Ferreira Sílvia A, Coutinho Paulo J G, Gama Francisco M
IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Minho University, Campus Gualtar 4710-057, Braga, Portugal.
Centre of Physics, Minho University, Campus Gualtar 4710-057, Braga, Portugal.
Materials (Basel). 2011 Mar 25;4(4):601-620. doi: 10.3390/ma4040601.
Self-assembled nanogels made of hydrophobized pullulan were obtained using a versatile, simple, reproducible and low-cost method. In a first reaction pullulan was modified with hydroxyethyl methacrylate or vinyl methacrylate, further modified in the second step with hydrophobic 1-hexadecanethiol, resulting as an amphiphilic material, which self-assembles in water via the hydrophobic interaction among alkyl chains. Structural features, size, shape, surface charge and stability of the nanogels were studied using hydrogen nuclear magnetic resonance, fluorescence spectroscopy, cryo-field emission scanning electron microscopy and dynamic light scattering. Above the critical aggregation concentration spherical polydisperse macromolecular micelles revealed long-term colloidal stability in aqueous medium, with a nearly neutral negative surface charge and mean hydrodynamic diameter in the range 100-400 nm, depending on the polymer degree of substitution. Good size stability was observed when nanogels were exposed to potential destabilizing pH conditions. While the size stability of the nanogel made of pullulan with vinyl methacrylate and more hydrophobic chains grafted was affected by the ionic strength and urea, nanogel made of pullulan with hydroxyethyl methacrylate and fewer hydrophobic chains grafted remained stable.
采用一种通用、简单、可重复且低成本的方法制备了由疏水化普鲁兰多糖制成的自组装纳米凝胶。在第一步反应中，用甲基丙烯酸羟乙酯或甲基丙烯酸乙烯酯对普鲁兰多糖进行改性，第二步再用疏水性的1-十六烷硫醇进一步改性，得到一种两亲性材料，该材料通过烷基链之间的疏水相互作用在水中自组装。利用氢核磁共振、荧光光谱、低温场发射扫描电子显微镜和动态光散射研究了纳米凝胶的结构特征、尺寸、形状、表面电荷和稳定性。在临界聚集浓度以上，球形多分散大分子胶束在水介质中表现出长期的胶体稳定性，表面电荷近中性且为负，平均流体动力学直径在100-400nm范围内，这取决于聚合物的取代度。当纳米凝胶暴露于潜在的不稳定pH条件下时，观察到良好的尺寸稳定性。虽然接枝了甲基丙烯酸乙烯酯和更多疏水链的普鲁兰多糖制成的纳米凝胶的尺寸稳定性受离子强度和尿素的影响，但接枝了甲基丙烯酸羟乙酯和较少疏水链的普鲁兰多糖制成的纳米凝胶仍保持稳定。
