Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816, USA.
NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA.
Molecules. 2019 Mar 1;24(5):868. doi: 10.3390/molecules24050868.
Polyelectrolyte complexation is a versatile platform for the design of self-assembled materials. Here we use rational design to create ionic hydrophobically-patterned peptides that allow us to precisely explore the role of hydrophobicity on electrostatic self-assembly. Polycations and polyanions were designed and synthesized with an alternating sequence of d- and l-chiral patterns of lysine or glutamic acid with either glycine, alanine or leucine due to their increasing hydrophobicity index, respectively. Two motifs were considered for the oppositely charged patterned peptides; one with equal residues of charged and uncharged amino acids and the other with increased charge density. Mass spectroscopy, circular dichroism, H- and F-NMR spectroscopy were used to characterize the polypeptides. Polyelectrolyte complexes (PECs) formed using the sequences were characterized using turbidity measurements, optical microscopy and infrared spectroscopy. Our results show that the critical salt concentration, a key measure of PEC stability, increased with both increasing charge density as well as hydrophobicity. Furthermore, by increasing the hydrophobicity, the amount of PEC formed increased with temperature, contrary to purely ionic PECs. Lastly, we assessed the encapsulation behavior of these materials using a hydrophobic dye. Concluding that encapsulation efficiency increased with hydrophobic content of the complexes providing insight for future work on the application of these materials for drug delivery.
聚电解质络合是设计自组装材料的一种通用平台。在这里，我们通过合理的设计来创建离子性疏水图案化肽，从而可以精确地探索疏水性对静电自组装的作用。聚阳离子和聚阴离子通过赖氨酸或谷氨酸的 d-和 l-手性图案与甘氨酸、丙氨酸或亮氨酸的交替序列进行设计和合成，这是由于它们的疏水性指数分别增加。对于带相反电荷的图案化肽，考虑了两种基序；一种是带电荷和不带电荷的氨基酸的比例相等，另一种是带电荷密度增加。使用质谱、圆二色性、H 和 F-NMR 光谱对多肽进行了表征。使用浊度测量、光学显微镜和红外光谱对使用这些序列形成的聚电解质复合物（PEC）进行了表征。我们的结果表明，临界盐浓度（PEC 稳定性的关键衡量标准）随着电荷密度和疏水性的增加而增加。此外，通过增加疏水性，形成的 PEC 量随温度增加而增加，这与纯离子 PEC 相反。最后，我们使用疏水性染料评估了这些材料的包封行为。得出的结论是，包封效率随复合物的疏水性含量增加而增加，这为今后这些材料在药物输送中的应用提供了参考。
