title: Stable and pH-sensitive protein nanogels made by self-assembly of heat denatured soy protein.
abstract: In this study, we examined the possibility of preparing stable soy protein nanogels by simply heating homogeneous soy protein dispersion. The protein nanogels formed were characterized by z-average hydrodynamic diameter, polydispersity index, turbidity, ζ-potential, morphology, and their stability to pH and ionic strength change. Soy protein dispersion (1% w/v) was homogeneous around pH 5.9 where it had the lowest polydispersity index (∼0.1). Stable and spherical nanogels were formed by heating soy protein dispersion at pH 5.9 under 95 °C. They sustained constantly low polydispersity index (∼0.1) in the investigated pH range of 6.06-7.0 and 2.6-3.0. The nanogels were pH-sensitive and would swell with pH change. They were stable at 0-200 mM NaCl concentration. Denaturation of soy glycinin was the prerequisite for the formation of stable nanogels. Soy protein nanogels had a core-shell structure with basic polypeptides and β subunits interacting together as the hydrophobic core; and acid polypeptides, α', and α subunits locating outside the core as hydrophilic shell. The inner structure of soy protein nanogels was mainly stabilized by disulfide bonds cross-linked network and hydrophobic interaction. Soy protein nanogels made in this study would be useful as functional ingredients in biotechnological, pharmaceutical, and food industries.
authors.affiliation: College of Light Industry and Food Sciences, and ‡State Key Laboratory of Pulp and Paper Engineering, South China University of Technology , Guangzhou 510640, China.
authors.forename: Nannan
authors.initials: N
authors.lastname: Chen
authors.forename: Lianzhu
authors.initials: L
authors.lastname: Lin
authors.forename: Weizheng
authors.initials: W
authors.lastname: Sun
authors.forename: Mouming
authors.initials: M
authors.lastname: Zhao
mesh_terms: D005916:Globulins / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D000080385:Nanogels; D011092:Polyethylene Glycols / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D011487:Protein Conformation; D055550:Protein Stability; D030262:Soybean Proteins / Q000737:chemistry*; D013025:Glycine max / Q000737:chemistry*
chemical_list: D005916:Globulins; D000080385:Nanogels; D030262:Soybean Proteins; C413692:polyethylene glycol polyethyleneimine nanogel; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; C011474:glycinin
keywords: heating; nanogels; pH-sensitive; soy protein; stable; swell