Structural and dynamical characterization of poly-gamma-glutamic acid-based cross-linked nanoparticles

Judit Éva Fleischer Radu, Levente Novak, John F. Hartmann, Neda Beheshti, Anna Lena Kjøniksen, Bo Nyström, János Borbély

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22 Citations (Scopus)


This work describes the formation of water-soluble hydrophilic nanoparticles from biosynthetic poly-β-glutamic acid (PGA). Nanoparticles were formed by cross-linking using 2,2′-(ethylenedioxy) diethylamine in the presence of water-soluble carbodiimide. The structure was determined by nuclear magnetic resonance spectroscopy and the particle size by transmission electron microscopy (TEM), size exclusion chromatography (SEC), and dynamic light-scattering (DLS) measurements. The results from TEM, SEC, and DLS reveal that the particle size depends on the ratio of cross-linking. Particle size values measured by TEM were between 20 and 90 nm. Formation of cross-linked nanoparticles results in a dramatic viscosity drop compared to the viscosity of the corresponding solution of the parent PGA. The viscosity and DLS experiments disclose an intriguing interplay between intrachain and interchain cross-linking of the polymer chains, depending on the cross-linker density and polymer concentration. The SEC measurements show that the retention time of the major portion of particles increase because of the higher cross-linking ratio. At moderate cross-linker concentration, intramolecular cross-linking is the dominant process, whereas at higher cross-linker densities, the interpolymer cross-linking plays an important role. As a result, large clusters are also formed.

Original languageEnglish
Pages (from-to)365-376
Number of pages12
JournalColloid and Polymer Science
Issue number4
Publication statusPublished - Apr 1 2008



  • Cross-linking
  • DLS
  • Nanoparticles
  • Poly-gamma-glutamic acid
  • Rheology

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Colloid and Surface Chemistry
  • Materials Chemistry

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