title: Structure formation in pH-sensitive hydrogels composed of sodium caseinate and N,O-carboxymethyl chitosan.
abstract: The pH-sensitive hydrogels composed of sodium caseinate (SC) and N,O-carboxymethyl chitosan (NOCC) were prepared and a new method to characterize the gelation process was presented in this work. Reological tests suggested that RSC/NOCC=3/7 (the weight ratio of SC and NOCC) was the best ratio of hydrogel. The well-developed three-dimensional network structures in the hydrogel were confirmed by AFM. Two structural parameters, tIS and tCS, denoted as the initial and critical structure formation time, respectively, were used to provide an exact determination of the start of structure formation and description of gelation process. The gelation process strongly depended on temperature changes, a high temperature resulted in an early start of gelation. The non-kinetic model suggested the higher activation energy in the higher temperatures was disadvantageous to structure formation, and vice versa. Due to the smart gel reported here was very stable at room temperature, we believed that the gel is required for applications in drug delivery or could be exploited in the development of potential application as molecular switches in the future.
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Wei
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Xie
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Lin
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, China; College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Fengxia
authors.initials: F
authors.lastname: Wang
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Wanfu
authors.initials: W
authors.lastname: Liang
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, China; College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China. Electronic address: melody_wyx@126.com.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhang
mesh_terms: D002364:Caseins / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D004337:Drug Carriers; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D044367:Phase Transition; D012212:Rheology; D013499:Surface Properties; D013696:Temperature; D013816:Thermodynamics
chemical_list: D002364:Caseins; D004337:Drug Carriers; D020100:Hydrogels; C077199:O,N-carboxymethylchitosan; D048271:Chitosan
keywords: Gelation kinetics; N,O-carboxymethyl chitosan; Sodium caseinate; Sol-gel transition; Structure formation