Abstract:

Cationic polyethylenimine (PEI) with dextran fluorescein anionic (DFA) or oligodeoxynucleotide (ODN) could form polyelectrolyte complex by self-assembly as a gene delivery vector. This study was designed to investigate the effects on pharmaceutical characteristics and cell uptake PEI after a long-circulation modification with poly(ethylene glycol) (PEG). DFA or ODN reacted with PEI or PEI-PEG to form polyelectrolyte complexes. Surface characters of these complexes and the retardation of ODN by PEI and PEI-PEG were evaluated. The uptake rates of DFA/PEI and DFA/PEI-PEG complexes by MCF-7 cells were evaluated by flow cytometry. Confocal laser scanning microscopy was utilized to visualize the internalization of these complexes. ODN/PEI complex showed the dependence of their size and ξ potential on the N/P ratio. ODN/PEI-PEG complex were much less affected by N/P ratio and their size was around 30 - 100 nm. PEI and PEI-PEG retarded ODN even at N/P ratio as low as 4, and complete retardation was found at N/P ratio of 8. The uptake rate by MCF-7 cells was direct correlated to the DFA concentration and incubation time, and the uptake rate could exceed 99% under the selected condition. The results in this study showed that PEI self-assembly polyelectrolyte complex after stealth or long circulation modification may increase the ability as a gene vector to delivery genes into cells.

Key words: Polyelectrolyte complex, Polyelectrolyte complex, Polyethylenimine, Polyethylenimine, Uptake rate, Uptake rate, Self-assembly, Self-assembly, Breast cancer cell, Breast cancer cell