Pore sizes in hydrated dextran microspheres

Research output: Contribution to journalArticlepeer-review


  • Robert J H Stenekes
  • Stefaan C. De Smedt
  • Joseph Demeester
  • Wim E. Hennink

Colleges, School and Institutes

External organisations

  • Octoplus Technol
  • Department of Pharmaceutics
  • Utrecht University
  • Ghent University
  • Utrecht Inst. Pharmaceutical Sci.
  • OctoPlus B.V.
  • Lab. Gen. Biochem. and Phys. Pharm.


The average pore size of hydrated dextran microspheres is derived from rheological and protein release data. The microspheres were prepared by cross-linking an aqueous solution of methacrylated dextran emulsified in a continuous poly(ethylene glycol) phase. The rheological data were obtained using a novel micromanipulation technique, which enables the compression of a single microsphere. The so obtained pseudoelasticity moduli of the microspheres were derived from these compression data and corresponded well with the elasticity moduli of macroscopic hydrogels of the same composition, as determined with dynamic mechanical analysis. The modulus increased with decreasing water contents of the microspheres and with increasing degrees of methacrylate substitution of the dextran used. Furthermore, the average pore sizes calculated from the pseudoelasticity moduli were in good agreement with the pore sizes derived from protein release data. In conclusion, this study shows that micromanipulation provides insight into the average pore sizes of dextran microspheres, which is an important characteristic that will modulate the release of encapsulated proteins.


Original languageEnglish
Pages (from-to)696-703
Number of pages8
Issue number4
Publication statusPublished - Dec 2000