A significant improvement in cell and blood behaviors was observed in MWCNTs containing functional groups compared with pure MWCNTs. However, few reports are found to achieve MWCNT functionalization using the ion beam bombardment or ion implantation technique. The advantages of the physical method are its simplicity, small amounts of impurities, and high content of active groups on the surface of MWCNTs. Differing from the traditional chemical grafting, the ion implantation technique was also used to introduce find more NH2 and COOH groups onto MWCNTs, and graphene which was found to result in favorable

effects on their biocompatibility in our previous works [13–16]. To differ from traditional chemical grafting and ion implantation, in this paper, lower-energy N ion beam bombardment method was used to introduce N ions to MWCNTs. Compared with ion implantation, the advantages of low-energy ion beam bombardment are its

shallow injection depth and high content of active nitrogen on the surface of MWCNTs. The interaction between cell and substrates primarily occurred on the shallow surface of modified MWCNTs. The larger number of active nitrogen on the surface of MWCNTs which interacted with cells in vitro could increase the number of sites for cell growth. Thus, the modified MWCNT surface should have better bioactivity and biocompatibility. Due to length limitation, the comparison between pure and N+-bombarded MWCNTs in cytocompatibility and hemocompatibility will be

submitted AZD6244 supplier to other journals. This work only focused on the relationships between cell and blood behaviors and N atomic percentages of laboratory-made MWCNTs bombarded at different N+ beam currents (5, 10, and 15 mA), which were evaluated by cell adhesion, hemolysis, and platelet adsorption. Methods Synthesis MWCNTs were prepared using CVD system and then sprayed onto SiO2 substrates with air brush pistol. The detailed process of sample preparation can be found in our previous work [17, 18]. An ion beam-assisted deposition (IBAD) system (FJL560C12, SKY Technology Development Co., Ltd., China) was used to prepare N+-bombarded MWCNTs. This system has two ion sources, one CB-839 in vivo water-cooled sample holder and one water-cooled target holder. In this processing, the chamber Cyclin-dependent kinase 3 was evacuated to a base pressure lower than 3.0 × 10-4 Pa prior to N ion bombardment. Then, the high-purity N2 gas was introduced into low-energy ion source which could perform N ion bombardment to MWCNTs at desired ion bombarding parameters through computer controlling. N ion beams at ion beam currents of 5, 10, and 15 mA and a constant bombarding energy of 200 eV were respectively accelerated to bombard MWCNTs for 30 min to get three N atomic percentages of N+-bombarded MWCNT samples. The working gas pressure was 1.2 × 10-2 Pa.