As mutation and dysfunction of p53 gene could induce most of human cancers, the p53 tumor suppressor gene was used to replace them and recover their normal functions in cancer cells. In this paper, biotinylated transferrin/avidin/biotinylated disulfide containing PEI bioconjugates (TABP-SS) mediated p53 gene delivery system was formed attributed to the 'avidin-biotin bridge'. Characteristics of the obtained TABP-SS and its p53 complexes were evaluated in terms of acid-base titration, agarose gel electrophoresis, SEM, particle size and zeta-potential measurements. The acid-base titration results showed that TABP-SS had good buffer capability. The results of gel electrophoresis indicated that TABP-SS could fully condensed DNA and would be degraded by reducing agent inside cells. In vitro cell viability and transfection of TABP-SS were investigated in COS7, HepG2, and HeLa cells. Among the three different cell lines, TABP-SS exhibited much lower cytotoxicity and higher transfection efficacy in HepG2 and HeLa cells due to the specific interactions between transferrin ligands and their receptors on tumor cells. Apoptotic morphology was observed using confocal microscopy, and the expression of p53 protein in transfected cells was evaluated by western blotting. All the results indicated that TABP-SS/p53 complex could be considered as a low toxic and high efficient tumor targeted gene delivery system, which has great potential for further clinical application.
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