成功的基因治療都依賴傳遞載體系統，一個良好的基因載體有兩個最重要的條件：有效的轉染和低細胞毒性。本研究主要目的在發展新的質體DNA載體聚胺酯系統，並評估其生化性質。這些聚胺酯類顯示能有效縮合質體DNA，形成奈米大小並帶有正電荷的複合體。
首先我們合成了聚(酯-胺基甲酸酯) (PEU)，此共聚合物含有胺基甲酸酯及酯的官能基於主鏈而側鏈則帶有胺基。由動力光學散射儀測定，發現此種陽離子型高分子PEU可與DNA形成奈米級的複合體，粒徑大小為120-195 nm且帶正電。水解實驗中可得到PEU水解半生期為35小時，從緩衝實驗可得知此高分子具有不錯的緩衝效率。最後利用COS-7細胞株與HELA細胞株做毒性測試並與PEI做比較，得到具低毒性的結果。接著我們藉由合成出在高分子的主鏈及側鏈皆帶有胺基的新陽離子型聚酯高分子poly(ester-g-ethylenimine) PEU-g-PEI800，實驗結果發現，此種陽離子型高分子可與DNA形成奈米級的複合體，粒徑大小為80-196 nm且帶正電。水解實驗中可得到PEU-g-PEI800水解半生期為10小時，從緩衝實驗可得知此高分子具有不錯的緩衝效率，此新型的聚酯亦具有極低的細胞毒性。
二種聚酯都能與DNA自組裝成奈米大小複合體，聚合物/DNA複合體直徑皆小於200 nm以下，並比一般使用於DNA高分子載體PEI，具有更低的細胞毒性。 The success of gene therapy is largely dependent on the delivery vector system. Efficient transfection and nontoxicity are two of the most important requirements of an ideal gene delivery vector. The main objective of the present work was the development of new carrier systems for the delivery of plasmid DNA. Novel degradable poly(ester amine)s were evaluated as variety properties. poly(ester amine)s were shown to effectively condense plasmid DNA into nano-sizedand positively charged complexes. poly(ester amine)s were able to combine with DNA and yield complexes with positive charge .
We synthesized Poly(ester urethane)s (PEU) bearing urethane and amines in the side chain. Poly(ester urethane)s (PEU) , readily self-assembled with the plasmid DNA (ρCMV-βgal) in HEPES buffer, were characterized by dynamic light scattering, zeta-potential. The results revealed that PEU was able to combine with DNA and yield complexes with positive charge of size around 120-195 nm . The degradation studies indicated that the half-life of PEU in HEPES buffer is 24 hours. Titration studies were performed to determine the buffering capacities of the polymers. In addition, the COS-7 cell and HELA cell viabilities in the presences of PEU and PEI were studies.
.We synthesized Poly(ester-g-ethylenimine) (PEU-g-PEI800) bearing urethane and ester linkages in the backbone and amines in the side chain. Poly(ester-g-ethylenimine) (PEU-g-PEI800), readily self-assembled with the plasmid DNA (ρCMV-βgal) in HEPES buffer, were characterized by dynamic light scattering, zeta-potential. The results revealed that PEU-g-PEI800 was able to combine with DNA and yield complexes with positive charge of size around 80-196 nm . The degradation studies indicated that the half-life of PEU-g-PEI800 in HEPES buffer is 12 hours. Titration studies were performed to determine the buffering capacities of the polymers. In addition, the COS-7 cell and HELA cell viabilities in the presences of PEU-g-PEI800 and PEI were studies.
Two kind of polyesters readily self-assembled with plasmid DNA into nano-sized polymer/DNA complexes less than 200 nm diameter and significantly less cytotoxicity than commonly used DNA delivery polymer, poly(ethylene imine)(PEI) in vitro.
