Low polydispersity (N-ethyl pyrrolidine methacrylamide-co-1-vinylimidazole) linear oligomers for gene therapy applications

Nonviral methods for gene delivery are becoming ever more prevalent along with the need to design new vectors that are highly effective, stable in biological fluids, inexpensive, and facile to produce. Here, we synthesize our previously reported monomer N-ethyl pyrrolidine methacrylamide (EPA) and evaluate its effectiveness in gene vector applications when copolymerized with 1-vinylimidazole (VI). A range of these novel linear cationic copolymers were synthesized via free radical polymerization with low molecular weights (oligomers) and low polydispersities showing two pK_a values as the two co-monomers are cationic. DNA-polymer polyplexes had average sizes between 100 and 250 nm and zeta-potentials between 10 and 25 mV, and a strong dependence of composition on the size on the zeta-potential was observed. The cytotoxicity of the homopolymers, oligomers, and polyplexes toward human fibroblasts and 3T3 mouse fibroblasts was evaluated using the MTT and AlamarBlue™ assays, proving that formulations could be made with toxicity as low as low molecular weight linear poly (dimethylaminoethyl methacrylate) (PDMAEMA). The transfection capability of the polyplexes measured using the G-luciferase marker gene far superseded PDMAEMA when evaluated in biological conditions. Furthermore, blood compatibility studies showed that these new oligomers exhibit no significant hemolysis or platelet activation above PBS controls. These new EPA based oligomers with low toxicity and ease of scalability show high transfection abilities in serum conditions, and blood compatibility showing its potential for systemic gene delivery applications.