title: Synthesis of carboxymethyl chitin in aqueous solution and its thermo- and pH-sensitive behaviors.
abstract: Homogenous modification of natural chitin offers the advantage of fair structure control. In this work, novel carboxymethyl chitins (CMCHs) with broad range of degree of substitution (DS: 0.035 to 0.74), high degree of acetylation (DA) and little de-polymerization were synthesized homogeneously in aqueous NaOH/urea solution. The simultaneous determination of DA, DS and carboxymethylation fraction at C3 and C6 for these CMCHs was achieved by proton NMR in acidic deuterated aqueous solution for the first time. Due to the good homogeneity, the prepared CMCH-4 with lower DS of carboxymethylation exhibited, for the first time to our knowledge, dual thermo- and pH-sensitive properties. The nontoxic thermo-sensitive polymer systems gel at body temperature (37 °C) in physiological condition, which is very useful as injectable hydrogels for drug delivery and tissue engineering.
authors.affiliation: Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Luojia Hill, Wuhan 430072, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.affiliation: Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Luojia Hill, Wuhan 430072, PR China.
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Luojia Hill, Wuhan 430072, PR China.
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Luojia Hill, Wuhan 430072, PR China.
authors.forename: Renxi
authors.initials: R
authors.lastname: Zhuo
authors.affiliation: Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Luojia Hill, Wuhan 430072, PR China. Electronic address: xljiang@whu.edu.cn.
authors.forename: Xulin
authors.initials: X
authors.lastname: Jiang
mesh_terms: D001831:Body Temperature; D002240:Carbohydrate Sequence; D002470:Cell Survival / Q000187:drug effects; D002686:Chitin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D016503:Drug Delivery Systems; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D012212:Rheology; D012972:Sodium Hydroxide / Q000737:chemistry; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014508:Urea / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D012996:Solutions; D014867:Water; D002686:Chitin; C044872:O-(carboxymethyl)chitin; D012972:Sodium Hydroxide; D014508:Urea
keywords: Carboxymethyl chitin; Homogeneous synthesis; Injectable hydrogel; Proton NMR; Thermo-responsiveness; pH-responsiveness