Hui Yue, Wibowo David, Zhao Chun-Xia
Australian Institute for Bioengineering and Nanotechnology, The University of Queensland , St. Lucia QLD 4072, Australia.
Langmuir. 2016 Jan 26;32(3):822-30. doi: 10.1021/acs.langmuir.5b03811. Epub 2016 Jan 11.
We recently developed a novel approach for making oil-core silica-shell nanocapsules using designed bifunctional peptides (also called biomineralizing peptide surfactants) having both surface activity and biomineralization activity. Using the bifunctional peptides, oil-in-water nanoemulsion templates can be readily prepared, followed by the silicification directed exclusively onto the oil droplet surfaces and thus the formation of the silica shell. To explore their roles in the synthesis of silica nanocapsules, two bifunctional peptides, AM1 and SurSi, were systematically studied and compared. Peptide AM1, which was designed as a stimuli-responsive surfactant, demonstrated quick adsorption kinetics with a rapid decrease in the oil-water interfacial tension, thus resulting in the formation of nanoemulsions with a droplet size as small as 38 nm. Additionally, the nanoemulsions showed good stability over 4 weeks because of the formation of a histidine-Zn(2+) interfacial network. In comparison, the SurSi peptide that was designed by modularizing an AM1-like surface-active module with a highly cationic biosilicification-active module was unable to effectively reduce the oil-water interfacial tension because of its high molecular charge at neutral pH. The slow adsorption resulted in the formation of less stable nanoemulsions with a larger size (60 nm) than that of AM1. Besides, both AM1 and SurSi were found to be able to induce biomimetic silica formation. SurSi produced well-dispersed and uniform silica nanospheres in the bulk solution, whereas AM1 generated only irregular silica aggregates. Consequently, well-defined silica nanocapsules were synthesized using SurSi nanoemulsion templates, whereas silica aggregates instead of nanocapsules predominated when templating AM1 nanoemulsions. This finding indicated that the capability of peptide surfactants to form isolated silica nanospheres might play a role in the successful fabrication of silica nanocapsules. This fundamental study provides insights into the design of bifunctional peptides for making silica nanocapsules.
我们最近开发了一种利用具有表面活性和生物矿化活性的设计双功能肽（也称为生物矿化肽表面活性剂）制备油核二氧化硅壳纳米胶囊的新方法。使用双功能肽，可以轻松制备水包油纳米乳液模板，然后将硅化作用专门导向油滴表面，从而形成二氧化硅壳。为了探索它们在二氧化硅纳米胶囊合成中的作用，对两种双功能肽AM1和SurSi进行了系统研究和比较。肽AM1被设计为刺激响应性表面活性剂，表现出快速的吸附动力学，油水界面张力迅速降低，从而形成了液滴尺寸小至38 nm的纳米乳液。此外，由于形成了组氨酸-Zn(2+)界面网络，纳米乳液在4周内表现出良好的稳定性。相比之下，通过将类似AM1的表面活性模块与高度阳离子化的生物硅化活性模块模块化设计的SurSi肽，由于其在中性pH下的高分子电荷，无法有效降低油水界面张力。缓慢的吸附导致形成稳定性较差、尺寸比AM1大（60 nm）的纳米乳液。此外，发现AM1和SurSi都能够诱导仿生二氧化硅的形成。SurSi在本体溶液中产生了分散良好且均匀的二氧化硅纳米球，而AM1只产生了不规则的二氧化硅聚集体。因此，使用SurSi纳米乳液模板合成了明确的二氧化硅纳米胶囊，而以AM1纳米乳液为模板时，主要形成的是二氧化硅聚集体而非纳米胶囊。这一发现表明，肽表面活性剂形成孤立二氧化硅纳米球的能力可能在二氧化硅纳米胶囊的成功制备中发挥作用。这项基础研究为设计用于制备二氧化硅纳米胶囊的双功能肽提供了见解。
