201221157 六、發明說明： 【發明所屬之技術領域】 本發明係關於-種製備用作生物可降解支架之複合物或 多孔複合物之方法，及其製備之複合物與該複合物之用 途。詳言之，該複合物為硫酸鈣（cs)_聚乳酸（PLA)複合物 或多孔複合物，且該複合物可特別用作原位成孔之支架。 • 【先前技術】 、 月折、遺傳性畸形、腫瘤及脊椎手術之骨缺損治療通常 需要植入移植物。典型的可吸收組織工程支架應具有充足 孔隙率使骨細胞及血管向内生長。確定組織與器官成功再 生之重要因素包括表面化學性質、孔隙率、孔隙微觀結構 與宏觀結構及支架形狀。 美國公開案第200300555 12號提供一種可注射且可塑之 骨水泥’其包含生物可降解鈣基化合物，該等化合物包括 硫酸4弓、經基填灰石及填酸三弼。然而，該專利申請宰沒 有提供生物可吸收性支架。 WO 2005/105170係關於骨替代組合物及使用方法。在一 較佳實施例中’該組合物包含無水硫酸妈、二水合硫酸弼 及聚乙二醇（PEG)。CN 1724081 A提供一種具有聚合物之 複合多孔硫酸鈣支架，其中藉由將聚乳酸或乳酸/醇酸共 聚物或多元醇酸或聚己内酯或聚經基丁酸酯或聚經基丁酸 酯共聚物或聚酸酐溶解於氣仿中，攪拌，按比例將其與硫 酸鈣混合，倒入鑄模中且乾燥來製備該複合物。US 2002018797 (A1)係關於一種在組成及微觀結構方面模擬天 143659.doc 201221157 然骨之奈米級磷酸鈣/膠原蛋白複合物，以及由該複合物 與聚（乳酸）(PLA)或聚（乳酸共乙醇酸xpLGA)之複合物製成 的多孔骨替代品及組織工程支架^ US 200828143 1提供可 修復人類或動物個體骨骼中之缺損的陶瓷材料，其包含具 有生物可吸收性塗層之多孔陶瓷支架及包含變性去礦質骨 之載體。此種陶瓷可含有選自由羥基磷灰石、磷酸三弼、 _酸好、碳酸辦、硫酸齊及其組合組成之群的材料。然 而，上述先前技術中之支架沒有提供足夠的壓縮應力抗 性。 為達最佳之骨再生能力’最好作為骨傳導基質者為具有 二維（3 -D)結構之多孔支架。由於其海綿狀結構，多孔支 架在骨缺損治療初期通常無法承受很多生理負荷。在承受 負荷情況下’多孔支架傾向於變形且喪失孔隙結構，因此 可能不利於處在壓力下但仍需保持空間之某些臨床應用。 舉例而a ’椎間融合護架（interbody fusion cage)，一種脊 椎融合程序中所用之人工替代物，應具有足夠的力學穩定 性以支撐及轉移負荷以便保持椎間孔高度。 因此’臨床仍需要研發在移植初期具有適當的力學性質 之生物可吸收性複合物。將複合物嵌入骨缺損處後，藉由 體内降解原位形成複合物支架之多孔結構。 【發明内容】 本發明之一目的為提供一種製備包含硫酸鈣與聚乳酸之 複合物的方法，其包含以下步驟： (a)使選自二水硫酸鈣、α-半水硫酸鈣或β-半水合硫酸 143659.doc 201221157 鈣或其混合物之硫酸鈣脫水以獲得無水硫酸鈣；及 (b)在高溫下熔融聚乳酸，且將熔融聚乳酸與無水硫酸 鈣混合以形成硫酸鈣-聚乳酸複合物； 其中聚乳酸與硫酸鈣之比率在約8〇%_5〇% (w/w)至約 20%-50% (w/w)範圍内。 本發明之另一目的為提供一種藉由本發明之方法製備的 複合物》亦提供一種包含選自二水硫酸鈣、α_半水硫酸鈣 或β-半水硫酸鈣或其混合物之硫酸鈣與聚乳酸的複合物， 其中聚乳酸與硫酸鈣之比率在約80%_50% (w/w)比約2〇0/〇· 5 0% (w/w)範圍内》 本發明之另一目的為提供一種原位形成多孔支架之方 法’其包含將本發明之複合物嵌入骨缺損處，且體内降解 該複合物以形成多孔支架。 另一目的為提供一種製備包含硫酸鈣與聚乳酸之多孔複 合物的方法，其包含以下步驟： Ο)使選自二水硫酸鈣、α_半水硫酸鈣或β_半水硫酸鈣 或其混合物之硫酸鈣脫水以獲得無水硫酸鈣； (b)在高溫下熔融聚乳酸，且將熔融聚乳酸與無水硫酸 鈣混合以形成鈣-聚乳酸複合物；及 (e)對該鈣-聚乳酸複合物進行顆粒溶洗以形成具有互連 孔隙之多孔複合物； 其中聚乳酸與硫酸鈣之比率在約80%-50% (w/w)比約 20%-50% (w/w)範圍内，且互連孔隙之孔隙尺寸在1〇〇至 500 μιη範圍内。 I43659.doc 201221157 另目的為提供-種藉由本發明之方法製備的多孔複合 物。亦提供-種包含選自二水合硫酸軒、…半水合硫_ 或β-半水合硫_或其混合物之硫酸舞與聚乳酸的多孔複 合物，其中聚乳酸與硫酸約之比率在約8〇%-5〇% 比 約20〇/。德（w/w)範圍内，且其中孔隙為互連的且孔隙尺 寸在100至500 μπι範圍内。 【實施方式】 本發明提供一種製備硫酸鈣_聚乳酸複合物之方法。由 特定比率範圍之硫酸鈣與聚乳酸製備的具有更有更佳力學 性質的多孔複合物。舉例而言，其顯示高降服強度及揚氏 模數（Young’s modulus)。由於其力學性質良好，該複合物 可作為原位成孔椎間盤植入物架。 本文所用之「巨觀孔隙」（macr〇p〇re)係指聚合物支架内 由聚合物壁所構成的空隙。 「互連」（interconnecti〇n)係指將巨觀孔隙彼此連接之流 動通道。互連物包含將上文定義之所有材料中穿孔之巨孔 互連（通道）、微孔互連（通道）及奈米孔隙。 材料之「降服強度」（yield strength)在工程及材料科學 中被定義為材料開始塑性變形時之應力。在降服點之前， 材料係彈性變形’且當移除施加之應力時將恢復其原樣。 一旦超過降服點，一些部分將為永久且不可逆的變形。 「 抗壓強度」（compressive strength)係指材料财受軸向 定向推力之能力。 「楊氏模數」（Young's modulus)係指描述材料硬度之材 143659.doc -6- 201221157 ^生質因此為卫程設計中最重要的 — 數亦稱為拉伸模數，其A^ 杨氏模 许甘 其為各向同性彈性材料之硬,度的量 二、破定義為單轴向應力與單軸向應變在虎克定律 ::SLaW)控制之應力範圍内之比率。此比率可自對材 =本進行之拉伸測試期間建立之應力應變曲線的斜率 以實驗方法確定。 生物可降解」 生物的作用或是自 作用。 (biodegradable)意謂藉由活體内細胞之 然水解後能夠分解為易於代謝的產物之 植體」（ — ant)及其類似術語指示在例如疾病、損傷 或創傷之醫學治療過程中置放外來物質在患者身體中。 術語「骨缺損」（b〇ne defect)係指任何骨缺損區域，諸 如骨中之空隙、裂隙…或其他不連續。例如，骨缺損 可為天生地;^成或由疾病或外傷如:病理性、，务炎性或腫 瘤疾病所引起。 製備包含硫酸联聚乳酸之複合物之方法及自其製備之複 合物 在心樣中，本發明提供一種製備包含硫酸鈣與聚乳酸 之複合物的方法，其包含以下步驟： (a) 使選自二水硫酸鈣、α_半水硫酸鈣或卜半水硫酸鈣 或其混合物之硫酸鈣脫水以獲得無水硫酸鈣；及 (b) 在冏/皿下熔融聚乳酸，且將熔融聚乳酸與無水硫酸 鈣混合以形成鈣-聚乳酸複合物； 其中聚乳酸與硫酸鈣之比率在約8〇%_5〇% (w/w)比約 143659.doc 201221157 20%-50% (w/w)範圍内。 在本發明方法的步驟（a)中，將硫酸弼脫水以獲得無水硫 酸弼。該脫水步驟係用於減少本發明方法中的水的不良影 響。在炫融聚乳酸之過程中，水的存在將會破壞分子間醋 鍵而引起聚乳酸之裂解。因此，過程中之高水含量將引起 聚乳酸降解且降低複合物之強度。可使用不同形式之硫酸 鈣控制無水硫酸鈣之晶形與尺寸。根據本發明，硫酸妈可 為二水硫酸約、α_半水硫酸釣或β_半水硫酸辦或其混合 物。硫酸弼較佳為β -半水硫酸釣。 在本發明之步驟（b)中，在高溫下溶融聚乳酸且接著將 其與無水硫酸約混合以形成約-聚乳酸複合物，其中聚乳 酸與硫酸在弓之比率在約80%-50% (w/w)比約20%-5 〇% (vv/w) 範圍内。聚乳酸與硫酸鈣之比率較佳在約75%-50% (w/w〇 比約 25%-50% (w/w)、約 75%-5 5% (w/w)比約 25%-40% (w/w)、約 75%-60% (w/w)比約 25%-45。/〇 (w/w)或約 750/〇- 65% (w/w)比約25%-35% (w/w)之範圍内。聚乳酸與硫酸約 之比率更佳為70%比30% (w/w) » 熔融聚乳酸之溫度在此項技術中為已知的。高溫較佳在 約120°C至約300°C之範圍内。高溫較佳在約15〇。(：至約 300t：、約 15〇°C 至約 280°C、約 150°C 至約 250°C、約 180°C 至約30(TC、約180°C至約280°C、約180°C至約25〇t或約 200°C至約250°C之範圍内。高溫更佳在約200°C至約250°C 之範圍内。 在另一態樣中，本發明提供一種藉由本發明之方法製備 143659.doc 201221157 的複合物。本發明之複合物包含選自二水硫酸妈、α-半水 硫酸鈣或β-半水硫酸約或其混合物之硫酸鈣與聚乳酸，其 中聚乳酸與硫酸鈣之比率在約80%-50% (w/w)比約20%-50% (w/w)範圍内。聚乳酸與硫酸鈣之比率較佳在約75〇/〇_ 50% (w/w)比約 25%-50% (w/w)、約 75%-55% (w/w)比約 25%-40% (w/w)、約 75%-60% (w/w)比約 25%-45% (w/w)或 約75%-65% (w/w)比約25%-35。/〇 (w/w)之範圍内。聚乳酸與 硫酸鈣之比率更佳為70%比30% (w/w)。根據本發明，硫酸 鈣較佳為β-半水硫酸鈣。 本發明之複合物具有足以長期保持骨缺損區穩定性之初 始力學性質。本發明之複合物為生物可降解的且具有高降 服強度及揚氏模數《因此，該複合物具有適合之力學性質 以允許形成新骨骼。此外，該複合物具有比聚乳酸高的降 解速率，因此，可為新骨骼之生長提供更大空間進而提高 骨融合之穩定性。 