Hu Jinhua, Yu Shaoyong, Yao Ping
The Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science, Fudan University, Shanghai 200433, China.
Langmuir. 2007 May 22;23(11):6358-64. doi: 10.1021/la063419x. Epub 2007 Apr 18.
Ovalbumin and ovotransferrin are two proteins in hen egg white with isoelectric points of 4.8 and 6.8, respectively. A convenient and green method was developed in this study to prepare ovalbumin-ovotransferrin nanogels: a mixture of the two proteins was adjusted to a certain pH and then heated. Heat induced denaturation and gelation of the proteins, but the negative charges of ovalbumin prevented the proteins from coagulating. Dynamic light scattering, transmission electron microscopy, and atomic force microscopy studies reveal the nanogels have a spherical shape in both the swell and dry forms. Their apparent hydrodynamic diameters are in the range of 100-220 nm depending on the protein concentration in the nanogel preparation process. The nanogels display an amphoteric property: they carry net positive charges at pH lower than 5.5 and net negative charges at pH higher than 5.5. They form redispersible secondary aggregates at pH 5.0-6.0. The nanogels are stable in the pH ranges of 2.0-4.0 and 7.0-11.0, and they exhibit pH unchangeable but thermoreversible hydrophobicity. Benzoic acid was used as a model drug to study the loading ability. The native ovalbumin and ovotransferrin cannot bind with benzoic acid, whereas the nanogels with the network structure and hydrophobic binding sites can load benzoic acid through hydrophobic and electrostatic interactions.
卵清蛋白和卵转铁蛋白是鸡蛋清中的两种蛋白质，其等电点分别为4.8和6.8。本研究开发了一种简便且绿色的方法来制备卵清蛋白-卵转铁蛋白纳米凝胶：将这两种蛋白质的混合物调节至特定pH值后加热。加热导致蛋白质变性和凝胶化，但卵清蛋白的负电荷阻止了蛋白质凝聚。动态光散射、透射电子显微镜和原子力显微镜研究表明，纳米凝胶在膨胀和干燥形式下均呈球形。根据纳米凝胶制备过程中蛋白质的浓度，其表观流体动力学直径在100-220nm范围内。纳米凝胶具有两性性质：在pH低于5.5时带净正电荷，在pH高于5.5时带净负电荷。它们在pH 5.0-6.0时形成可再分散的二级聚集体。纳米凝胶在pH 2.0-4.0和7.0-11.0范围内稳定，并且表现出pH不变但热可逆的疏水性。以苯甲酸为模型药物研究其负载能力。天然的卵清蛋白和卵转铁蛋白不能与苯甲酸结合，而具有网络结构和疏水结合位点的纳米凝胶可以通过疏水和静电相互作用负载苯甲酸。
