科研之友
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摘要
Cationic polymers have been widely explored as non-viral gene delivery vectors. The high density of cationic charges and high molecular weight of cationic polymers enable them efficiently condense DNA into nanosized polyplexes, which protect DNA from degradation and facilitate DNA cellular internalization. However, these characters also make the polyplexes hardly dissociate to release DNA, hindering its access to the DNA transcription process for gene expression. In this study, we synthesized two kinds of linear quaternized ammonium-based cationic polymers from 2,6-dibromomethylphenolic esters using Menschutkin Reaction. The esterases in cytosol could hydrolyze the phenolic ester and trigger a self-immolative chain fragmentation, leading to the quick release of the packed DNA for efficient transcription. The DLS measurements of the size and zeta potential of the resulting polyplexes showed that these cationic polymers could pack DNA molecules efficiently into positively-charged nanoparticles. Agarose-gel electrophoresis experiment revealed that anionic DNA molecules were condensed stably and compactly with cationic polymers. Furthermore, self-immolative elimination was successfully monitored by high performance liquid chromatography (HPLC), which confirmed the esterase-responsiveness and compatibility of this well-designed cationic polymers. Gel retardation assay showed that the packed DNA could be quickly released after incubation with esterase solution, indicating that the polyplexes would become incompact and disassemble once in the cytosol. Meanwhile, compared with commercially available PEI, the polycation had a lower cytotoxicity in cancer cells, which might contribute to the fragmentation and the removal of the quaternary amine cationic charges. In A549 and Hela cancer cells, these two kinds of polyplexes achieved excellent gene transfection efficiency. But complex 1 was better than complex 2 at high N/P ratios, thanks to the activation of self-immolative elimination by intracellular esterases.
- 出版日期2017-6-20
- 单位浙江大学