原位形成多孔支架之方法 在另態樣中，本發明亦提供一種原位形成多孔支架之 方法，其包含將本發明之複合物嵌入骨缺損處並藉由體内 降解該複合物以形成多孔支架。在-實施例中，多孔支架 為脊椎椎體瘦架。移植本發明之複合物係使用骨路修復或 置換之心準外科技術。可直接將複合物移植至需要骨路生 長之4位。在較佳實施例中’將複合物預缚成所要形狀以 t H台療之骨絡缺^。複合物之初&強度足夠維持移 植初始階段之應力。移植很長時間後’由於聚乳酸與硫酸 143659.doc 201221157 鈣之不同降解速率，該複合物即會形成具有多種孔隙尺寸 (包括巨觀孔隙、微觀孔隙及奈米孔隙）之多孔構型且該等 孔隙為互連的結構。因此’原位孔隙形成之PLA/CS支架 系統之目的在於提供癒合初期階段之力學穩定性。其後， 自硫酸鈣溶解釋放之鈣離子與所形成之孔隙結構提供進一 步有利的條件，使骨細胞及血管向内生長。 製備包含硫酸舞與聚乳酸之多孔複合物的方法及自其製備 之多孔複合物 在另一態樣中，本發明提供一種製備包含硫酸約與聚乳 酸之多孔複合物的方法，其包含以下步驟： (a) 使選自二水硫酸鈣、α-半水硫酸鈣或β_半水硫酸鈣 或其混合物之硫酸鈣脫水以獲得無水硫酸弼； (b) 在高溫下熔融聚乳酸，且將熔融聚乳酸與無水硫酸 鈣混合以形成鈣-聚乳酸複合物；及 (c) 對該約-聚乳酸複合物進行顆粒溶洗以形成具有互連 孔隙之多孔複合物； 其中聚乳酸與硫酸鈣之比率在約80%-50% (w/w)比約 20%-50% (w/w)範圍内，且互連孔隙之孔隙尺寸在1〇〇至 500 μηι範圍内。 步驟（a)與步驟（b)及其實施例與彼等在製備包含硫酸鈣 與聚乳酸之複合物的方法中所提及者一致，其中聚乳酸與 硫酸鈣之比率在約80%-50〇/〇 (w/w)比約20%-50% (w/w)範圍 内。聚乳酸與硫酸鈣之比率較佳在约75%·5〇% (w/w)比約 25〇/〇-50% (w/w)、約 75%-550/〇 (w/w)比約 25%-40% (w/w)、 143659.doc •10- 201221157 ^75%-60〇/〇 (w/w)tb ^250/0-450/0 (w/w)，t^75%-65% (w/w) 比約25%-35% (w/w)i範圍内。聚乳酸與硫酸鈣之比率更 佳為70%比30% (w/w)。關於步驟（〇,對鈣-聚乳酸複合物 進行顆粒溶洗以形成具有互連孔隙之多孔複合物。顆粒溶 洗技術已廣泛用於製造3D多孔支架以供組織工程應用。簡 s之，顆粒溶洗涉及在溶劑中製造聚合複合物之懸浮液。 較佳溶劑為水，最佳為蒸餾去離子水，其在處理所需之時 間内不會/谷解聚合物或引起明顯地聚合物水解。研磨致孔 劑顆粒（諸如鹽（salt)、明膠或含蠟烴顆粒）且篩分成小顆 粒，且將彼等具有所要尺寸之顆粒轉移至鑄模中。接著將 聚合物懸浮液澆鑄於致孔劑填充之鑄模中◊接著藉由在大 亂下及/或真空中蒸發來移除溶劑。溶劑蒸發後，藉由在 水中浸沒濾除致孔劑晶體以形成多孔結構。 根據本發明，多孔複合物之互連孔隙的孔隙尺寸在100 至500 μιη範圍内。孔隙尺寸較佳在15〇至45〇 μιη或2〇〇至 400 μηι範圍内。在一本發明之較佳實施例中，氣化鈉 (NaCl)用作致孔劑且在步驟（c)之顆粒溶洗中剩餘NaCi之濃 度低於10 ppm。 在另一態樣中，本發明提供一種藉由本發明之方法製備 的多孔複合物。本發明之多孔複合物包含選自二水合硫酸 鈣、α-半水硫酸鈣或β_半水硫酸鈣或其混合物之硫酸鈣與 聚乳酸，其中聚乳酸與硫酸鈣之比率在約8〇% 5〇% (w/w) 比約20%-50% (w/w)範圍内，且其中孔隙為互連的且孔隙 之尺寸在100至500 μιη範圍内。聚乳酸與硫酸鈣之比率較 143659.doc 201221157 佳在約 75%-50% (w/w)比約 25°/〇-50% (w/w)、約 75%-55% (w/w)比約 25°/〇-40% (w/w)、約 75%-60% (w/w)比約 25%-45% (w/w)或約 75%-65。/〇 (w/w)比約 25%-35% (w/w)之範圍 内。聚乳酸與硫酸鈣之比率更佳為70%比30% (w/w)。孔隙 尺寸較佳在150至45 0 μιη或200至400 μηι範圍内。根據本發 明，硫酸鈣較佳為β-半水硫酸鈣。 複合物可具有多孔結構，其降低複合物之初始極限壓縮 應力且提高複合物之降解速率。令人訝異的，本發明之多 孔複合物提供更高之細胞黏著速率，且在複合物中培養之 細胞具有更高鹼性磷酸酶活性及更高骨橋蛋白 (osteopontin，ΟΡΝ)與骨延蛋白（bone sialoprotein，BSP) mRNA表現。 實例 實例1 製備本發明之複合物 藉由乾燥對聚乳酸與β-半水硫酸鈣進行脫水。將聚乳酸 置放於烘箱中且在約50°C之溫度下乾燥2天。β-半水硫酸 鈣在約50(TC之溫度下乾燥1小時，接著移至烘箱中且在 50°C下乾燥2天。藉由加熱熔融乾燥之聚乳酸，將乾燥之 β-半水硫酸鈣按20%比80%、30%比70°/。或40°/。比60°/。之比 率添加至熔融聚乳酸中，且在約220°C之溫度下混合以獲 得本發明之複合物。 實例2 製備本發明之多孔複合物 使用實例1中獲得之包含比率為約70%比約30%的聚乳酸 與β-半水硫酸鈣的複合物來製備本發明之多孔複合物。將 143659.doc 201221157 實例1之複合物加熱至約220〇c，接著向其添加NaC卜將所 得多孔複合物填充入圓形鑄模中，接著冷卻至室溫。以 ll〇°C加熱冷卻之多孔複合物持續4小時’接著冷卻至室 溫。自鑄模取出所得多孔複合物且用砂紙摩擦複合物表 面°隨後’在蒸餾水中浸沒多孔複合物以移除NaC卜將所 得多扎複合物於烘箱中以約50°c之溫度下乾燥1天。 實例3本發明之複合物的抗壓強度測試 藉由使用液壓式材料試驗機，根據抗壓強度測試標準之 ASTMD695量測抗壓強度。對如實例i所提及製備的包含 比率為20%比80%、30。/。比70°/。或40%比60。/。之β-半水硫酸 約與聚乳酸的複合物進行抗壓強度測試。在〇、1及3個月 時對包含比率為30°/。比70%之β-半水硫酸鈣與聚乳酸的複 合物進一步進行抗壓強度測試。圖1(Α)與（Β)展示具有比 率為20°/。比80%、30%比70%或40°/。比60%之β-半水硫酸飼 與聚乳酸的複合物的壓縮應力（Α)與揚氏模數（Β)。上述複 合物展現有利的壓縮應力。圖2(Α)與展示一個月後， 壓縮應力（Α)與揚氏模數（Β)無顯著變化，因此本發明之複 合物可保持至少一個月之穩定性（ρ :聚乳酸複合物；PC : 實例1之包含比率為30%比70%之β-半水硫酸鈣與聚乳酸的 複合物）。3個月後，儘管複合物已發生降解，但其仍保持 可接受之應力。 對實例2中製備之多孔複合物在〇至3個月期間進行抗壓 強度測試《圖3(A)與（Β)展示在〇至3個月期間之壓縮應力 (Α)與揚氏模數（Β)(ρΡ :多孔聚乳酸；pPC :實例2之多孔 143659.doc 13 201221157 複合物）。1個月後，實例2之多孔複合物的壓縮應力與揚 氏模數無顯著變化，因此本發明之多孔複合物可保持至少 一個月之穩定性。3個月後，儘管複合物展現降解，但其 仍保持可接受之應力。 實例4本發明之複合物與多孔複合物中接種的成骨細胞 中之骨橋蛋白（ΟΡΝ)及骨唾液酸蛋白（BSP)之信息核糖核酸 (mRNA)的表現量 將自2曰齡史博格多利大鼠（Sprague Da wley rat)之顱骨 獲得之成骨細胞接種且附著於實例1之複合物與實例2之多 孔複合物。用含有50 pg/ml之L-抗壞血酸2-峨酸酯、1 〇 mM β-甘油磷酸酯及1〇% FBS的α-ΜΕΜ培養該等細胞3週。 根據製造商說明書使用QIAGEN RNeasy®微型套組（目錄號 74104 ; QIAGEN，CA，U.S.A.)來量測實例1之複合物與實 例2之多孔複合物中的細胞之ορΝ與BSP之mRNA的表現 量。圖4展示本發明之複合物與多孔複合物中培養之成骨 細胞展現OPN mRNA及BSP mRNA之高表現量（P:聚乳酸 複合物；pP :多孔聚乳酸；PC :實例1之包含比率為3〇0/〇 比70%之β-半水硫酸鈣與聚乳酸的複合物；ppc :實例2之 多孔複合物；B :黑色；wi :第1週；W2 :第2週；W3 : 第3週）。 實例5原位形成多孔支架之方法 在蘭峨豬（Lanyu pig)之下頜骨中穿鑿28 3 mm2之缺損。 將聚乳酸複合物之支架與實例1之β_半水硫酸鈣與聚乳酸 之複合物的支架分別植入缺損處。8週後’由x-射線照片 143659.doc 201221157 之結果可見（參見圖5)，植入聚乳酸支架之缺損之尺寸減小 至16.3±2.0 mm2，而植入聚乳酸及硫酸鈣支架之缺損之尺 寸減小至8.3土0.9 mm2。顯然，實例1之複合物相對於聚乳 酸支架，產生超乎預期之功效。 