Department of Chemistry, Sapienza University of Rome, P. le A. Moro 5, 00185 Rome, Italy.
Department of Chemistry, Sapienza University of Rome, P. le A. Moro 5, 00185 Rome, Italy.
J Colloid Interface Sci. 2019 Oct 15;554:453-462. doi: 10.1016/j.jcis.2019.07.019. Epub 2019 Jul 8.
Sodium Deoxycholate (NaDC) and Phenylalanine (Phe) are important biological hydrogelators. NaDC hydrogels form by lowering the pH or by increasing the ionic strength. Phe gels form from saturated solution by thermal induction and slow kinetics. The resulting gels hold great potential in medicine and biology as drug carriers and models for fundamental self-assembly in pathological conditions. Based on this background it was hypothesized that a Phe substituted NaDC could provide a molecule with expanded gelling ability, merging those of the precursors.
We coupled both building blocks in a zwitterionic derivative bearing a Phe residue at the C3 carbon of NaDC. The specific zwitterionic structure, the concurrent use of Ca ions for the carboxyl group coordination and the pH control generate conditions for the formation of hydrogels. The hydrogels were analyzed by combining UV and circular dichroism spectroscopies, rheology, small angle X-ray scattering and atomic force microscopy.
Hydrogel appearance occurs in conditions that are uncovered in the case of the pure Phe and NaDC: self-standing gels form instantaneously at room temperature, in the 10-12 pH range and down to concentration of 0.17 wt%. Both thixotropic and shake resistant gels can form depending on the derivative concentration. The gels show an uncommon thermal stability in the scanned range of 20-60 °C. The reported system concurrently enriches the hydrogelation properties of two relevant building blocks. We anticipate some potential applications of such gels in materials science where coordination of metal ions can be exploited for templating inorganic nanostructures.
脱氧胆酸钠（NaDC）和苯丙氨酸（Phe）是重要的生物水凝胶剂。通过降低 pH 值或增加离子强度，NaDC 水凝胶形成。Phe 凝胶从饱和溶液通过热诱导和缓慢的动力学形成。所得凝胶在医学和生物学中作为药物载体和病理条件下基本自组装模型具有很大的潜力。基于此背景，假设 Phe 取代的 NaDC 可以提供一种具有扩展凝胶能力的分子，合并前体的凝胶能力。
我们在带有 NaDC 的 C3 碳上的苯丙氨酸残基的两性离子衍生物中连接了这两个构建块。特定的两性离子结构、同时使用 Ca 离子进行羧基配位和 pH 控制为水凝胶的形成创造了条件。通过结合紫外和圆二色性光谱、流变学、小角 X 射线散射和原子力显微镜分析水凝胶。
在纯 Phe 和 NaDC 的情况下未发现水凝胶外观出现的条件下：室温下立即形成自支撑凝胶，在 10-12 pH 范围内，浓度降至 0.17wt%。根据衍生物浓度，可以形成触变和抗摇凝胶。凝胶在 20-60°C 的扫描范围内表现出不寻常的热稳定性。所报道的系统同时丰富了两个相关构建块的水凝胶化性质。我们预计这种凝胶在材料科学中有一些潜在的应用，其中金属离子的配位可以用于模板无机纳米结构。
