Experimental Characterization and Theoretical Calculations of Responsive Polymeric Systems
Experimental Characterization and Theoretical Calculations of Responsive Polymeric Systems
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发表时间：
2010-09
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通讯作者：
Salim Khouri
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作者：
Salim Khouri
由于其可控的尺寸、低细胞毒性和独特的结构，基于环糊精的假聚轮烷已被开发以涵盖广泛的各种医学和化学工程应用。研究了α-环糊精（α-CD）接枝PEG链段在PAMAM树枝状大分子表面的络合作用，探讨了这种所谓的主客体相互作用的物理性质和驱动力。在pH为10时，一旦α-CD滴定至PAMAM溶液中，α-CD和PEG化的PAMAM之间就发生络合。然而，在pH为2时，在超过约8.0 mM的临界α-CD浓度（C*）之前，未发生结合。纳米结构的尺寸随着α-CD浓度在pH值为2时从0.5至25 mM范围内而增加。从zeta电位测量，它被发现，聚乙二醇化的PAMAM具有正电荷，归因于PAMAM链上的伯胺基团的质子化，赋予静电排斥力的系统。从DLS和SLS研究中观察到，随着α-CD浓度和pH值的增加，复合物的形态从起始形状变为高斯样结构。利用模拟参数估计技术，研究了棒状纤维素微晶（晶须）的动力学和尺寸（长度、直径、平移和扩散系数）。对于L/d比等于17（ROD 17）的杆，实验D和Θ值产生的长度和直径值显示出与实验结果的密切相似性，在1000次迭代之后，百分比误差分别显著降低接近0.22和0.27%。所提出的方法提供了一个合适的和简单的方法来确定棒状纳米颗粒的长度和直径，如纳米晶纤维素。
Due to their controllable size, low cytotoxicity, and unique architecture, cyclodextrin based pseudopolyrotaxanes have been developed to encompass a broad range of diverse medical and chemical engineering applications. The study of complexation between α-cyclodextrin (alfa-CD) grafted PEG segments on the surface of PAMAM dendrimers was carried out to investigate the physical properties and driving force of this so called host guest interaction. At pH of 10, complexation between alfa-CD and PEGylated-PAMAM occurred once alfa-CD was titrated to the PAMAM solution. However, at pH of 2 no binding took place until a critical alfa-CD concentration (C*) of ~ 8.0 mM was exceeded. The size of the nanostructures increased with alfa-CD concentration ranging from 0.5 to 25 mM at pH value of 2. From zeta potential measurements it was found that the PEGylated-PAMAM possessed positive charges, attributed to the protonation of primary amine groups on PAMAM chains that impart electrostatic repulsive forces to the system. As observed from DLS and SLS study at increasing alfa-CD concentration and pH values, the morphology of the complex changed from a start shaped to a Gaussian like structure. The dynamics and dimensions (length, diameter, translation and diffusion coefficients) of rod-like cellulose micro crystallites (whisker) were also investigated using simulated parameter estimation technique. For rod with L/d ratio equal to 17 (ROD 17), experimental D and Θ values produced length and diameter values showing close resemblance to experimental results with a significant reduction in the percentage error approaching 0.22 and 0.27% after 1000 iterations, respectively. The proposed approach provides a suitable and simple method to determine the length and diameter of rod-like nanoparticles, such as nanocrystalline cellulose.