【圖式簡單說明】 圖1(A)與（B)顳示具有比率為20%比80%、30%比70%或 ' 40%比60%之β-半水硫酸鈣與聚乳酸之複合物的壓縮應力 - (Α)與揚氏模數（B); 圖2(A)與（Β)展示在3個月期間具有比率為30%比70%之β-半水硫酸鈣與聚乳酸之複合物的壓縮應力（Α)與揚氏模數 (B); 圖3(A)與（B)展示在0至3個月期間之壓縮應力（A)與楊氏 模數（B); 圖4展示本發明之複合物與多孔複合物令培養之成骨細 胞展現OPNmRNA及BSPmRNA之高表現量；及 圖5展示植入聚乳酸與硫酸鈣支架之缺損之尺寸的減 143659.doc •15·201221157 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method of preparing a composite or porous composite for use as a biodegradable stent, and a composite thereof and its use. In particular, the composite is a calcium sulfate (cs)-polylactic acid (PLA) composite or a porous composite, and the composite is particularly useful as a scaffold for in situ pore formation. • [Previous techniques], fractures, hereditary malformations, bone defects in tumors and spinal surgery usually require implants. A typical absorbable tissue engineering scaffold should have sufficient porosity to allow osteocytes and blood vessels to ingrow. Important factors that determine the successful regeneration of tissues and organs include surface chemistry, porosity, pore microstructure and macrostructure, and stent shape. U.S. Publication No. 200300555 12 provides an injectable and moldable bone cement which comprises a biodegradable calcium-based compound comprising a sulfuric acid 4 bow, a base-filled limestone and a triterpenoid. However, this patent application does not provide a bioabsorbable stent. WO 2005/105170 relates to bone replacement compositions and methods of use. In a preferred embodiment, the composition comprises anhydrous sulfuric acid, barium sulfate dihydrate, and polyethylene glycol (PEG). CN 1724081 A provides a composite porous calcium sulphate scaffold having a polymer by polylactic acid or lactic acid/alkyd copolymer or polybasic acid or polycaprolactone or polybutyrate or polybutyric acid The ester copolymer or polyanhydride is dissolved in the gas, stirred, mixed with calcium sulfate in proportion, poured into a mold and dried to prepare the composite. US 2002018797 (A1) relates to a nano-calcium phosphate/collagen complex that mimics the composition and microstructure of the day 143659.doc 201221157, and from the complex with poly(lactic acid) (PLA) or poly ( Porous bone substitute and tissue engineering scaffold made of a complex of lactic acid co-glycolic acid xpLGA) US 200828143 1 provides a ceramic material capable of repairing a defect in a bone of a human or animal individual, comprising a porous body having a bioabsorbable coating Ceramic scaffolds and carriers comprising denatured demineralized bone. Such a ceramic may contain a material selected from the group consisting of hydroxyapatite, trisodium phosphate, _acid, carbonate, sulphate, and combinations thereof. However, the stent of the prior art described above does not provide sufficient compressive stress resistance. For optimal bone regenerative ability, it is best to use a porous scaffold with a two-dimensional (3-D) structure as a bone conduction matrix. Due to its spongy structure, the porous scaffold usually cannot withstand many physiological loads in the early stages of bone defect treatment. The porous stent tends to deform and lose its pore structure under load, and thus may be detrimental to certain clinical applications under pressure but still requiring space. For example, an 'interbody fusion cage, an artificial substitute used in a spinal fusion procedure, should have sufficient mechanical stability to support and transfer the load to maintain the intervertebral foramen height. Therefore, there is still a need to develop a bioabsorbable composite having appropriate mechanical properties at the beginning of transplantation. After the composite is embedded in the bone defect, the porous structure of the composite scaffold is formed in situ by in vivo degradation. SUMMARY OF THE INVENTION One object of the present invention is to provide a method for preparing a composite comprising calcium sulfate and polylactic acid, comprising the steps of: (a) being selected from calcium sulfate dihydrate, calcium sulfate alpha-hemihydrate or beta- Hemihydrate sulfuric acid 143659.doc 201221157 calcium or a mixture thereof is dehydrated to obtain anhydrous calcium sulfate; and (b) molten polylactic acid is melted at a high temperature, and molten polylactic acid is mixed with anhydrous calcium sulfate to form calcium sulfate-polylactic acid composite Wherein the ratio of polylactic acid to calcium sulfate is in the range of from about 8% to about 5% (w/w) to about 20% to about 50% (w/w). Another object of the present invention is to provide a composite prepared by the