| Summary: | 碩士 === 國立中興大學 === 化學工程學系所 === 100 === 英文摘要
In this research, the block copolymer cholerterol-p(HEMA-co-lysine) and phospholipid (DPPC) were synthesized and self-assembled into the liposome-like structure , and formed the SPLexes ( Small Particular Lipoplexs ). The block copolymer , foliate-PEG-P(HEMA-co-histidine
-MMAc) , crosslink to the surface of the lipoplex by electric interaction. The PEG segments exist in the outer shell of lipoplex and provide the characterstic that could be stable in blood stream . MAAc and hisdidine moiety are responded and protonated by acidified environment and trigger the siRNA release.
The particle sizes and polydispersity were discussed to evaluate the affection of the weight ratio of block copolymers PI, PII and DPPC. From the result , the uniform and optimal particle size of lipoplex was around 70~80 nm . Based the optimal conditions , siRNA-VEGF was encapsulated with SPLexes efficiently and could be the potential candidate for siRNA delivery. For the result of MTS analysis , SPLexes showed a low cytotoxicity. For siRNA release, siRNA/SPLexes was stabilized at pH=7.4 and siRNA released under acidic condition . Due to MMAc molecules of PII protonated to become neutral , they caused the PII disassociated from the SPLexes surface. For anticancer activity , siRNA/SPLexes inhibited the VEGF protein expression to 74.5 ± 4.5 % and induced the apoptosis efficiently.
Photochemical internalization ( PCI ) is a technology based on photochemical reactions inducing rupture of endocytic vesicles and releasing siRNA into the cytoplasm.The main point of this research is contributed to the effort to develop lipoplexes based siRNA delivery systems via photochemical reactions . The results show that the 20FTPP-micelles bear were low photocytotoxicity . The observation indicates the production of reactive oxygen species in cytoplasm. The results of CLSM images show that endocytic vesicles ( containing 20FTPP
-micelles and siRNA/SPLexes respectively) are fused, and siRNA are released from endo/lysosome. Finally , through the mechanism , the siRNA/SPLexes inhibited the VEGF protein expression to 90%.
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