Plasmid DNA-encapsulating liposomes: Effect of a spacer between the cationic head group and hydrophobic moieties of the lipids on gene expression efficiency

Yosuke Obata, Shunsuke Saito, Naoya Takeda, Shinji Takeoka

Research output: Contribution to journalArticle

40 Citations (Scopus)


We have synthesized a series of cationic amino acid-based lipids having a spacer between the cationic head group and hydrophobic moieties and examined the influence of the spacer on a liposome gene delivery system. As a comparable spacer, a hydrophobic spacer with a hydrocarbon chain composed of 0, 3, 5, 7, or 11 carbons, and a hydrophilic spacer with an oxyethylene chain (10 carbon and 3 oxygen molecules) were investigated. Plasmid DNA (pDNA)-encapsulating liposomes were prepared by mixing an ethanol solution of the lipids with an aqueous solution of pDNA. The zeta potentials and cellular uptake efficiency of the cationic liposomes containing each synthetic lipid were almost equivalent. However, the cationic lipids with the hydrophobic spacer were subject to fuse with biomembrane-mimicking liposomes. 1,5-Dihexadecyl-N-lysyl-N-heptyl-l-glutamate, having a seven carbon atom spacer, exhibited the highest fusogenic potential among the synthetic lipids. Increased fusion potential correlated with enhanced gene expression efficiency. By contrast, an oxyethylene chain spacer showed low gene expression efficiency. We conclude that a hydrophobic spacer between the cationic head group and hydrophobic moieties is a key component for improving pDNA delivery.

Original languageEnglish
Pages (from-to)1148-1158
Number of pages11
JournalBiochimica et Biophysica Acta - Biomembranes
Issue number5
Publication statusPublished - 2009 May 1



  • Cationic lipid
  • Encapsulation
  • Gene expression
  • Liposome
  • Plasmid DNA
  • Spacer

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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