Phosphonium-containing diblock copolymers for enhanced colloidal stability and efficient nucleic acid delivery

Sean T. Hemp, Adam E. Smith, Joshua M. Bryson, Michael H. Allen, Timothy E. Long

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


RAFT polymerization successfully controlled the synthesis of phosphonium-based AB diblock copolymers for nonviral gene delivery. A stabilizing block of either oligo(ethylene glycol9) 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 (Mn = 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 2O, 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.

Original languageEnglish (US)
Pages (from-to)2439-2445
Number of pages7
Issue number8
StatePublished - Aug 13 2012
Externally publishedYes

ASJC Scopus subject areas

  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry


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