Department of Physics, Campus Las Lagunillas, University of Jaén, 23071, Jaén, Spain.
Langmuir. 2011 May 17;27(10):6426-32. doi: 10.1021/la2009144. Epub 2011 Apr 20.
The synthesis of composite nanoparticles consisting of a magnetite core coated with a layer of the hormone insulin growth factor 1 (IGF-1) is described. The adsorption of the hormone in the different formulations is first studied by electrophoretic mobility measurements as a function of pH, ionic strength, and time. Because of the permeable character expected for both citrate and IGF-1 coatings surrounding the magnetite cores, an appropriate analysis of their electrophoretic mobility must be addressed. Recent developments of electrokinetic theories for particles covered by soft surface layers have rendered possible the evaluation of the softness degree from raw electrophoretic mobility data. In the present contribution, the data are quantitatively analyzed based on the theoretical model of the electrokinetics of soft particles. As a result, information is obtained on both the thickness and the charge density of the surrounding layer. It is shown that IGF-1 adsorbs onto the surface of citrate-coated magnetite nanoparticles, and adsorption is confirmed by dot-blot analysis. In addition, it is also demonstrated that the external layer of IGF-1 exerts a shielding effect on the surface charge of citrate-magnetite particles, as suggested by the mobility reduction upon contacting the particles with the hormone. Aging effects are demonstrated, providing an electrokinetic fingerprint of changes in adsorbed protein configuration with time.
描述了由磁铁矿核涂覆有一层胰岛素生长因子 1（IGF-1）的复合纳米粒子的合成。首先通过电泳迁移率测量研究了激素在不同配方中的吸附，作为 pH、离子强度和时间的函数。由于预期围绕磁铁矿核心的柠檬酸和 IGF-1 涂层具有可渗透的特性，因此必须对其电泳迁移率进行适当的分析。最近对覆盖有软表面层的粒子的动电学理论的发展使得可以从原始电泳迁移率数据评估软度。在本贡献中，根据软粒子动电学的理论模型对数据进行了定量分析。结果，获得了有关周围层的厚度和电荷密度的信息。结果表明 IGF-1 吸附在柠檬酸涂覆的磁铁矿纳米粒子的表面上，并且通过斑点印迹分析进行了吸附的确认。此外，还证明了 IGF-1 外层对柠檬酸-磁铁矿粒子的表面电荷具有屏蔽作用，这正如与激素接触时迁移率降低所表明的那样。证明了老化效应，提供了随时间变化的吸附蛋白质构象变化的动电指纹。
