肝素化单壁碳纳米管的制备、表征及生物相容性

背景：碳纳米管具有独特的结构和理化性质，在药物载体、生物传感器及生物材料等领域应用前景广阔，但其疏水性强，易缠绕聚集，并且具有一定的细胞毒性，致生物相容性差。 目的：制备肝素化单壁碳纳米管，探讨表面肝素化对碳纳米管水溶性及生物相容性的影响。 方法：采用共价接枝的方法制备肝素化单壁碳纳米管，通过红外光谱进行表征；考察肝素化单壁碳纳米管在水溶液中的分散情况和稳定性；硫酸咔唑显色测定单壁碳纳米管表面的肝素多糖接枝量；测定抗Ⅹa 因子活性和活化部分凝血酶时间研究肝素化单壁碳纳米管的血液相容性，用MTT法研究10，20，40 mg/L肝素化单壁碳纳米管浸提液与小鼠骨髓干细胞的相容性。 结果与结论：肝素被成功接枝到单壁碳纳米管表面，肝素接枝量为257.53 mg/g；肝素化单壁碳纳米管在水溶液中分散良好，具有很好的悬浮稳定性；肝素化单壁碳纳米管抗Ⅹa因子活性为36.53 U/mg，具有明显的抗栓活性，能显著延长绵羊血浆活化部分凝血活酶时间，表现出显著的抗凝活性；肝素化单壁碳纳米管细胞毒性低，并对细胞增殖具有一定的促进作用。表明肝素化不仅能提高碳纳米管在水溶液中的分散性和稳定性，而且赋予其良好的血液相容性和细胞相容性。

Preparation,characterization and biocompatibility of heparinized single-walled carbon nanotubes

BACKGROUND：With unique structure and physicochemical property, carbon nanotubes have promising application prospects in the fields of drug delivery, biosensor and biomaterials. However, carbon nanotubes are highly hydrophobic and trend to aggregate, and thus carbon nanotubes are hard to be dispersed in solution. Furthermore, carbon nanotubes induce blood coagulation and have cytotoxicity, which greatly limit the application of carbon nanotubes.
OBJECTIVE：To prepare heparinized single-wal ed carbon nanotubes and to study the effects of heparin-immobilization on the water solubility, stability as wel as biocompatibility of carbon nanotubes.
METHODS：By the method of covalent grafting, heparinized single-wal ed carbon nanotubes was fabricated and characterized by Fourier transform infrared spectroscopy and carbazole assay. Transmission electron microscopy was used to investigate the dispersing performance and suspension stability of heparinized single-wal ed carbon nanotubes in aqueous solution. Anti-Xa activity and activated partial thromboplastin time assays were used to measure the anticoagulation activity of heparinized single-wal ed carbon nanotubes. MTT assay was used to evaluate the cytocompatibility of heparinized single-wal ed carbon nanotubes.
RESULTS AND CONCLUSION：Heparin was covalently linked to the surface of single-wal ed carbon nanotubes successfuly. The amount of heparin on single-wal ed carbon nanotubes was measured to be 257.53 mg/g. Heparinized single-wal ed carbon nanotubes were wel dispersed and stable in an aqueous solution without aggregation. The anti-Xa activity of heparinized single-wal ed carbon nanotubes was measured to be 36.53 U/mg, suggesting a significant anticoagulant activity. Further study of activated partial thromboplastin time assay found that the anticoagulant effect of heparinized single-waled carbon nanotubes could be prolonged. MTT assay revealed that heparinized single-wal ed carbon nanotubes had no cytotoxicity and showed good cytocompatibility. Taken together, the immobilization of heparin on single-wal ed carbon nanotubes wil not only improve its solubility and stability in water, but also endow it with excellent biocompatibility.