Enzyme-mediated fast in situ formation of hydrogels from dextran-tyramine conjugates

Biomaterials. 2007 Jun;28(18):2791-800. doi: 10.1016/j.biomaterials.2007.02.032. Epub 2007 Feb 25.


Dextran hydrogels were formed in situ by enzymatic crosslinking of dextran-tyramine conjugates and their mechanical, swelling and degradation properties were evaluated. Two types of dextran-tyramine conjugates (M(n,dextran)=14k, M(w)/M(n)=1.45), i.e. dextran-tyramine linked by a urethane bond (denoted as Dex-TA) or by an ester-containing diglycolic group (denoted as Dex-DG-TA), with different degrees of substitution (DS) were prepared. Hydrogels were rapidly formed under physiological conditions from Dex-TA DS 10 or 15 and Dex-DG-TA DS 10 at or above a concentration of 2.5 wt% in the presence of H(2)O(2) and horseradish peroxidase (HRP). The gelation time ranged from 5s to 9 min depending on the polymer concentration and HRP/TA and H(2)O(2)/TA ratios. Rheological analysis showed that these hydrogels are highly elastic. The storage modulus (G'), which varied from 3 to 41 kPa, increased with increasing polymer concentration, increasing HRP/TA ratio and decreasing H(2)O(2)/TA ratio. The swelling/degradation studies showed that under physiological conditions, Dex-TA hydrogels are rather stable with less than 25% loss of gel weight in 5 months, whereas Dex-DG-TA hydrogels are completely degraded within 4-10d. These results demonstrate that enzymatic crosslinking is an efficient way to obtain fast in situ formation of hydrogels. These dextran-based hydrogels are promising for use as injectable systems for biomedical applications including tissue engineering and protein delivery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cross-Linking Reagents / chemistry
  • Dextrans / chemical synthesis
  • Dextrans / chemistry*
  • Hydrogels / chemical synthesis
  • Hydrogels / chemistry*
  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Tyramine / chemical synthesis
  • Tyramine / chemistry*


  • Cross-Linking Reagents
  • Dextrans
  • Hydrogels
  • Tyramine