Chain and pore-blocking effects on matrix degradation in protein-loaded microgels

Biomacromolecules. 2014 Oct 13;15(10):3671-8. doi: 10.1021/bm5009525. Epub 2014 Aug 29.

Abstract

Factors affecting matrix degradation in protein-loaded microgels were investigated for dextran-based microgels, the sugar-binding protein Concanavalin A (ConA), and the dextran-degrading enzyme Dextranase. For this system, effects of enzyme, protein, and glucose concentrations, as well as pH, were considered. Microgel network degradation was monitored by micromanipulator-assisted light microscopy, whereas enzyme and protein distributions were monitored by confocal microscopy. Results show that Dextranase-mediated microgel degradation increased with increasing enzyme concentration, whereas an increased ConA loading in the dextran microgels caused a concentration-dependent decrease in microgel degradation. In the presence of glucose, competitive release of microgel-bound ConA restored the microgel degradation observed in the absence of ConA. To clarify effects of mass transport limitations, microgel degradation was compared to that of non-cross-linked dextran, demonstrating that ConA limits enzyme substrate access in dextran microgels primarily through pore blocking and induction of pore shrinkage. The experimentally observed effects were qualitatively captured by a modified Michaelis-Menten approach for spherical symmetry, in which network blocking by ConA was included. Taken together, the results demonstrate that matrix degradation of protein-loaded microgels depends sensitively on a number of factors, which need to be considered in the use of microgels in biomedical applications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Concanavalin A / chemistry*
  • Dextranase / chemistry
  • Dextrans / chemistry*
  • Gels / chemistry*
  • Glucose / chemistry*
  • Hydrogen-Ion Concentration
  • Microscopy, Confocal / methods

Substances

  • Dextrans
  • Gels
  • Concanavalin A
  • Dextranase
  • Glucose