The detailed measurement process can be found in our previous work [17–19]. Characterization by X-ray photoelectron spectroscopy MLN2238 mw (XPS) (PHI5000 VersaProbe system, Physical Electronics, Chanhassen, MN, USA) was used to prove the existence of the main functional groups in the three samples. The morphology of N+-bombarded MWCNTs was examined with a field GS-4997 cost emission scanning electron microscope (FESEM; 18SI, FEI, Hillsboro, OR, USA) operated at 10.0 kV and a field emission scanning electron microscope (SU8020, HITACHI,

Tokyo, Japan) operated at 1.0 kV. The detailed morphologies and chemical bonding states of the samples were characterized using a JOEL JEM 2100 transmission electron microscope (TEM; Tokyo, Japan) and Renishaw micro-Raman 2000 system (Wotton-under-Edge, UK) and a 514-nm laser line excitation. Cell adhesion assays The human endothelial cell line EAHY926 and mouse fibroblast cells (L929) were used to investigate the cytocompatibility of N+-bombarded MWCNTs. The processes of cell culture and cell vaccination can be found in our previous work [13–16]. Endothelial cells were harvested from

the cultures and replaced into 24-well plate (5 × 104 cells/ml) in four groups (three kinds of N+-bombarded MWCNTs and blank control group). The inoculum density of fibroblast cells is 2.5 × 104 cells/ml. After 1 to 7 days in an incubator (culture intervals of 0.5, 1, 2, 3, 5, and 7 days), the medium was removed,

and the cell monolayer was washed several selleck times with PBS and then isolated by trypsin for enumeration. Immunofluorescence staining was done as CHIR 99021 described with mouse monoclonal anti-α-tubulin (clone B-5-1-2, 1:1,000 dilution; Sigma, St. Louis, MO, USA), followed by 1:200 dilution of various fluorochrome-conjugated secondary antibodies. Finally, DNA was stained with DAPI (1 μg/ml) for 5 min. For immunostaining, mouse fibroblast cells were grown on three kinds of N+-bombarded MWCNTs at 2.5 × 104 cells/ml for 24 h. Confocal scanning laser microscopy (CSLM) (Nikon Eclipse 90, Shinjuku, Tokyo, Japan) was employed to observe cell morphology and stretching on the three samples. The scanning electron microscope (SEM) (FEI QUANTA 200) was employed to observe endothelial cells’ and mouse fibroblast cells’ morphology and stretching on three materials. Hematotoxicity analysis Platelet adhesion test was conducted to evaluate the surface thrombogenicity of the materials in vitro. Blood taken from a healthy rabbit with potassium oxalate as the anticoagulant was centrifuged about 15 min and converted to platelet-rich plasma (PRP). All the N+-bombarded MWCNTs and reference groups were cleaned and then incubated in human PRP for 30 min at 37°C. The detailed process can be found in our previous work [17, 18].