Poly-L-Lysine-Poly[HPMA] Block Copolymers Obtained by RAFT Polymerization as Polyplex-Transfection Reagents with Minimal Toxicity.

Herein we describe the synthesis of poly-L-lysine-b-poly[N-(2-hydroxypropyl)-metha-crylamide)] (poly[HPMA]) block copolymers by combination of solid phase peptide synthesis or polymerization of α-amino acid-N-carboxy-anhydrides (NCA-polymerization) with the reversible addition-fragmentation chain transfer polymerization (RAFT). In the presence of p-DNA, these polymers form polyplex micelles with a size of 100-200 nm in diameter (monitored by SDS-PAGE and FCS). Primary in vitro studies with HEK-293T cells reveal their cellular uptake (FACS studies and CLSM) and proof successful transfection with efficiencies depending on the length of polylysine. Moreover, these polyplexes display minimal toxicity (MTT-assay and FACS-measurements) featuring a p[HPMA] corona for efficient extracellular shielding and the potential ligation with antibodies.