Copolymers of NVAm and NVP for efficient gene delivery

Gene delivery lies at the heart of many approaches for treating a host of different diseases. Promising candidates for the delivery of genetic material are polycationic vectors; however, managing toxicity arising from adverse interactions with the lipid bilayer remains a challenge. In this work, photo-iniferter reversible addition-fragmentation chain-transfer PI-RAFT polymerization was used to synthesize statistical copolymers of N-vinyl formamide (NVF) and N-vinyl pyrrolidone (NVP). Subsequent selective hydrolysis of NVF was used to introduce polyvinyl amine (PVAm) repeats. The resulting library of polymers with varying charge densities and molar masses was probed for biocompatibility with erythrocytes and MDA-MB-468 cells, revealing substantially reduced cytotoxicity compared with linear polyethylene imine (lPEI) and Lipofectamine 2000. Using an ethidium bromide (EtBr) replacement assay PVAm copolymers were shown to replace EtBr at low N/P-ratios. The transfection conditions were optimized in terms of the N/P-ratio and polyplex concentration by a Renilla luciferase reporter assay. This revealed 30-fold less cytotoxicity, a much wider viable concentration range, and a twofold greater transfection efficiency for the PVAm copolymer compared to lPEI. This study provides insights into the PI-RAFT copolymerization of the less activated monomers NVF and NVP and highlights the potential of polyvinyl amine copolymers resulting from selective hydrolysis for the transfection of genetic material compared with lPEI.