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 co

mposites by in situ precipitation. • CS/HA composites with different weight ratios as control sam

ples 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 theCS–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。