Copolymers of 2-(dimethylamino)ethyl methacrylate with ethoxytriethylene glycol methacrylate or N-vinyl-pyrrolidone as gene transfer agents

Random copolymers of 2-(dimethylamino)ethyl methacrylate (DMAEMA) with etho xytriethylene glycol methacrylate (triEGMA) or N-vinylpyrrolidone (NVP) of different molecular weights and compositions were synthesized, characterize d and evaluated as polymeric transfectants in vitro. All synthesized copoly mers (comonomer fraction lip to 66 mol%) were able to bind to DNA, yielding polymer-plasmid complexes (polyplexes). However, the polymer-plasmid ratio at which small complexes (size 0.2-0.3 mu m) were formed, increased with i ncreasing mole fraction of the comonomer. zeta-Potential measurements revea led that the polymer-plasmid ratio where charge neutralization of DNA occur red, increased with increasing mole fraction of triEGMA. The cytotoxicity o f the copolymers, either complexed with DNA or in the free form, decreased with increasing mole fraction of both comonomers (triEGMA and NVP). This re duction was even more than what could be expected based on the DMAEMA mole fraction in the copolymer. The copolymers with a molecular weight up to 170 000 had the same transfection capability as a homopolymer of comparable mo lecular weight. However, higher molecular weight copolymers showed a reduce d transfection capability compared to the homopolymer, which was ascribed t o the reduced capability to condense the size of plasmid. Transfection effi ciency of polyplexes composed of copolymers with a low triEGMA content incr eased with increasing molecular weight. Although the copolymers with 50 mol % triEGMA were also better transfectants than the homopolymer, the transfec tion efficiency did not increase further with increasing molecular weight. Interestingly, NVP-DMAEMA copolymers synthesized by polymerization to high conversion showed both excellent DNA binding and condensing characteristics (polyplex size <0.3 mu m) and transfection capabilities. This is ascribed to a synergistic effect of DMAEMA-rich copolymers and NVP-rich copolymers p resent in this system on the complex formation with plasmid DNA. (C) 2000 E lsevier Science B.V. All rights reserved.