title: In vitro and in vivo demonstration of physically and chemically in situ gelling NIPAAm-based copolymer system.
abstract: Poly(NIPAAm-co-hydroxyethylmethacarylate (HEMA)) acrylate and poly(NIPAAm-co-cysteine ethyl ester (CysOEt)) were synthesized and characterized by GPC(gel permeation chromatography), rheology, NMR (nuclear magnetic resonance), and Ellman's method. Upon mixing of these materials in aqueous solution, they formed gels immediately at body temperature owing to temperature-driven physical gelling, and gradually cured by chemical cross-linking through Michael-type addition reactions between thiols and acrylates. The rate of nucleophilic attack in the Michael-type addition reaction was shown to be highly dependent on the mole ratio of thiol to acrylate at neutral pH. Physical and chemical gelation improved the mechanical properties of the materials compared to purely physical gels. In vitro and in vivo results revealed that chemical and physical gels formed stiffer less viscoelastic materials compared to purely physical gels. Physical and chemical gel systems using thermosensitive polymer with acrylates and thermosensitive polymer with thiols showed minimum toxicity.
authors.affiliation: The Harrington Department of Bioengineering , Center for Interventional Biomaterials, Arizona State University, ECG 334, Tempe, AZ 85287-9709, USA.
authors.forename: Bae Hoon
authors.initials: BH
authors.lastname: Lee
authors.forename: Hanin H
authors.initials: HH
authors.lastname: Beart
authors.forename: Vicki
authors.initials: V
authors.lastname: Cheng
authors.forename: Ryan
authors.initials: R
authors.lastname: McLemore
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Robb
authors.forename: Zhanwu
authors.initials: Z
authors.lastname: Cui
authors.forename: Allan
authors.initials: A
authors.lastname: Dovigi
authors.forename: Brent L
authors.initials: BL
authors.lastname: Vernon
mesh_terms: D000178:Acrylamides / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D000180:Acrylic Resins; D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D003545:Cysteine / Q000031:analogs & derivatives / Q000737:chemistry / Q000633:toxicity; D004548:Elasticity; D005260:Female; D005782:Gels; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D011102:Polyhydroxyethyl Methacrylate / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry / Q000633:toxicity; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D014783:Viscosity
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D001672:Biocompatible Materials; D005782:Gels; D011108:Polymers; C512888:poly(N-isopropylacrylamide-co-hydroxyethyl methacrylate-acrylate); C052970:poly-N-isopropylacrylamide; D011102:Polyhydroxyethyl Methacrylate; C031752:ethyl cysteine; D003545:Cysteine