title: Synthesis and characterization of amphiphatic carboxymethyl-hexanoyl chitosan hydrogel: water-retention ability and drug encapsulation.
abstract: Carboxymethyl-hexanoyl chitosan (NOCHC) amphiphatic hydrogel with excellent water-absorption and water-retention abilities under neutral conditions was successfully synthesized for the first time and then employed as a carrier for delivering amphiphatic agents. NOCHC is a water-soluble chitosan derivative bearing the carboxymethyl (hydrophilic) group and the hexanoyl (hydrophobic) group, which was synthesized using N,O-carboxymethyl chitosan (NOCC) as the starting precursor. Water-absorption ability (W(c)), water-retention ability, and drug encapsulation efficiency of the NOCHC hydrogel were investigated in terms of the degree of carboxymethyl and hexanoyl substitution. It was found that the amount of moisture uptake was dependent on the relative humidity as well as degree and nature of such substitution. The hexanoyl substitution affected significantly the water-absorption ability by altering the number of water-binding sites and the state of water under low humidity and the fully swollen state, respectively. In addition, the presence of hydrophobic hexanoyl substitution significantly retards water mobility during deswelling, causing better water-retention ability. Moreover, compared with that of pristine chitosan and NOCC, the encapsulation efficiency of ibuprofen (partially hydrophobic agent) was significantly enhanced with the incorporation of the hexanoyl group. These results demonstrate that the newly developed NOCHC amphiphatic hydrogel showed enhanced water-absorption ability, water-retention ability, and amphiphatic drug encapsulation efficiency compared with NOCC and chitosan.
authors.affiliation: Department of Materials Science and Engineering, National Chiao Tung University, 1001 Ta-hsueh Road, Hsinchu, Taiwan, Republic of China.
authors.forename: Tse-Ying
authors.initials: TY
authors.lastname: Liu
authors.forename: San-Yuan
authors.initials: SY
authors.lastname: Chen
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Lin
authors.forename: Dean-Mo
authors.initials: DM
authors.lastname: Liu
mesh_terms: D002152:Calorimetry, Differential Scanning; D002214:Capsules; D048271:Chitosan / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D004337:Drug Carriers / Q000737:chemistry*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000138:chemical synthesis* / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D002214:Capsules; D004337:Drug Carriers; C522410:carboxymethyl-hexanoyl chitosan; D014867:Water; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D048271:Chitosan