title: Rheological characterization of in situ cross-linkable hyaluronan hydrogels.
abstract: This report investigates the rheological properties of cross-linked, thiol-functionalized HA (HA-DTPH) hydrogels prepared by varying the concentration and molecular weight (MW) of the cross-linker, poly(ethylene glycol) diacrylate (PEGDA). Hydrogels were subsequently cured for either short-term (hours) or long-term (days) and subjected to oscillatory shear rheometry (OSR). OSR allows the evaluation and comparison of the shear storage moduli (G'), an index of the total number of effective cross-links formed in the hydrogels. While the oscillatory time sweep monitored the evolution of G' during in situ gelation, the stress and frequency sweeps measured the G' of preformed and subsequently cured hydrogels. From stress sweeps, we found that, for the hydrogels, G' scaled linearly with PEGDA concentration and was independent of its MW. Upon comparison with the classical Flory's theory of elasticity, stress sweep tests on short-term cured hydrogels revealed the simultaneous, but gradual, formation of spontaneous disulfide cross-links in the hydrogels. Results from time and frequency sweeps suggested that the formation of a stable, three-dimensional network depended strictly on PEGDA concentration. Results from the equilibrium swelling of hydrogels concurred with those obtained from oscillatory stress sweeps. Such a detailed rheological characterization of our HA-DTPH-PEGDA hydrogels will aid in the design of biomaterials targeted for biomedical or pharmaceutical purposes, especially in applications involving functional tissue engineering.
authors.affiliation: Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794-8165, USA.
authors.forename: Kaustabh
authors.initials: K
authors.lastname: Ghosh
authors.forename: Xiao Zheng
authors.initials: XZ
authors.lastname: Shu
authors.forename: Robert
authors.initials: R
authors.lastname: Mou
authors.forename: Jack
authors.initials: J
authors.lastname: Lombardi
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Prestwich
authors.forename: Miriam H
authors.initials: MH
authors.lastname: Rafailovich
authors.forename: Richard A F
authors.initials: RA
authors.lastname: Clark
mesh_terms: D003432:Cross-Linking Reagents / Q000494:pharmacology; D004220:Disulfides / Q000737:chemistry; D006820:Hyaluronic Acid / Q000737:chemistry*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry; D008956:Models, Chemical; D009991:Oscillometry; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013438:Sulfhydryl Compounds; D013997:Time Factors; D023822:Tissue Engineering
chemical_list: D003432:Cross-Linking Reagents; D004220:Disulfides; D020100:Hydrogels; D011109:Polymethacrylic Acids; D013438:Sulfhydryl Compounds; C503797:poly(polyethylene glycol methyl ether acrylate-co-polyethylene glycol diacrylate); D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols; D006820:Hyaluronic Acid