method of the present invention and also to provide a calcium sulfate comprising calcium sulphate dihydrate, calcium sulphate hemihydrate or calcium sulphate hemihydrate or a mixture thereof. a complex of polylactic acid, wherein the ratio of polylactic acid to calcium sulfate is in the range of about 80% to 50% (w/w) to about 2〇0/〇·50% (w/w). To provide a method of forming a porous scaffold in situ, which comprises embedding the complex of the present invention into a bone defect and degrading the complex in vivo to form a porous scaffold. Another object is to provide a method for preparing a porous composite comprising calcium sulfate and polylactic acid, comprising the steps of: Ο) selecting a calcium sulfate dihydrate, a calcium sulfate hemihydrate or calcium sulfate beta hemihydrate or Dehydrating calcium sulfate of the mixture to obtain anhydrous calcium sulfate; (b) melting the polylactic acid at a high temperature, and mixing the molten polylactic acid with anhydrous calcium sulfate to form a calcium-polylactic acid complex; and (e) the calcium-polylactic acid The composite is subjected to particle washing to form a porous composite having interconnected pores; wherein the ratio of polylactic acid to calcium sulfate is in the range of about 80% to 50% (w/w) to about 20% to 50% (w/w). The pore size of the interconnected pores is in the range of 1 〇〇 to 500 μηη. I43659.doc 201221157 A further object is to provide a porous composite prepared by the process of the invention. Also provided is a porous composite comprising sulfuric acid dance and polylactic acid selected from the group consisting of sulfuric acid dihydrate, sulfuric acid hemihydrate or β-hemihydrate sulfur, or a mixture thereof, wherein the ratio of polylactic acid to sulfuric acid is about 8 〇. %-5〇% is about 20〇/. Within the range of (w/w), and wherein the pores are interconnected and the pore size is in the range of 100 to 500 μπι. [Embodiment] The present invention provides a method of preparing a calcium sulfate-polylactic acid composite. Porous composites with more desirable mechanical properties prepared from calcium sulfate and polylactic acid in a specific ratio range. For example, it shows high surrender strength and Young's modulus. Due to its good mechanical properties, the composite can be used as an in situ perforated disc implant. As used herein, "macr〇p〇re" refers to a void formed by a polymer wall within a polymeric stent. Interconnecti〇n refers to a flow channel that connects macroscopic pores to each other. The interconnects comprise perforated interconnects (channels), microvia interconnects (channels), and nanopores of all of the materials defined above. The "yield strength" of a material is defined in engineering and materials science as the stress at which a material begins to plastically deform. The material is elastically deformed before the point of surrender and will return to its original state when the applied stress is removed. Once the surrender point is exceeded, some parts will be permanently and irreversibly deformed. "compressive strength" means the ability of a material to be axially orientated. "Young's modulus" (杨氏模数) means the material describing the hardness of a material. 143659.doc -6- 201221157 ^The raw material is therefore the most important in the design of the process - the number is also called the tensile modulus, and its A ^ Yang The hardness of the isotropic elastic material is defined as the ratio of the uniaxial stress and the uniaxial strain within the stress range controlled by Hooke's law::SLaW). This ratio can be determined experimentally from the slope of the stress-strain curve established during the tensile test of the material. Biodegradable" The action of a living being or self-acting. (biodegradable) means an implant that can be broken down into a product that is easily metabolized by hydrolysis of cells in vivo. (-ant) and the like to indicate the placement of foreign substances in medical treatment such as disease, injury or trauma. In the patient's body. The term "b〇ne defect" refers to any area of bone defect, such as voids, fissures, or other