title: Influence of free chains on the swelling pressure of PEG-HEMA and dex-HEMA hydrogels.
abstract: Insight in the osmotic behavior of degrading hydrogels is of great importance in the design of biodegradable hydrogels for biomedical applications. This study compares the degradation behavior of PEG-HEMA (hydroxyethylmethacrylated polyethylene glycol) and dex-HEMA (hydroxyethylmethacrylated dextran) hydrogels. The degradation of PEG-HEMA gels takes several months to over a year, while that of dex-HEMA gels takes only days or weeks. The faster degradation kinetics of dex-HEMA networks can be attributed to stabilization of the keto-enol form by hydroxyl groups. Upon degradation of PEG-HEMA and dex-HEMA hydrogels, respectively, free PEG and free dextran chains are produced. We investigated the effect of unattached PEG and dextran chains on the swelling pressure of the degrading gels. It is found that low molecular weight free chains significantly increase the swelling pressure. However, the contribution of higher molecular weight free chains (M(w)>10 kDa) is similar to that of the network chains.
authors.affiliation: Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium.
authors.forename: T G
authors.initials: TG
authors.lastname: Van Thienen
authors.forename: F
authors.initials: F
authors.lastname: Horkay
authors.forename: K
authors.initials: K
authors.lastname: Braeckmans
authors.forename: B G
authors.initials: BG
authors.lastname: Stubbe
authors.forename: J
authors.initials: J
authors.lastname: Demeester
authors.forename: S C
authors.initials: SC
authors.lastname: De Smedt
mesh_terms: D001672:Biocompatible Materials; D003911:Dextrans / Q000138:chemical synthesis*; D004337:Drug Carriers; D020100:Hydrogels; D007700:Kinetics; D008689:Methacrylates / Q000138:chemical synthesis*; D015394:Molecular Structure; D008970:Molecular Weight; D009997:Osmotic Pressure; D011092:Polyethylene Glycols / Q000138:chemical synthesis*; D011109:Polymethacrylic Acids / Q000138:chemical synthesis*; D013678:Technology, Pharmaceutical; D014867:Water / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D003911:Dextrans; D004337:Drug Carriers; D020100:Hydrogels; D008689:Methacrylates; C521570:PEG-HEMA; D011109:Polymethacrylic Acids; C508284:dextran hydroxyethyl methacrylate; D014867:Water; D011092:Polyethylene Glycols