Influence of polycation molecular weight on poly(2-dimethylaminoethyl methacrylate)-mediated DNA delivery in vitro

John M. Layman, Sean M. Ramirez, Matthew D. Green, Timothy Edward Long

Research output: Contribution to journalArticlepeer-review

120 Citations (Scopus)


Establishing clear structure-property-transfection relationships is a critical step in the development of clinically relevant polymers for nonviral gene therapy. In this study, we determined the influence of poly(2- dimethylaminoethyl methacrylate) (PDMAEMA) molecular weight on cytotoxicity, DNA binding, and in vitro plasmid DNA delivery efficiency in human brain microvascular endothelial cells (HBMEC). Conventional free radical polymerization was used to synthesize PDMAEMA with weight-average molecular weights ranging from 43 000 to 915 000 g/mol. MTT and LDH assays revealed that lower molecular weight PDMAEMA (Mw = 43 000 g/mol) was slightly less toxic than higher molecular weights (Mw > 112 000 g/mol) and that the primary mode of toxicity was cellular membrane destabilization. An electrophoretic gel shift assay revealed that all PDMAEMA molecular weights completely bound with plasmid DNA. However, heparin competitive binding experiments revealed that higher molecular weight PDMAEMA (Mw = 915 000 g/mol) had a greater binding affinity toward plasmid DNA than lower molecular weight PDMAEMA (Mw = 43 000 g/mol). The molecular weight of PDMAEMA was found to have a dramatic influence on transfection efficiency, and luciferase reporter gene expression increased as a function of increasing molecular weight. However, cellular uptake of polyplexes was determined to be insensitive to PDMAEMA molecular weight. In addition, our data did not correlate polyplex size with transfection efficiency. Collectively, our data suggested that the intracellular fate of the polyplexes, which involves endosomal release and DNase resistance, is more important to overall transfection efficiency than barriers to entry, such as polyplex size.

Original languageEnglish
Pages (from-to)1244-1252
Number of pages9
Issue number5
Publication statusPublished - 2009 May 11
Externally publishedYes

ASJC Scopus subject areas

  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry


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