discontinuities in the bone. For example, a bone defect can be inherently caused by a disease or trauma such as a pathological, inflammatory or tumor disease. A method of preparing a composite comprising sulfated polylactic acid and a composite prepared therefrom, in a heart sample, the present invention provides a method of preparing a composite comprising calcium sulfate and polylactic acid, comprising the steps of: (a) selecting from Calcium sulfate dihydrate, α_calcium sulfate hemihydrate or calcium sulfate hemihydrate or a mixture thereof is dehydrated to obtain anhydrous calcium sulfate; and (b) molten polylactic acid is melted under a crucible/dish, and the polylactic acid is melted and anhydrous Calcium sulphate is mixed to form a calcium-polylactic acid complex; wherein the ratio of polylactic acid to calcium sulphate is in the range of about 8% to 5% (w/w) to about 143,659.doc 201221157 20% to 50% (w/w) Inside. In step (a) of the process of the invention, barium sulphate is dehydrated to obtain anhydrous bismuth sulphate. This dehydration step is used to reduce the adverse effects of water in the process of the invention. In the process of smelting polylactic acid, the presence of water will destroy the intermolecular vinegar bond and cause the cleavage of polylactic acid. Therefore, the high water content in the process will cause the degradation of polylactic acid and reduce the strength of the composite. Different forms of calcium sulphate can be used to control the crystal form and size of anhydrous calcium sulphate. According to the present invention, the sulfuric acid may be dihydrate sulfuric acid, alpha-hemihydrate sulfuric acid or beta-hemihydrate sulfuric acid or a mixture thereof. Barium sulfate is preferably a beta-hemihydrate sulfuric acid. In the step (b) of the present invention, the polylactic acid is melted at a high temperature and then mixed with anhydrous sulfuric acid to form a poly-lactic acid complex, wherein the ratio of the polylactic acid to the sulfuric acid is about 80% to 50%. (w/w) is in the range of about 20%-5 〇% (vv/w). The ratio of polylactic acid to calcium sulfate is preferably from about 75% to 50% (w/w to about 25% to 50% (w/w), about 75% to 55% (w/w) to about 25%. -40% (w/w), about 75%-60% (w/w) to about 25%-45./〇(w/w) or about 750/〇-65% (w/w) to about 25 In the range of %-35% (w/w), the ratio of polylactic acid to sulfuric acid is preferably 70% to 30% (w/w) » The temperature of molten polylactic acid is known in the art. Preferably, it is in the range of from about 120 ° C to about 300 ° C. The elevated temperature is preferably about 15 Torr. (: to about 300 t: from about 15 ° C to about 280 ° C, from about 150 ° C to about 250 ° C, in the range of from about 180 ° C to about 30 (TC, from about 180 ° C to about 280 ° C, from about 180 ° C to about 25 ° C or from about 200 ° C to about 250 ° C. The elevated temperature is better at about In another aspect, the present invention provides a complex for preparing 143659.doc 201221157 by the method of the present invention. The composite of the present invention comprises a salt selected from dihydrate sulfuric acid. Calcium sulfate and polylactic acid of α-hemihydrate calcium sulfate or β-hemihydrate sulfuric acid or a mixture thereof, wherein the ratio of polylactic acid to calcium sulfate is from about 80% to 50% (w/w) to about 20% to 50% Within the range of (w/w). The ratio of calcium acid is preferably about 75 〇 / 〇 _ 50% (w / w) to about 25% - 50% (w / w), about 75% - 55% (w / w) to about 25% -40 % (w/w), about 75%-60% (w/w) is about 25%-45% (w/w) or about 75%-65% (w/w) is about 25%-35. Within the range of 〇(w/w), the ratio of polylactic acid to calcium sulfate is more preferably 70% to 30% (w/w). According to the present invention, calcium sulfate is preferably β-calcium sulfate hemihydrate. The composite has initial mechanical properties sufficient to maintain stability of the bone defect region for a long period of time. The composite of the present invention is biodegradable and has high yield strength and Young's modulus. Therefore, the composite has suitable mechanical properties