title: Enzymatically crosslinked silk-hyaluronic acid hydrogels.
abstract: In this study, silk fibroin and hyaluronic acid (HA) were enzymatically crosslinked to form biocompatible composite hydrogels with tunable mechanical properties similar to that of native tissues. The formation of di-tyrosine crosslinks between silk fibroin proteins via horseradish peroxidase has resulted in a highly elastic hydrogel but exhibits time-dependent stiffening related to silk self-assembly and crystallization. Utilizing the same method of crosslinking, tyramine-substituted HA forms hydrophilic and bioactive hydrogels that tend to have limited mechanics and degrade rapidly. To address the limitations of these singular component scaffolds, HA was covalently crosslinked with silk, forming a composite hydrogel that exhibited both mechanical integrity and hydrophilicity. The composite hydrogels were assessed using unconfined compression and infrared spectroscopy to reveal of the physical properties over time in relation to polymer concentration. In addition, the hydrogels were characterized by enzymatic degradation and for cytotoxicity. Results showed that increasing HA concentration, decreased gelation time, increased degradation rate, and reduced changes that were observed over time in mechanics, water retention, and crystallization. These hydrogel composites provide a biologically relevant system with controllable temporal stiffening and elasticity, thus offering enhanced tunable scaffolds for short or long term applications in tissue engineering.
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA.
authors.forename: Nicole R
authors.initials: NR
authors.lastname: Raia
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA.
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Partlow
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA.
authors.forename: Meghan
authors.initials: M
authors.lastname: McGill
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA.
authors.forename: Erica Palma
authors.initials: EP
authors.lastname: Kimmerling
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA.
authors.forename: Chiara E
authors.initials: CE
authors.lastname: Ghezzi
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA. Electronic address: david.kaplan@tufts.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Kaplan
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D012831:Bombyx / Q000737:chemistry; D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000737:chemistry; D004548:Elasticity; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000166:cytology; D012212:Rheology; D047011:Silk / Q000737:chemistry*; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D020100:Hydrogels; D047011:Silk; D006820:Hyaluronic Acid
keywords: Biomaterials; Enzymatic crosslinking; Hydrogel blends; Polymer composites; Temporal stiffening