Study On The Synthesis And Drug Loading Of Carbon Nanotubes/hydroxyapatite In Situ Composite Powders

Carbon nanotubes(CNTs) have become a new kind of drug carrier and showed the potential applications in biological medicine field because of its high drug loading, good cell penetrating ability and strong target characteristics. But the CNTs without modification have a lot of shortcomings, such as strong surface hydrophobicity, agglomeration,cytotoxicity and so on, which limit their applications as drug carrier.According to the improvement demand for CNTs as drug carrier,CNTs(Fe)/hydroxyapatite(HA) magnetic targeting drug carriers were designed and prepared. The processes to synthesize CNTs/HA in-situ composite structures using transition metal catalysts by chemical vapor deposition(CVD) were studied. The cytotoxicity, modification processes and patterns of drug loading and release of the in-situ composite powder were investigated.Based on the preparation of Fe(Co and Ni)/HA catalysts by the deposition-precipitation method, CNTs/HA composite powder was synthesized by in-situ CVD method using methane as the carbon source and argon as carrier gas. The influences of technical conditions, including the type of catalyst, synthesis temperature and catalyst content, on the synthesis effect of CNTs were investigated. The results showed that, under the conditions of5 wt.% Fe and 700°C, the prepared CNTs/HA composite powder dispersed evenly,possessed high yield and had good graphitization degree and thermal stability.The cytotoxicity of the CNTs(Fe)/HA, CNTs(Ni)/HA and commercial CNTs were studied by the method of MTT. The results showed that, CNTs(Ni)/HA and commercial CNTs had certain cell toxicity because the cultured cells appeared large deformation retraction and the number of living cells decreased. But the CNTs(Fe)/HA had no obvious cytotoxicity and was suitable to be used as drug carrier for the cultured cells forming normally and growing abundantly.On the premise of the functional treatments for CNTs(Fe)/HA, the magnetic targeting drug carriers, DOX-FA-CHI-CNTs(Fe)/HA, was developed. In addition, the drug loading and releasing rates were researched. The result indicated that, the CNTs became shorter,had less impurity and dispersed homogeneously after acid treatment. Moreover, CHI, FA and DOX were successfully loaded onto the surface of CNTs and the average drugloading rate was 130%. The drug was released successfully in the PBS of pH=5.5, while the drug released little under the PBS of pH=7.4 and the release quantity changed little with time. It’s worth mentioning that CNTs(Fe)/HA had good magnetic properties before and after drug loading, which made it possible to transport drug under the action of magnetic field.