to allow formation. In addition, the complex has a higher degradation rate than polylactic acid and, therefore, provides more space for the growth of new bones to improve the stability of bone fusion. In a method of forming a porous stent in situ, The present invention also provides a method of forming a porous scaffold in situ comprising embedding a complex of the present invention into a bone defect and decomposing the complex in vivo to form a porous scaffold. In an embodiment, the porous scaffold is a vertebra Thin The graft of the present invention is a technique of bone arthroplasty using bone repair or replacement. The complex can be directly transplanted to the 4th position where bone growth is required. In the preferred embodiment, the complex is pre-bound to the desired The shape of the bone is lacking in the shape of t H. The initial & strength of the composite is sufficient to maintain the stress during the initial stages of migration. After a long time of transplantation, due to the different degradation rates of polylactic acid and sulfuric acid 143659.doc 201221157 calcium, the composite forms a porous configuration with a variety of pore sizes including macroscopic pores, microscopic pores and nanopores. The iso-pores are interconnected structures. Therefore, the purpose of the PLA/CS stent system for in situ pore formation is to provide mechanical stability during the early stages of healing. Thereafter, the calcium ions released from the dissolution of calcium sulfate and the resulting pore structure provide further favorable conditions for osteocytes and blood vessels to grow inward. Method for preparing a porous composite comprising sulfuric acid dance and polylactic acid and porous composite prepared therefrom In another aspect, the present invention provides a method for preparing a porous composite comprising sulfuric acid and polylactic acid, comprising the following steps : (a) dehydrating calcium sulfate selected from calcium sulfate dihydrate, calcium sulfate alpha-calcium sulfate or calcium sulfate beta-sulphate or a mixture thereof to obtain anhydrous barium sulfate; (b) melting polylactic acid at a high temperature, and The molten polylactic acid is mixed with anhydrous calcium sulfate to form a calcium-polylactic acid composite; and (c) the about-polylactic acid composite is subjected to particle washing to form a porous composite having interconnected pores; wherein the polylactic acid and the calcium sulfate The ratio is in the range of about 80%-50% (w/w) to about 20%-50% (w/w), and the pore size of the interconnected pores is in the range of 1 〇〇 to 500 μη. Step (a) and step (b) and the examples thereof are consistent with those mentioned in the method of preparing a composite comprising calcium sulfate and polylactic acid, wherein the ratio of polylactic acid to calcium sulfate is about 80% - 50 The 〇/〇 (w/w) ratio is in the range of about 20%-50% (w/w). The ratio of polylactic acid to calcium sulfate is preferably about 75%·5〇% (w/w) to about 25〇/〇-50% (w/w), and about 75%-550/〇 (w/w) ratio. About 25%-40% (w/w), 143659.doc •10- 201221157 ^75%-60〇/〇(w/w)tb ^250/0-450/0 (w/w), t^75 %-65% (w/w) is in the range of about 25%-35% (w/w)i. The ratio of polylactic acid to calcium sulfate is preferably 70% to 30% (w/w). Regarding the step (〇, the calcium-polylactic acid composite is subjected to particle washing to form a porous composite having interconnected pores. Particle washing technology has been widely used to manufacture 3D porous scaffolds for tissue engineering applications. Solubilization involves the production of a suspension of the polymeric composite in a solvent. The preferred solvent is water, preferably distilled deionized water, which does not/resolve the polymer or cause significant polymer hydrolysis during the time required for treatment. Grinding porogen particles (such as salt, gelatin or waxy hydrocarbon particles) and sieving into small particles, and transferring the particles of the desired size into the mold. The polymer suspension is then cast into the pores. The solvent is removed in the mold-filled mold by evaporation under