學生：謝明修指導教授：王振乾

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 0.1 ml glutaraldehyde (25 wt.%) , as a crosslinker 均質乳膠產物持續攪拌至不透明，並存放於 ammonia solution，48h chemical reaction: 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

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 arethe 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。

學生：謝明修 指導教授：王振乾