【摘要】：本課題組利用殼聚糖的氨基在稀酸中陽離子化和再加堿溶液中和會凝膠化的特點制備三維有序殼聚糖支架。為了進一步的改進其強度、降解、穩(wěn)定性、以及羥基磷灰石的結晶性能等以滿足骨組織修復的需要。本文從不良溶劑對殼聚糖基體的影響方面出發(fā),對殼聚糖存在的三個狀態(tài)進行了研究：1)溶液態(tài)、2)凝膠態(tài)和3)支架態(tài)。 (1)首先研究了殼聚糖乙醇溶液的流變學性質。殼聚糖乙醇溶液隨著乙醇含量的增加,先是向牛頓流體轉變,而后又開始偏離牛頓流體,表現(xiàn)為流體指數(shù)的先增加后減小,這與粘度和凝膠點的變化一致。 (2)本文以殼聚糖和羥基磷灰石前軀體為原料采用了原位沉析法制備了殼聚糖/羥基磷灰石復合凝膠,并用乙醇和丙三醇對其進行了處理。支架的表面形貌變得粗糙,微孔增加,有大量的納米羥基磷灰石結晶(寬度為25～180nm,長度為50～500nm)分布于基體中。與未處理的支架相比,乙醇處理的支架孔徑降低、分布均勻；丙三醇處理的支架孔徑類似與未處理支架,隨羥基磷灰石的含量增加孔隙率卻增加,在濕態(tài)環(huán)境下的力學強度增強。而且處理過的兩種支架共同的特點是熱穩(wěn)定性降低,吸水率明顯提高,體外的降解速率降低,細胞生長增殖狀態(tài)良好。 (3)通過氫氧化鋰和尿素的混合溶液成功地制備一種具有自發(fā)形成凝膠的殼聚糖溶液。隨著殼聚糖溶液濃度和溫度的升高,這種趨勢越明顯,形成凝膠的時間越短。用6%硫酸溶液可誘導殼聚糖堿溶液快速凝膠,制備了具有明顯層狀結構和孔連通性優(yōu)良的支架,其表面具有凹凸起伏的粗糙形貌。通過模擬生物礦化,該支架表面生成了塊狀的羥基磷灰石結晶,具有促進成骨細胞在支架表面的粘附的作用和刺激細胞活性的特點。
[Abstract]:The objective of this study was to prepare three dimensional ordered chitosan scaffolds by using the characteristics of chitosan amino groups cationizing in dilute acid and neutralization of alkali-added solution. In order to further improve its strength, degradation, stability, and hydroxyapatite crystallization to meet the needs of bone tissue repair. In this paper, we studied the three states of chitosan: 1) solution state, 2) gel state and 3) scaffold state from the point of view of the influence of bad solvent on chitosan matrix. The main results are as follows: (1) the rheological properties of chitosan ethanol solution were studied. With the increase of ethanol content, the chitosan ethanol solution first changes to Newtonian fluid and then deviates from Newtonian fluid, which shows that the fluid index first increases and then decreases, which is consistent with the change of viscosity and gel point. (2) chitosan / hydroxyapatite composite gel was prepared by in situ precipitation from chitosan and hydroxyapatite precursor, and treated with ethanol and glycerol. The surface morphology of the scaffold became rough and the micropores increased. A large number of nano-hydroxyapatite crystals (width 25 ~ 180nm, length 50~500nm) were distributed in the matrix. Compared with the untreated scaffolds, the pore size of ethanol treated scaffolds was decreased and distributed evenly. The pore size of the scaffolds treated with glycerol is similar to that of the untreated scaffolds, but the porosity increases with the increase of hydroxyapatite content, and the mechanical strength increases in wet environment. The common characteristics of the two scaffolds were the decrease of thermal stability, the increase of water absorption, the decrease of degradation rate in vitro, and the good state of cell growth and proliferation. (3) A chitosan solution with spontaneous gel formation was successfully prepared by the mixture of lithium hydroxide and urea. With the increase of chitosan concentration and temperature, this trend is more obvious and the time of gel formation is shorter. Chitosan alkali solution was induced by 6% sulfuric acid solution, and the scaffold with obvious layered structure and good pore connectivity was prepared. The surface of the scaffold was rough with ups and downs. By simulating biomineralization, massive hydroxyapatite crystals were formed on the surface of the scaffold, which promoted the adhesion of osteoblasts to the scaffold surface and stimulated cell activity.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：R318.08

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