large chaos and/or vacuum. After evaporation of the solvent, the porogen crystals are filtered by immersion in water to form a porous structure. According to the present invention, porous composite The pore size of the interconnected pores of the object is in the range of from 100 to 500 μm. The pore size is preferably in the range of from 15 Å to 45 Å μηη or from 2 Å to 400 μηη. In a preferred embodiment of the invention, the gas Sodium (NaCl) is used as the porogen and the concentration of NaCi remaining in the particle washing of step (c) is less than 10 ppm. In another aspect, the present invention provides a porous composite prepared by the method of the present invention. The porous composite of the present invention comprises calcium sulfate and polylactic acid selected from calcium sulfate dihydrate, calcium sulfate alpha-hemihydrate or calcium sulfate hemihydrate or a mixture thereof, wherein the ratio of polylactic acid to calcium sulfate is about 8〇. % 5〇% (w/w) is in the range of about 20%-50% (w/w), and the pores are interconnected and the pore size is in the range of 100 to 500 μη. The ratio of polylactic acid to calcium sulfate Compared with 143659.doc 201221157, about 75%-50% (w/w) is about 25°/〇-50% (w/w), about 75%-55% (w/w) is about 25°/〇. -40% (w/w), about 75%-60% (w/w) to about 25%-45% (w/w) or about 75%-65./〇(w/w) to about 25% In the range of -35% (w/w), the ratio of polylactic acid to calcium sulfate is preferably 70% to 30% (w/w). The pore size is preferably in the range of 150 to 45 0 μηη or 200 to 400 μηι. According to the present invention, the calcium sulfate is preferably calcium sulfate beta-hemihydrate. The composite may have a porous structure which reduces the initiality of the composite. Limiting the compressive stress and increasing the rate of degradation of the composite. Surprisingly, the porous composite of the present invention provides a higher rate of cell adhesion, and the cells cultured in the complex have higher alkaline phosphatase activity and higher. Osteopontin (ΟΡΝ) and bone sialoprotein (BSP) mRNA expression. EXAMPLES Example 1 The composite of the present invention was prepared by dehydrating polylactic acid and calcium sulfate beta-hemihydrate by drying. The polylactic acid was placed in an oven and dried at a temperature of about 50 ° C for 2 days. The β-hemihydrate calcium sulfate was dried at a temperature of about 50 (TC) for 1 hour, then moved to an oven and dried at 50 ° C for 2 days. The dried β-hemihydrate sulfuric acid was dried by heating the melt-dried polylactic acid. Calcium is added to the molten polylactic acid at a ratio of 20% to 80%, 30% to 70%, or 40% to 60°/, and mixed at a temperature of about 220 ° C to obtain a composite of the present invention. Example 2 Preparation of the Porous Composite of the Present Invention The porous composite of the present invention was prepared using a composite of polylactic acid and β-hemihydrate calcium sulfate having a ratio of about 70% to about 30% obtained in Example 1. 143659.doc 201221157 The composite of Example 1 was heated to about 220 ° C, and then NaC was added thereto. The obtained porous composite was filled into a circular mold, followed by cooling to room temperature. The porous composite was heated and cooled at ll ° ° C. The material was allowed to cool for 4 hours and then cooled to room temperature. The resulting porous composite was taken out from the mold and the surface of the composite was rubbed with sandpaper. Then 'the porous composite was immersed in distilled water to remove NaC. The resulting multi-tie composite was placed in an oven. Dry at a temperature of about 50 ° C for 1 day. Example 3 composite of the present invention The compressive strength test measures the compressive strength according to the compressive strength test standard ASTM D695 using a hydraulic material testing machine. The inclusion ratio prepared as mentioned in Example i is 20% to 80%, 30%. The compressive strength test is performed on a composite of poly-lactic acid of β-hemihydrate sulfuric acid at a ratio of 70°/. or 40% to 60%. The ratio of the inclusion ratio is 30°/〇 at 〇, 1 and 3 months. 