學生：謝明修 指導教授：王振乾

Abstract 利用新穎的原位沉澱法合成 PLA 與 hydroxyapatite 、 chitosan 的均質奈米複合物，並探討其形態和特性。 Hydroxyapatite nanoparticles 分散於 CS-PLA 基材中 為棒狀形態，其長約為 300nm ，直徑為 50nm 。 探討有機基材與無機粒子間的作用和棒狀奈米粒 子的成型機制。

Introduction 天然骨架是一有機 - 無機奈米複合材料，由 hydroxyapatite (HA, Ca10(PO4)6(OH)2) 奈米晶粒和膠原纖維形成多層級 結構的組織。 Chitosan (CS) 為一天然生物降解性高分子，具有抗菌、生 物相容性和無毒之特性。然而，在潮濕環境下缺少骨結合 的生物活性、低的機械強度和結構鬆散限制其骨架組織工 程的應用。

Materials Chitosan was obtained from Nanxing Co. (Guangdong,China) with an 84% degree of deacetylation. Polylactic acid (Mw 200,000) was provided by the key laboratory of biomedical polymers of the Ministry of Education (Wuhan,China) Calcium nitrate tetrahydrate (Ca(NO3)24H2O), diammonium hydrogen phosphate ((NH4)2HPO4), glutaraldehyde, acetic acid, hydrochloric acid, 1,4-dioxane, sodium hypochlorite solution and ammonia were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China) and were all of analytical grade. All chemicals were used as received without any further purification. Deionized ultrapure water was used throughout the experiment.

Methods ： Synthesis of homogeneous CS– PLA/HA composites by in situ precipitation. 1.CS 溶於 40ml acetic acid 溶液 (2vol.%) ，攪拌至透明 2. Ca(NO3)2 ． 4H2O 和 (NH4)2HPO4 (Ca/P = 1.67) 3. PLA 溶解於 40 ℃, 40ml 的 1,4-dioxane 加入攪拌 至溶解 緩慢 加入 85 ℃，強力攪拌 1h ，使 1,4-dioxane 揮發 均質乳膠產物 0.1 ml glutaraldehyde (25 wt.%), as a crosslinker 持續攪拌至不透明，並存放於 ammonia solution ， 48h HA 於基材中漸漸地析出沉澱 浸泡於 ammonia ，之後再 以去離子水沖洗至 pH 約為 7 chemical reaction :

Methods ： Synthesis of homogeneous CS/HA composites by in situ precipitation. CS/HA composites with different weight ratios as control samples were also prepared by in situ precipitation. The procedures are the same as described in Synthesis of CS– PLA/HA composites, but without the addition of PLA.

Results and discussion FTIR spectra of (a) the CS–PLA/HA composite; (b) the inorganic phase of the CS–PLA/HA composite; and (c) the CS–PLA matrix of the CS–PLA/HA composite.

SEM micrographs of (a) the CS–PLA/HA composite (the inset shows the calibrated EDS area analysis of the composite); (b) a highly magnified SEM image of the CS–PLA/HA composite; (c) the CS/HA composite; and (d) a highly magnified SEM image of the CS/HA composite.

SEM micrographs of (a) the profile morphology of the CS–PLA/HA composite; (b) the inner structure of the inorganic block after calcining; (c) the surface of the remained CS–PLA matrix after removal of the inorganic phase; and (d) a highly magnified SEM image of the surface of the remaining CS–PLA matrix

Scheme of the formation mechanism of homogeneous inorganic/organic composites by in situ precipitation.

SEM micrographs of freeze-drying CS–PLA/HA composite: (a) primary pores; (b) sub-pores; (c) nanocomposites of sub-pores walls.

TEM micrographs of (a) inorganic precipitates isolated from the CS–PLA/HA composite through the oxidation procedure (the inset shows a polycrystal diffraction ring and diffused spots); (b) highly magnified TEM image of crystal lattice hydroxyapatite.

XRD pattern of (a) the CS–PLA/HA composite and (b) inorganic precipitates isolated from the CS–PLA/HA composite through the oxidation procedure.

Mechanical properties curves of CS–PLA/HA and CS/HA composite scaffolds: (a) compressive stress–strain curve with an organic/inorganic weight ratio of 50/50; (b) compressive stress–strain curve with an organic/inorganic weight ratio of 40/60;

Mechanical properties curves of CS–PLA/HA and CS/HA composite scaffolds: (c) compressive stress–strain curve with an organic/inorganic weight ratio of 30/70; (d) compressive stress–strain curve with an organic/inorganic weight ratio of 20/80;

Mechanical properties curves of CS–PLA/HA and CS/HA composite scaffolds: (e) elastic modulus–organic/inorganic ratio bar graph; (f) compressive strength–organic/inorganic ratio bar graph.

Conclusions 添加 PLA 於 CS 基材中，對成核和 HA 結晶成長有 很大的影響。 CS–PLA/HA 製備中， PLA 的 carboxyl 和 carbonyl groups 在 CS 水膠基材的三維網狀結構 和異質成核扮演著重要腳色。 HA 可改善 PLA 與 CS 生物高分子的彈性模數和壓 縮強度。