可溶性碳纳米管改性物的制备及其水凝胶载药性能的研究

【作者】 唐金春；

【导师】 黄可龙；

【作者基本信息】 中南大学 ， 制药工程， 2008， 硕士

【摘要】 碳纳米管(CNTs)自1991年被发现以来,由于其特有的力学、电学和化学特性以及独特的准一维管状分子结构,在许多高科技领域中具有许多潜在应用价值,迅速成为化学、物理学、材料科学以及生物医药领域的的研究热点。然而,CNTs呈化学惰性且不溶于常见的溶剂,这成为开展对其研究与应用的最大障碍,并且很多的研究表明CNTs的溶解性越好,其生物毒性越低。鉴于此,本研究利用生物大分子壳聚糖对碳纳米管进行表面改性和修饰处理,改善了碳管溶解性能。同时利用碳纳米管/壳聚糖复合物制备了新型的半互穿网络智能水凝胶,考察了其结构和性能。研究内容包括以下几方面:(1)采用两步微波辐射法,先以70%的浓硝酸氧化多壁碳纳米管,所得产物再与壳聚糖经酰胺化反应,制备多壁碳纳米管/壳聚糖复合物,两个反应可在1h内完成。实验通过两次调节反应液pH值并采用高速离心的方法,分离了未反应的氧化碳纳米管及壳聚糖原料,得到了纯碳纳米管/壳聚糖化合物。(2)采用红外光谱、紫外光谱对复合物结构进行了结构表征,并采用透射电镜观测了其形貌,采用热重分析方法研究了其热分解性能。结果表明:经过浓硝酸处理,碳纳米管表面产生了-COOH,C=O等含氧官能团;经过酰胺化反应,实现了壳聚糖在多壁碳纳米管上的共价接枝。(3)以戊二醛为交联剂,采用冷冻干燥的方法制备了一系列壳聚糖.碳纳米管/壳聚糖半互穿网络凝胶。测试了凝胶的机械性能,考察了凝胶在不同pH值缓冲溶液中的平衡水保留率和干凝胶的平衡溶胀率。实验结果表明,添加壳聚糖-碳纳米管复合物的凝胶与普通壳聚糖凝胶相比机械强度明显增加,并且保持了较好的pH敏感性。(4)对壳聚糖-碳纳米管/壳聚糖半互穿网络凝胶在不同条件下的溶胀动力学和退胀动力学进行了研究。结果表明,加入了CNT-CS后,智能水凝胶依然有很好的溶胀特性。其退胀性能与纯的CS凝胶一样也具有明显的pH敏感性,会在较低和较高pH缓冲溶液中的去溶胀率低,而在中性缓冲溶液中的去溶胀率高,而且不同的加入量对pH敏感性的影响不大。在酸性介质中,水凝胶扩散机理的特性指数n接近1,溶胀过程为Ⅱ迁移,而在其他三种介质中,水凝胶扩散机理的特性指数n在1和0.5之间,溶胀过程可用non-Fikcina扩散来描述。(5)以甲磺酸帕珠沙星为模型药物,对含有10%的壳聚糖-碳纳米管半互穿网络凝胶(C10)的释药性能与纯的壳聚糖水凝胶(C0)做了初步的对比研究。结果表明,所制备的凝胶的载药量都非常大。凝胶C0对药物的释放,在前期出现很明显的暴释现象;而凝胶C10的释放的比较缓慢、平稳,在体外释放的时间长达一周,有更好的缓释特性。更多还原

【Abstract】 Since their discovery in 1991,Carbon nanotubos（CNTs）have become the research focus in chemistry,physics,material science and biomedicine.CNTs have a lot of potential applications in the future Hi-Tech field due to their special mechanical,electronic,chemical properties and unique one-dimensional tube structures.However,CNTs are chemical inertia and cannot dissolve in general organic solvents, which hind their researches and applications.Moreover,it has been reported that CNTs’ toxicity could be reduced by improving their solubility.Here biomacromolecule chitosan was used to modify carbon nanotubes to improve their solubilities.CS-CNT/CS semi-IPN hydrogels were prepared and their structure and properties were studied.The main contents of this study are shown as follows:（1）CNT-CS was prepared by two steps through first oxidation of multiple-walled carbon nanotubes using 70%HNO₃ and then amidation of the oxidized products under microwave irradiation.The two processes could be completed in one hour.Purification of products was achieved by twice adjusting of pH value of the solution and centrifugation in succession,pure chitosan-grafted multiple-walled carbon nanotubes were obtained as final products.（2）The chemical structure of chitosan-grafted multiple-walled carbon nanotubes was characterized by IR and UV spectroscopy.Their morphology was characterized by transmission electron microscopy （TEM）,and the content of CS was analyzed by TGA.Results show that -COOH,C=O groups were successfully generated.Chitosan has been covalently grafted to the MWCNTs through the amide-acyl bonding.（3）A series of CS-CNT/CS semi-IPN hydrogels were prepared by a pre-freezing and freeze-drying technique sequentially using glutaraldehyde as a crosslinker.The mechanical properties of all hydrogels were tested.Equilibrium water retention and equilibrium swelling ratio of hydrogels was studied in the buffer solutions with different pH values.Contrast with the normal CS hydrogel,the mechanical strength of these semi-IPN hydrogels was remarkably improved,while the pH sensitivities were well preserved.（4）The swelling and deswelling kinetics of CS-CNT/CS semi-IPN hydrogels were studied.When CNT-CS composites were added into CS hydrogels,the swelling property and deswelling property of CS-CNT/CS semi-IPN hydrogels can be preserved well.Meanwhile,it showed excellent pH sensitivity as the the normal CS hydrogel.Deswelling ratios were lower in strong acid and strong alkaline buffer solutions than in neuter buffer solutions.The effect of the amount of CNT-CS on the pH sensitivity was not remarkable.Under acid conditions,the kinetic exponent of hydrogel approximate to 1 and the swelling mechanism isⅡstyle.The other kinetic exponent is between 1 and 0.5 and the transport mechanism belongs to non-fickian.（5）Comparing to normal hydrogels,CS-CNT/CS semi-IPN hydrogels containe 10%CS-CNT composites（C10）and can be used as drug delivery system for model drugs-PZFX.It was found that the loading ratio of hydrogels is huge.Drug releasing ability of hydrogels CO is beginning with a burst,while hydrogels C10 release drugs slowly.It is proved that hydrogels C10 could prolong drug releasing time up to one week.更多还原