WestCHEM, Department of Pure & Applied Chemistry, University of Strathclyde , 99 George Street, Glasgow G1 1RD, U.K.
Department of Chemical and Biomolecular Engineering, McCourtney Hall, University of Notre Dame , Notre Dame, Indiana 46556, United States.
ACS Appl Mater Interfaces. 2018 Jan 24;10(3):3069-3075. doi: 10.1021/acsami.7b15456. Epub 2018 Jan 11.
Combining (bio)catalysis and molecular self-assembly provides an effective approach for the production and processing of self-assembled materials by exploiting catalysis to direct the assembly kinetics and hence controlling the formation of ordered nanostructures. Applications of (bio)catalytic self-assembly in biologically interfacing systems and in nanofabrication have recently been reported. Inspired by self-assembly in biological cells, efforts to confine catalysts on flat or patterned surfaces to exert spatial control over molecular gelator generation and nanostructure self-assembly have also emerged. Building on our previous work in the area, we demonstrate in this report the use of enzymes immobilized onto magnetic nanoparticles (NPs) to spatially localize the initiation of peptide self-assembly into nanofibers around NPs. The concept is generalized for both an equilibrium biocatalytic system that forms stable hydrogels and a nonequilibrium system that normally has a preset lifetime. Characterization of the hydrogels shows that self-assembly occurs at the site of enzyme immobilization on the NPs to give rise to gels with a "hub-and-spoke" morphology, where the nanofibers are linked through the enzyme-NP conjugates. This NP-controlled arrangement of self-assembled nanofibers enables both remarkable enhancements in the shear strength of hydrogel systems and a dramatic extension of the hydrogel stability in the nonequilibrium system. We are also able to show that the use of magnetic NPs enables the external control of both the formation of the hydrogel and its overall structure by application of an external magnetic field. We anticipate that the enhanced properties and stimuli-responsiveness of our NP-enzyme system will have applications ranging from nanomaterial fabrication to biomaterials and biosensing.
将（生物）催化和分子自组装结合起来，通过利用催化作用来指导组装动力学，从而控制有序纳米结构的形成，为自组装材料的生产和加工提供了一种有效的方法。（生物）催化自组装在生物界面系统和纳米制造中的应用最近已有报道。受生物细胞内自组装的启发，人们努力将催化剂限制在平坦或图案化的表面上，以对分子凝胶剂的生成和纳米结构自组装进行空间控制，这方面的工作也已经出现。在我们之前在该领域的工作基础上，本报告演示了将固定在磁性纳米颗粒（NPs）上的酶用于在 NPs 周围空间定位肽自组装成纳米纤维的起始位置，从而实现了这一概念。该概念既适用于形成稳定水凝胶的平衡生物催化体系，也适用于具有预设寿命的非平衡体系。对水凝胶的特性分析表明，自组装发生在 NPs 上酶固定的位置，从而产生具有“轮辐”形态的凝胶，其中纳米纤维通过酶-NP 缀合物连接。这种由 NP 控制的自组装纳米纤维排列方式，使水凝胶体系的剪切强度显著提高，并且在非平衡体系中使水凝胶的稳定性显著延长。我们还能够表明，通过施加外部磁场，可以实现对水凝胶的形成及其整体结构的外部控制。我们预计，我们的 NP-酶系统的增强性能和对刺激的响应能力将在纳米材料制造、生物材料和生物传感等领域得到应用。
