title: Characterization of different substituted carboxymethyl starch microgels and their interactions with lysozyme.
abstract: A carboxymethyl starch (CMS) microgel system was prepared for the control of uptaking and releasing proteins (lysozyme). The physicochemical properties of microgels in various degrees of substitution (DS) were determined by thermal gravimetric analysis (TGA), swelling degree, and rheological analysis. The microgel particle size mostly ranged from 25 µm to 45 µm. The result obtained from the TGA studies indicated that carboxymethylation decreased the thermal stability of starch, but crosslinking increased the thermal stability of CMS. The CMS microgels showed typical pH sensitivity, and the swelling degree of microgel increased with the increasing of DS and pH, because of the large amounts of carboxyl group ionization. The samples (2.25%) could behave as viscoelastic solids since the storage modulus was larger than the loss modulus over the entire frequency range. The protein uptake increased with increasing pH and DS at low salt concentration. The optimal pH shifted to lower pH with increasing ionic strength. The saturated protein uptake decreased with increasing ionic strength at each pH. The protein was easily released from the microgel with high pH and high salt concentration.
authors.affiliation: The State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China; School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Bao
authors.initials: B
authors.lastname: Zhang
authors.affiliation: School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Han
authors.initials: H
authors.lastname: Tao
authors.affiliation: The State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China; School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Benxi
authors.initials: B
authors.lastname: Wei
authors.affiliation: The State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China; School of Food Science and Technology, Jiangnan University, Wuxi, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China.
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Jin
authors.affiliation: School of Food Science and Technology, Jiangnan University, Wuxi, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China.
authors.forename: Xueming
authors.initials: X
authors.lastname: Xu
authors.affiliation: The State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Yaoqi
authors.initials: Y
authors.lastname: Tian
mesh_terms: D005782:Gels / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009113:Muramidase / Q000737:chemistry*; D009994:Osmolar Concentration; D010316:Particle Size; D011506:Proteins / Q000737:chemistry; D013213:Starch / Q000031:analogs & derivatives* / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D005782:Gels; D011506:Proteins; D013213:Starch; C034848:carboxymethyl starch; D009113:Muramidase