title: Injectable and microporous scaffold of densely-packed, growth factor-encapsulating chitosan microgels.
abstract: In this work, an emulsion crosslinking method was developed to produce chitosan-genipin microgels which acted as an injectable and microporous scaffold. Chitosan was characterized with respect to pH by light scattering and aqueous titration. Microgels were characterized with swelling, light scattering, and rheometry of densely-packed microgel solutions. The results suggest that as chitosan becomes increasingly deprotonated above the pKa, repulsive forces diminish and intermolecular attractions cause pH-responsive chain aggregation; leading to microgel-microgel aggregation as well. The microgels with the most chitosan and least cross-linker showed the highest yield stress and a storage modulus of 16kPa when condensed as a microgel paste at pH 7.4. Two oppositely-charged growth factors could be encapsulated into the microgels and endothelial cells were able to proliferate into the 3D microgel scaffold. This work motivates further research on the applications of the chitosan microgel scaffold as an injectable and microporous scaffold in regenerative medicine.
authors: Department of Chemical & Biological Engineering, Colorado School of Mines, 1613 Illinois Street, Golden, CO 80401, United States. Electronic address: mriedere@mines.edu.
authors: Michael S
authors: MS
authors: Riederer
authors: Department of Chemical & Biological Engineering, Colorado School of Mines, 1613 Illinois Street, Golden, CO 80401, United States. Electronic address: brequist@mines.edu.
authors: Brennan D
authors: BD
authors: Requist
authors: Department of Orthopedics, University of Colorado Anschutz Medical Campus, 12800 E. 19th Avenue, Aurora, CO 80045, United States. Electronic address: Karin.payne@ucdenver.edu.
authors: Karin A
authors: KA
authors: Payne
authors: Department of Chemical & Biological Engineering, Colorado School of Mines, 1613 Illinois Street, Golden, CO 80401, United States. Electronic address: dway@mines.edu.
authors: J Douglas
authors: JD
authors: Way
authors: Department of Chemical & Biological Engineering, Colorado School of Mines, 1613 Illinois Street, Golden, CO 80401, United States. Electronic address: mdkrebs@mines.edu.
authors: Melissa D
authors: MD
authors: Krebs
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D016503:Drug Delivery Systems / Q000379:methods*; D005782:Gels; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009113:Muramidase / Q000737:chemistry*; D042461:Vascular Endothelial Growth Factor A / Q000737:chemistry*
chemical_list: D005782:Gels; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D048271:Chitosan; D009113:Muramidase
keywords: Chitosan; Injectable; Microgel; Regenerative medicine; Scaffold