Mechanistic study of transfection of chitosan/DNA complexes coated by anionic poly(γ-glutamic acid)

Zi Xian Liao, Shu Fen Peng, Yi Cheng Ho, Fwu Long Mi, Barnali Maiti, Hsing Wen Sung

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


Chitosan (CS) has been investigated as a non-viral carrier for gene delivery, but resulting in a relatively low transfection. To address this concern, we developed a ternary system comprised the core of CS/DNA complex and the outer coating of an anionic polymer, poly(γ-glutamic acid) (γ-PGA). In molecular dynamic (MD) simulations, we found that γ-PGA was entangle tightly with the excess CS emanating from the surface of test complexes, thus making them more compact. With γ-PGA coating, the extent of test complexes internalized and their transfection efficiency were evidently enhanced. Trypsin treatment induced a concentration-dependent decrease in internalization of the γ-PGA-coated complexes, suggesting a specific protein-mediated endocytosis. The endocytosis inhibition study indicates that the γ-glutamyl transpeptidase (GGT) present on cell membranes was responsible for the uptake of test complexes. The amine group in the N-terminal γ-glutamyl unit on γ-PGA played an essential role in the interaction with GGT. When entangled with CS, the free N-terminal γ-glutamyl unit of γ-PGA on test complexes was exposed and might thus be accommodated within the γ-glutamyl binding pocket of the membrane GGT. Above results suggest that the γ-PGA coating on CS/DNA complexes can significantly enhance their cellular uptake via a specific GGT-mediated pathway. Knowledge of the uptake mechanism is crucial for the development of an efficient vector for gene transfection.

Original languageEnglish
Pages (from-to)3306-3315
Number of pages10
Issue number11
Publication statusPublished - Apr 2012
Externally publishedYes


  • Gene transfection
  • Poly(γ-glutamic acid)
  • Receptor-mediated endocytosis
  • γ-glutamyl transpeptidase
  • γ-glutamyl unit

ASJC Scopus subject areas

  • Bioengineering
  • Ceramics and Composites
  • Biophysics
  • Biomaterials
  • Mechanics of Materials


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