本研究利用具有酸鹼及溫度應答性的接枝共聚合高分子poly(acrylic acid-co-methacryloylethyl acrylate)-g-poly(N-isopropylacrylamide/ethylene glycol) (P(AAc-co-MEA)-g-PNIPAAm/PEG)與化療藥物doxorubicin (DOX)進行複合，經升溫及交聯等程序後，製備出載藥高分子奈米微胞，並評估其應用於癌症治療的可行性。其製備流程是，先將接枝共聚合高分子於pH 7.4的環境下與抗癌藥物DOX進行複合，接著升高溶液溫度至45 oC，使PNIPAAm產生的疏水性，並與AAc/DOX複合物一同構建複合奈米微胞的疏水核心。最後再加入起始劑(Ammonium peroxydisulfate, APS)，使高分子主鏈上MEA單元彼此聚合交聯複合奈米微胞。交聯後的複合奈米微胞粒徑約為53.3 ± 1.3 nm，並且具有良好的穩定性。其藥物的包覆效率及藥物裝載率分別可達80 wt%及奈米微胞總重的40 wt%。在體外模擬藥物釋放的測試中，載藥奈米微胞於藥物釋放上，展現出酸鹼應答的特性。其於72小時內的累積藥物釋放率， 於pH 7.4、6.0及4.7分別可達到17、32、50%。有趣的是，一但提升載藥奈米微胞所處環境溫度至45 oC，載藥奈米粒子的藥物釋放率即會顯著提升，於pH 4.7可達到68 %。此一特性，將有助於結合高能聚焦式超音波，對局部組織進行升溫，促進載藥奈米微胞進行藥物釋放。將載藥奈米微胞與癌細胞(HeLa cells)共同培養，並對此癌細胞進行細胞毒性分析。其結果顯示，複合奈米微胞載體本身並不具有明顯細胞毒性。然而，一但載藥奈米微胞被癌細胞吞噬而進入細胞內部，將能有效釋放其所載藥物，並且對癌細胞產生毒性。這證明了此交聯式複合奈米微胞於藥物傳遞系統中做為藥物載體的可行性。

In this study, the complex micelles were formed by electrostatic interaction between hydrophilic anticancer drug doxorubicin (DOX) and graft copolymers. The graft copolymers comprising acrylic acid and 2-methacryloylethyl acrylate (MEA) units as backbone and both poly(N-isopropylacrylamide) (PNIPAAm) and poly(ethylene glycol) (mPEG) as the grafts were synthesized. These micelles contain high stability by interchains cross-linking. After cross-linking, the particle size of polymeric complex micelles were ca. 53 nm and could be achieved high drug encapsulation efficiency (ca. 80 wt%) and loading content (ca. 40 wt%). In pH-triggered release, DOX were obviously released at pH 4.7 via the protonation of AAc residues on the copolymers, however, DOX would be contained in the micelles at pH 7.4. Besides, the released profile of these micelles was also thermal response. Because of the PNIPAAm on the copolymers, the released profile of micelles would be enhanced when the surrounding temperature was raised. In vitro cytotoxicity tests demonstrated the copolymers used in polymeric complex micelles were nontoxic while DOX-loaded polymeric complex micelles had well toxicity against Hela cells. Moreover, flow cytometry and confocal microscopy also showed the cellular uptake of polymeric complex micelles by Hela cells. These results indicate that these polymeric complex micelles could be provided with pH/thermo-triggered release profile and have highly potential in drug delivery system.

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