Université de Strasbourg, CNRS, Institut Charles Sadron UPR 22 , 67034 Strasbourg , France.
Institut National de la Santé et de la Recherche Médicale, UMR-S 1121, "Biomatériaux et Bioingénierie" , 67087 Strasbourg , France.
Langmuir. 2019 Aug 20;35(33):10838-10845. doi: 10.1021/acs.langmuir.9b01420. Epub 2019 Aug 6.
Spatial localization of biocatalysts, such as enzymes, has recently proven to be an effective process to direct supramolecular self-assemblies in a spatiotemporal way. In this work, silica nanoparticles (NPs) functionalized covalently by alkaline phosphatase (NPs@AP) induce the localized growth of self-assembled peptide nanofibers from NPs by dephosphorylation of Fmoc-FFY peptides (Fmoc: fluorenylmethyloxycarbonyl; F: phenylalanine; Y: tyrosine; : phosphate group). The fibrillary nanoarchitecture around NPs@AP underpins a homogeneous hydrogel, which unexpectedly undergoes a macroscopic shape change over time. This macroscopic change is due to a phase separation leading to a dense phase (in NPs and nanofibers) in the center of the vial and surrounded by a dilute one, which still contains NPs and peptide self-assemblies. We thus hypothesize that the phase separation is not a syneresis process. Such a change is only observed when the enzymes are localized on the NPs. The dense phase contracts with time until reaching a constant volume after several days. For a given phosphorylated peptide concentration, the dense phase contracts faster when the NPs@AP concentration is increased. For a given NPs@AP concentration, it condenses faster when the peptide concentration increases. We hypothesize that the appearance of a dense phase is not only due to attractive interactions between NPs@AP but also to the strong interactions of self-assembled peptide nanofibers with the enzymes, covalently fixed on the NPs.
生物催化剂（如酶）的空间定位最近被证明是一种有效的方法，可以在时空上定向超分子自组装。在这项工作中，通过碱性磷酸酶（NPs@AP）共价功能化的二氧化硅纳米颗粒（NPs）通过去磷酸化 Fmoc-FFY 肽（Fmoc：芴甲氧羰基；F：苯丙氨酸；Y：酪氨酸；：磷酸基团）诱导自组装肽纳米纤维在 NPs 上的局部生长。NPs@AP 周围的纤维状纳米结构支撑着均匀的水凝胶，出乎意料的是，水凝胶会随着时间的推移发生宏观形状变化。这种宏观变化是由于相分离导致在小瓶中心形成致密相（在 NPs 和纳米纤维中），并被稀相包围，稀相中仍然含有 NPs 和肽自组装体。因此，我们假设相分离不是一个收缩过程。只有当酶定位在 NPs 上时，才会观察到这种变化。致密相随着时间的推移而收缩，几天后达到恒定体积。对于给定的磷酸化肽浓度，当 NPs@AP 浓度增加时，致密相收缩得更快。对于给定的 NPs@AP 浓度，当肽浓度增加时，它凝结得更快。我们假设致密相的出现不仅归因于 NPs@AP 之间的吸引力相互作用，还归因于与酶的强相互作用，酶通过共价固定在 NPs 上。
