Phosphonium-containing diblock copolymers for enhanced colloidal stability and efficient nucleic acid delivery.
RAFT polymerization successfully controlled the synthesis of phosphonium-based AB diblock copolymers for nonviral gene delivery. A stabilizing block of either oligo(ethylene glycol(9)) methyl ether methacrylate or 2-(methacryloxy)ethyl phosphorylcholine provided colloidal stability, and the phosphonium-containing cationic block of 4-vinylbenzyltributylphosphonium chloride induced electrostatic nucleic acid complexation. RAFT polymerization generated well-defined stabilizing blocks (M(n) = 25000 g/mol) and subsequent chain extension synthesized diblock copolymers with DPs of 25, 50, and 75 for the phosphonium-containing block. All diblock copolymers bound DNA efficiently at ± ratios of 1.0 in H(2)O, and polyplexes generated at ± ratios of 2.0 displayed hydrodynamic diameters between 100 and 200 nm. The resulting polyplexes exhibited excellent colloidal stability under physiological salt or serum conditions, and they maintained constant hydrodynamic diameters over 24 h. Cellular uptake studies using Cy5-labeled DNA confirmed reduced cellular uptake in COS-7 and HeLa cells and, consequently, resulted in low transfection in these cell lines. Serum transfection in HepaRG cells, which are a predictive cell line for in vivo transfection studies, showed successful transfection using all diblock copolymers with luciferase expression on the same order of magnitude as Jet-PEI. All diblock copolymers exhibited low cytotoxicity (>80% cell viability). Promising in vitro transfection and cytotoxicity results suggest future studies involving the in vivo applicability of these phosphonium-based diblock copolymer delivery vehicles.
Department of Chemistry and Macromolecules and Interfaces Institute, Virginia Tech, Blacksburg, Virginia 24061, United States.
Sean T
ST
Hemp
Adam E
AE
Smith
Joshua M
JM
Bryson
Michael H
MH
Allen
Timothy E
TE
Long
D000818:Animals; D019556:COS Cells; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D003102:Colloids; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008689:Methacrylates / Q000737:chemistry* / Q000633:toxicity; D008970:Molecular Weight; D009943:Organophosphorus Compounds / Q000737:chemistry* / Q000633:toxicity; D010316:Particle Size; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000633:toxicity; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000633:toxicity; D058105:Polymerization; D014162:Transfection; D019076:Transgenes
D003102:Colloids; D008689:Methacrylates; D009943:Organophosphorus Compounds; C524499:polyethylene glycol methacrylate; D010767:Phosphorylcholine; D049452:Green Fluorescent Proteins; D011092:Polyethylene Glycols; C070638:2-methacryloyloxyethyl phosphorylcholine; D008156:Luciferases