title: Rheological characterization of in situ crosslinkable hydrogels formulated from oxidized dextran and N-carboxyethyl chitosan.
abstract: The gelation kinetics of an in situ gelable hydrogel formulated from oxidized dextran (Odex) and N-carboxyethyl chitosan (CEC) was investigated rheologically. Both Schiff base mediated chemical and physical crosslinking account for its rapid gelation (30-600 s) between 5 and 37 degrees C. The correlation between gelation kinetics and hydrogel properties with Odex/CEC concentration, their feed ratio, and temperature were elucidated. The gelation time determined from crossing over of storage moduli (G') and loss moduli (G' ') was in good agreement with that deduced from frequency sweeping tests according to the Winter-Chambon power law. The power law exponents for a 2% (w/v) Odex/CEC solution (ratio 5:5) at the gel point was 0.61, which is in excellent agreement with the value predicted from percolation theory (2/3). Temperature dependence of gelation time for the same hydrogel formulation is well-described by an Arrhenius plot with its apparent activation energy calculated at 51.9 kJ/mol.
authors.affiliation: Department of Biomedical Engineering, State University of New York-Stony Brook, Stony Brook, New York 11794-8181, USA.
authors.forename: Lihui
authors.initials: L
authors.lastname: Weng
authors.forename: Xuming
authors.initials: X
authors.lastname: Chen
authors.forename: Weiliam
authors.initials: W
authors.lastname: Chen
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D048271:Chitosan / Q000031:analogs & derivatives / Q000737:chemistry*; D003911:Dextrans / Q000138:chemical synthesis / Q000737:chemistry*; D020100:Hydrogels / Q000138:chemical synthesis* / Q000737:chemistry; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D012212:Rheology; D013696:Temperature; D013997:Time Factors
chemical_list: D003911:Dextrans; D020100:Hydrogels; D048271:Chitosan