利用聚乙二醇-芳香族聚酸酐奈米微胞包覆疏水性抗癌藥物於藥物輸送系統之研究

Encapsulation of hydrophobic anti-cancer drug by nano-micelles of methoxy poly(ethylene glycol-b-aromatic anhydride) in drug delivery system

洪鼎惟(Ding-Wei Hong)

指導教授 ： 朱一民

國立清華大學/工學院/奈米工程與微系統研究所/碩士(2010年)

摘要

兩性團聯共聚物因為疏水作用力能在水中自組裝形成微胞，因此可以包覆疏水性藥物，所以高分子微胞作為藥物載體在近年來受到很多研究者的重視和研究。
本研究利用親水性高的mPEG和疏水性的芳香族聚酸酐，經熔融縮合得到四種不同的兩性高分子(mPEG5000CPP、mPEG5000CPH、mPEG2000CPP、mPEG2000CPH)。1H-NMR、FT-IR及GPC確立高分子的結構，由臨界微胞濃度(CMC)和表面化學結構鑑定，確定聚乙二醇-芳香族聚酸酐能夠在極低的濃度下形成微胞，並且形成穩定的疏水核心。在粒徑方面，皆能形成粒徑小於200 nm的微胞，並在30天內有良好的粒徑穩定度。降解後，也不會造成嚴重的pH值下降，並以MTT測試，可以發現無論何種材料及濃度皆對於正常的人類纖維母細胞沒有毒殺性，存活率皆高達90%以上。
紫杉醇、薑黃素皆是對於癌症具有療效的疏水性藥物，水溶解度很低（分別為1.17×10-6mole/L、2.99×10-8 mole/L），藉由本研究之奈米微胞包覆，可提高溶解度至少25及4.88×103倍以上。包覆藥物後的粒徑仍能維持在200 nm以下，包覆率方面，最高皆可達70% 以上，在藥物含量方面也可達3.00 %、6.75%。經由藥物釋放曲線可以發現包覆紫杉醇的釋放速率較慢於薑黃素，但兩者皆產生較低的突釋（initial burst）現象，且可以在15天內穩定的釋放。考量微胞粒徑、穩定度、藥物包覆率及藥物釋放，以mPEG5000CPP包覆紫杉醇（藥物與高分子重量比，D/P＝0.050）、mPEG5000CPP包覆薑黃素（D/P＝0.075）為最佳化條件。
將包覆疏水性抗癌藥物的微胞對子宮頸癌細胞HeLa進行細胞毒殺性試驗，發現當紫杉醇濃度6.27 ppm以高分子微胞包覆，即可殺死50%以上的細胞，證明藥物對於癌細胞仍具有毒性，且能在極低的濃度下殺死癌細胞；就薑黃素而言，僅需要4.66 ppm即可殺死50%以上的細胞。
由高分子微胞的基本性質、藥物釋放及細胞實驗可以知道聚乙二醇-芳香族聚酸酐所形成的奈米微胞為很好的疏水性藥物載體，對於癌症的藥物治療的應用上有相當的潛力。

關鍵字

芳香族聚酸酐 ； 兩性團聯高分子 ； 高分子微胞 ； 藥物釋放 ； 疏水性抗癌藥物

並列摘要

Polymeric micelles as drug carriers have drawn much attention in recent decades, because amphiphilic copolymers can self-assemble to form micelles in water due to hydrophilic and hydrophobic interactions.
In this study, poly(ethylene glycol) methyl ether and poly aromatic anhydride were used to act as hydrophilic and hydrophobic group, respectively. Four different polymers (mPEG5000CPP、mPEG5000CPH、mPEG2000CPP、mPEG2000CPH) were synthesized using melt condensation approach. The physical and chemical properties of polymer were evaluated by 1H-NMR、FT-IR and GPC. Through critical micelle concentration (CMC) and surface chemical structure analysis, we confirmed that micelles can be formed in very low concentration and had a stable hydrophobic core. The micelles sizes were measured smaller than 200 nm and had good stability during 30 days degradation test. The four different polymeric micelles showed low cytotoxicity toward human fibroblast cells by MTT assay.
With curative effect in cancer, hydrophobic drugs, paclitaxel and curcumin, which are difficult to dissolve in PBS (with solubility of 1.17×10-6 and 2.99×10-8 mole/L, respectively) are of interests. We can improve the solubility of paclitaxel fourty-fold and curcumin five thousand-fold by micelles encapsulation. Paclitaxel were incorporated into these micelles with encapsulation efficiency around 55% to 75%, depending on the different loading ratio and with drug content around 3.56%. High loading efficiency around 75% as well as drug content around 6.83% were observed in curcumin-loaded micelles. In both paclitaxel and curcumin micielles there were no initial burst phenomenon observed. Both micelles showed sustained release for about 18 days, with curcumin released faster than paclitaxel. According to the size of drug-loaded micelles，the stability of drug-loaded micelles，encapsulation efficiency and drug release curve, paclitaxel-loaded in mPEG5000CPP（D/P＝0.050）and curcumin-loaded in mPEG5000CPP（D/P＝0.075）are shown to be the best formulation for each drug we tested. Paclitaxel- and curcumin-loaded micelles showed IC50 values of about 6.27 and 4.66 ppm of the drugs, respectively, toward HeLa cell. This means that drugs are effective toward cancer cells and can kill cancer cells in very low concentrations.
As a result, we conclude that nano-micelles of methoxy poly(ethylene glycol-b-aromatic anhydride) may be suitable for encapsulating those hydrophobic anti-cancer drugs.

並列關鍵字

aromatic anhydride ； amphiphilic copolymer ； polymeric micelles ； drug release ； anti-cancer hydrophobic drug

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