TY - JOUR
T1 - In vitro degradation behavior of microspheres based on cross-linked dextran
AU - Vlugt-Wensink, Karin D.F.
AU - Jiang, Xulin
AU - Schotman, Geert
AU - Kruijtzer, Govert
AU - Vredenberg, Arjen
AU - Chung, Jin T.
AU - Zhang, Zhibing
AU - Versluis, Cees
AU - Ramos, Delphine
AU - Verrijk, Ruud
AU - Jiskoot, Wim
AU - Crommelin, Daan J.A.
AU - Hennink, Wim E.
PY - 2006/11/1
Y1 - 2006/11/1
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=33845992566&partnerID=8YFLogxK
U2 - 10.1021/bm060385z
DO - 10.1021/bm060385z
M3 - Article
C2 - 17096522
AN - SCOPUS:33845992566
SN - 1525-7797
VL - 7
SP - 2983
EP - 2990
JO - Biomacromolecules
JF - Biomacromolecules
IS - 11
ER -