Altering Amine Basicities in Biodegradable Branched Polycationic Polymers for Non-Viral Gene Delivery

摘要

In this work, biodegradable branched polycationic polymers were synthesized by Michael addition polymerization from different amine monomers and the triacrylate monomer trimethylolpropane triacrylate. The polymers varied in the amount of amines that dissociate in different pH ranges, which are considered to be beneficial to different parts of the gene delivery process. P-DED, a polymer synthesized from trimethylolpropane triacrylate and dimethylethylenediamine, had the highest number of protonated amines that are available for pDNA complexation at pH 7.4 of all polymers synthesized. P-DED formed a positive polyplex (13.9 ± 0.5 mV) at a polymer/plasmid DNA (pDNA) weight ratio of 10:1 in contrast to the other polymers synthesized, which formed positive polyplexes only at higher weight ratios. Polyplexes formed with the synthesized polymers at the highest polymer/pDNA weight ratio tested (300:1) resulted in higher transfection with enhanced green fluorescent protein reporter gene (5.3 ± 1.0% to 30.6 ± 6.6%) compared to naked pDNA (0.8 ± 0.4%), as quantified by flow cytometry. Polyplexes formed with P-DED (weight ratio of 300:1) also showed higher transfection (30.6 ± 6.6%) as compared to polyplexes formed with branched polyethylenimine (weight ratio of 2:1, 25.5 ± 2.7%). The results from this study demonstrated that polymers with amines that dissociate above pH 7.4, which are available as positively charged groups for pDNA complexation at pH 7.4, can be synthesized to produce stable polyplexes with increased zeta potential and decreased hydrodynamic size that efficiently transfect cells. This work indicated that polymers containing varying amine functionalities with different buffering capabilities can be synthesized by using different amine monomers and used as effective gene delivery vectors.