In vitro degradation behavior of microspheres based on cross-linked dextran

Research output: Contribution to journalArticlepeer-review

Authors

  • Karin D.F. Vlugt-Wensink
  • Xulin Jiang
  • Geert Schotman
  • Govert Kruijtzer
  • Arjen Vredenberg
  • Jin T. Chung
  • Cees Versluis
  • Delphine Ramos
  • Ruud Verrijk
  • Wim Jiskoot
  • Daan J.A. Crommelin
  • Wim E. Hennink

Colleges, School and Institutes

External organisations

  • Utrecht University
  • Octoplus Technol
  • Debye Institute
  • Centre for Formulation Engineering Chemical Engineering
  • Leiden/Amsterdam Center for Drug Research

Abstract

The aim of this study was to investigate the in vitro degradation of hydroxyl ethyl methacrylated dextran (dex-HEMA) microspheres. Dextran microspheres were incubated in phosphate buffer pH 7.4 at 37 °C, and the dry mass, mechanical strength, and chemical composition of the microspheres were monitored in time. The amount and nature of the formed degradation products were established for microspheres with different cross-fink densities by FT-IR (Fourier transformed infrared spectroscopy), NMR, mass spectrometry, SEC analysis, and XPS (X-ray photoelectron microscopy). The dex-HEMA microspheres DS 12 (degree of HEMA substitution; the number of HEMA groups per 100 glucose units) incubated at pH 7.4 and 37 °C showed a continuous mass loss, leaving after 6 months a residue of about 10% (w/w) of water-insoluble products. NMR, mass spectrometry, and SEC showed that the water-soluble degradation products consisted of dextran, low molecular weight pHEMA (Mn ≈ 15 kg/mol), and small amounts of unreacted HEMA and HEMA-DMAP (intermediate reaction product of the Baylis-Hillman reaction of HEMA with DMAP (4-dimethyl aminopyridine)). Microscopy revealed that the water-insoluble residue consisted of particles with shape and size similar to that of nondegraded microspheres. However, these particles had lost their mechanical strength as evidenced from micromanipulation experiments. FT-IR and XPS (X-ray photoelectron microscopy) revealed that these particles consisted of pHEMA, of which a small fraction was soluble in methanol (Mn ranging between 27 and 82 kg/mol). The insoluble material likely consisted of lightly cross-linked pHEMA. In conclusion, in vitro degradation of dex-HEMA microspheres results in the formation of water-soluble degradation products (mainly dextran), leaving a small water-insoluble residue mainly consisting of pHEMA.

Details

Original languageEnglish
Pages (from-to)2983-2990
Number of pages8
JournalBiomacromolecules
Volume7
Issue number11
Publication statusPublished - 1 Nov 2006