title: Stimuli sensitive super-macroporous cryogels based on photo-crosslinked 2-hydroxyethylcellulose and chitosan.
abstract: Original pH sensitive cryogels, based on two biodegradable natural polymers chitosan (CS) and 2-hydroxyethylcellulose (HEC), were obtained via cryogenic treatment of semi-dilute aqueous solutions and UV induced crosslinking in frozen state. H₂O₂ and N,N'-methylenebisacrylamide (BisAAm) were used as photoinitiator and crosslinking agent, respectively. BisAAm facilitated the formation of polymer co-network and increased both the gel fraction yield and mechanical strength of cryogels. The influence of chitosan content on the physico-mechanical properties of HEC-CS cryogels was investigated. In general, the increase of CS fraction in the polymer co-network increased the degree of swelling and enhanced significantly the storage modulus of materials. All HEC-CS cryogels obtained were opalescent sponge-like materials, which quickly release/uptake water due to their open porous structure. The incorporation of CS provided pH dependent swelling and good bioadhesive properties of cryogels. HEC-CS cryogels were further exploited as drug delivery systems of the highly water soluble drug metronidazole belonging to BCS Class l.
authors.affiliation: Institute of Polymers, Bulgarian Academy of Sciences, Akad. G. Bonchev Street 103A, 1113 Sofia, Bulgaria.
authors.forename: Veselina
authors.initials: V
authors.lastname: Stoyneva
authors.forename: Denitsa
authors.initials: D
authors.lastname: Momekova
authors.forename: Bistra
authors.initials: B
authors.lastname: Kostova
authors.forename: Petar
authors.initials: P
authors.lastname: Petrov
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D059985:Cryogels / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry* / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008795:Metronidazole / Q000737:chemistry; D016062:Porosity; D012212:Rheology; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry*
chemical_list: D000178:Acrylamides; D003432:Cross-Linking Reagents; D059985:Cryogels; D004337:Drug Carriers; D014867:Water; D008795:Metronidazole; D002482:Cellulose; C002283:hydroxyethylcellulose; D048271:Chitosan; D006861:Hydrogen Peroxide; C021221:N,N'-methylenebisacrylamide
keywords: 2-Hydroxyethylcellulose; Chitosan; Cryogels; Drug delivery systems; Metronidazole; Photo-crosslinking