交聯奈米微胞應用於藥物載體之特性研究及其光動力效果的評估

Abstract

近幾年來，奈米微胞的應用受到廣泛的討論，特別是在藥物傳遞系統上，因為內環疏水，外環親水的特性，可以在內環包覆入疏水藥物，而增加其在水溶液中的溶解度，本研究中將奈米微胞的外圍進一步的做交聯，使奈米微胞即使受到大量稀釋，也不容易瓦解，以提高奈米微胞作為藥物載體的穩定性。

光動力療法是結合了光感物質以及特定波長的光，應用於癌症的一種新療法。但許多使用於光動力療法上的光感藥物為疏水性，因此很難以靜脈注射的方式來給藥，為了增加這些疏水性光感藥物的生體可用率，因此本研究利用交聯奈米微胞來包覆光感藥物Protoporphyrin IX(PpIX)，並測定其粒徑及包覆入的藥物濃度。奈米微胞的生體可溶性是以細胞毒性試驗來評估，並利用螢光顯微鏡以及流式細胞儀來探討細胞攝入交聯奈米微胞的情形。交聯奈米微胞包覆PpIX的光動力效果，則是以發光二極體(LED)引發光動力效果後，探討其細胞毒性。

由實驗結果得知，所製備的交聯奈米微胞平均粒徑約為140 nm，而包覆PpIX後平均粒徑約為240 nm。細胞毒性試驗的結果顯示包覆PpIX的交聯奈米微胞對正常細胞可能有些微毒性。細胞攝入包覆PpIX之交聯奈米微胞的累積量隨著時間增加，於十二小時至二十四小時之間達到高峰。而光動力效果相較於同樣濃度未包覆的PpIX而言，所差無幾，照光時間五十秒即可殺死一半以上細胞。

綜上所述，本實驗針對交聯奈米微胞包覆藥物於體外的特性進行探討，這些結果將有助於瞭解交聯奈米微胞於光動力療法上之應用。

Polymeric micelles as drug carriers attract highly concern in recent years for their ability to incorporate hydrophobic drugs. In this study，we prepared the micelles from amphiphilic core-shell structure followed by intramicellare crosslinking between the polymeric chains, which were called as shell crosslinked nanoparticles(SCKs). SCKs increase the stability when encountering variable environments and expand their uses as drug carriers.

Photodynamic therapy (PDT) includes photosensitizers and specific light irradiation. Since many photosensitizers are hydrophobic, we incorporated protoporphyrin IX (PpIX) into SCKs to investigate the PDT effect in vitro. In this study, the size distribution and the drug amount incorporated into SCKs were determined. The cytotoxicity tests were designed to evaluate the biocompatibility of the SCKs. Moreover, we analyzed and quantified the uptake of SCKs encapsulated with PpIX in cells, and compared the PDT effect with free PpIX. The particle size of the SCKs without drug were about 140 nm，and the size of the SCKs with PpIX were about 240 nm. Cytotoxicity assay revealed that PpIX incorporated SCKs have some toxicity to normal cells. As shown in the results of fluorescence microscopy and flow cytometry, the uptake of SCKs with PpIX reach the maximum at the incubation time of 12-24 hours. The PDT effects of SCKs-PpIX show no significant differences with free PpIX. In summary, in vitro characterization and in vitro PDT effect of SCKs encapsulated with PpIX were studied. These results may lead to more successful development on the application of SCKs for photodynamic therapy.