human endothelial cells (EAhy926), were used to assess the cytocompatibility of three MWCNTs systems. Trypan blue dye assays were used to count cell numbers after different incubation days in order to confirm the effect of various MWCNTs on the proliferation of both mouse-fibroblast and endothelial cells. At the same time, SEM was employed to observe cell morphology. The results of cell assays and SEM showed that both COOH/MWCNTs displayed the improved cell adhesion, proliferation and viability, indicating their superior cytocompatibility over pristine MWCNTs.From platelet-adhesion assays, compared with pristine MWCNTs, the platelet-adhesion rates of COOH/MWCNTs sharply decreased and as the ion dose increased, the platelet-adhesion rate of COOH/MWCNTs reduced. SEM images indicated that the numbers and activation of platelets fixed on pristine MWCNTs was much higher than COOH/MWCNTs. These results meant that the functional carboxyl groups improved the anticoagulant capacity of COOH/MWCNTs obviously. In hemolytic rate assays, all the pristine MWCNTs and COOH/MWCNTs were nonhemolytic.