Photo-responsive degradable poly (beta-amino ester) toward non-viral gene delivery
Among synthetic cationic polymers, poly(beta-amino ester) (PBAE) is one of ideal candidates for non-viral gene therapy due to its desired gene delivery efficiency, biocompatibility, and biodegradability. In order to further improve the gene delivery efficiency of PBAE by facilitating the intracellular DNA dissociation, we herein report the design and development of a photo-responsive PBAE as a novel gene delivery vector which undergoes polymer degradation and promoted DNA release in response to external UV irradiation. Photo-responsive PBAE was synthesized by Michael addition of amines to (2-nitro-1,3-phenylene)bis(methylene) diacrylate (NPBMD) as a UV-responsive segment. Non-responsive PBAE (control polymer) was also synthesized when a UV-nonresponsive monomer 1,3-phenylenebis(methylene) diacrylate (PBMD) was used. By changing the monomer type and diacrylate/amine ratio, a library of UV-responsive PBAEs were obtained. Upon a screening process on the transfection efficiencies, A1-13700 was identified to be the top-performing candidate and thereafter subjected to the assessment of UV-responsive gene delivery properties. Gel permeation chromatography (GPC) and UV-vis analyses confirmed that UV irradiation triggered degradation of the responsive polymer but not the control polymer. The cationic PBAE condenses DNA into 100-nm complexes due to electrostatic interactions, and thus facilitated the cellular internalization via caveolae-mediated endocytosis. Upon UV-irradiation, particle size of the polymer/DNA complexes was augmented and DNA release was promoted as evidenced by an ethidium bromide exclusion assay and a gel retardation assay. As a result of the facilitated intracellular DNA release, UV irradiation post-transfection led to an up-to-2-fold improvement in terms of gene transfection efficiency in HeLa, COS-7, 3T3-L1 cells. Control polymers exhibited unappreciable alteration in the above assessments, further substantiating the trigger-responsive performance of PBAE towards UV light. The cytotoxicity of the polymer was slightly reduced upon UV irradiation, which suggested the degradation of cationic polymer induced cytotoxicity upon polymer degradation. This study thus provides an effective modulation over the gene transfection process using external stimuli, and helps overcome the intracellular barriers against non-viral vector mediated gene transfer.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign