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, photoiniferter 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
2-fold 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.