70% of the composite of β-hemihydrate calcium sulfate and polylactic acid was further tested for compressive strength. Figure 1 (Α) and (Β) showed a ratio of 20 ° /. 80%, 30% to 70% or 40 °/. Compression stress (Α) and Young's modulus (Β) of a composite of 60% β-hemihydrate sulfuric acid and polylactic acid. The above composite exhibits favorable compressive stress. Figure 2 (Α) and show After one month, the compressive stress (Α) and Young's modulus (Β) did not change significantly, so the composite of the present invention can maintain stability for at least one month (ρ: polylactic acid complex; PC: the inclusion ratio of Example 1) 30% to 70% of the complex of β-hemihydrate calcium sulfate and polylactic acid. After 3 months, although the complex has been degraded, it remains acceptable. The compressive strength test was performed on the porous composite prepared in Example 2 during the period of 〇 to 3 months. Figure 3 (A) and (Β) show the compressive stress (Α) and Young's in the period of 〇 to 3 months. Modulus (Β) (ρΡ: porous polylactic acid; pPC: porous 143659.doc 13 201221157 composite of Example 2). After 1 month, the compressive stress and Young's modulus of the porous composite of Example 2 did not change significantly. Thus the porous composite of the present invention can remain stable for at least one month. After 3 months, the composite retains acceptable stress despite the degradation exhibited. Example 4 The information of ribonucleic acid (mRNA) of osteopontin (ΟΡΝ) and bone sialoprotein (BSP) in osteoblasts inoculated in the complex of the present invention and the porous composite will be expressed from 2 years old Schborg Osteoblasts obtained from the skull of the Sprague Da wley rat were inoculated and attached to the complex of Example 1 and the porous complex of Example 2. The cells were cultured for 3 weeks with α-ΜΕΜ containing 50 pg/ml of L-ascorbic acid 2-decanoate, 1 mM mM β-glycerophosphate, and 1% FBS. The QIAGEN RNeasy® Mini Kit (Cat. No. 74104; QIAGEN, CA, U.S.A.) was used to measure the amount of mRNA of the cells of the complex of Example 1 and the porous complex of Example 2 according to the manufacturer's instructions. 4 shows that the osteoblasts cultured in the composite of the present invention and the porous composite exhibit high expression levels of OPN mRNA and BSP mRNA (P: polylactic acid complex; pP: porous polylactic acid; PC: the inclusion ratio of Example 1 is 3〇0/〇 ratio 70% β-sodium hydrosulfate complex with polylactic acid; ppc: porous composite of Example 2; B: black; wi: week 1; W2: week 2; W3: 3 weeks). Example 5 Method for in situ formation of a porous scaffold A defect of 28 3 mm 2 was drilled in the mandible of a Lanyu pig. A scaffold of the polylactic acid complex scaffold and the scaffold of the β-hemihydrate calcium sulfate and polylactic acid of Example 1 were separately implanted into the defect. After 8 weeks, as seen by the results of x-ray photograph 143659.doc 201221157 (see Figure 5), the size of the defect implanted in the polylactic acid stent was reduced to 16.3 ± 2.0 mm2, and the defect of implanted polylactic acid and calcium sulfate stent was The size is reduced to 8.3 ± 0.9 mm2. It is apparent that the composite of Example 1 produced an unexpected effect relative to the polylactic acid stent. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 (A) and (B) show a composite of β-hemihydrate calcium sulfate and polylactic acid having a ratio of 20% to 80%, 30% to 70% or '40% to 60%. Compressive Stress - (Α) and Young's Modulus (B); Figure 2 (A) and (Β) show a ratio of 30% to 70% β-hemihydrate calcium sulfate and polylactic acid during 3 months Compressive stress (Α) and Young's modulus (B) of the composite; Figures 3(A) and (B) show compressive stress (A) and Young's modulus (B) during 0 to 3 months; Figure 4 shows that the complex of the present invention and the porous composite allows cultured osteoblasts to exhibit high expression levels of OPN mRNA and BSP mRNA; and Figure 5 shows the size of defects in the implanted polylactic acid and calcium sulfate scaffold minus 143659.doc • 15 ·