| Summary: | 碩士 === 國立臺灣大學 === 生物化學暨分子生物學研究所 === 90 === It is known that gene delivery using non-viral vectors such as liposomes is a pretty good method when compared with traditional viral infection. The advantages of liposomes being vectors for gene delivery are their non-toxic, convenient-preparing features. Nevertheless, the obstacles in gene delivery using liposomes are their low efficiency and specificity to particular cells. To promote the gene targeting to specific cells, some targeting ligands or antibodies are used to form immunoliposomes that can bind to target cells via ligand-receptor interaction. In this study, we developed a special gene delivery system which targeted to EGFR overexpressing tumor cell lines, A431 (Her1), SKBR-3 and SKOV-3 (Her2) via immunoliposomes composed of antibody-streptavidin (Ab-SA) conjugates and biotinylated cationic liposomes (BCLs). We used SPDP and SMCC as the chemical cross-linkers that conjugated streptavidin (SA) and the anti-Her2 antibody or monoclonal antibody 225 (mAb225) together. The BCLs were composed of DOTAP, cholesterol and biotin-DPOE in the molar ratio 11: 9: 0.055. It was because the high affinity between SA and biotin, the Ab-SA conjugates could strongly bind to BCLs and formed immunoliposomes as result. In the binding and endocytosis assay for A431 cells, we proved that these biotinylated liposomes could bind to and be internalized by target cells efficiently via mAb225-SA conjugates. In additional, we delivered the reporter genes pCMV-Luc or pCMV-EGFP, which formed complexes with the immunoliposomes developed above, to the target cells (A431, SKBR3 or SKOV3). The results showed that the immunolipoplexes really improved the gene targeting efficiency in contrast to the plain lipoplexes in vitro study, which referred that the Ab-SA-biotin-liposomes could be fine gene targeting vectors.
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