Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, West 5th, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, West 5th, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan; Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-8-1, Harumicho, Fuchu, Tokyo 183-8538, Japan.
Carbohydr Polym. 2023 Aug 1;313:120883. doi: 10.1016/j.carbpol.2023.120883. Epub 2023 Apr 5.
Bacterial cellulose (BC) pellicles are strong hydrogels composed of nanofibril networks. These hydrogels are considered attractive materials for synthetic biology, in which biological systems or modules are designed with user-defined functions. To develop BC-based materials with tailored mechanical properties, elucidation of the tensile deformation mechanism is essential. Therefore, in this study, BC hydrogels were fluorescently labeled, and the fiber network under tensile deformation was observed in situ using a device for simultaneous confocal laser scanning microscopy and uniaxial tensile deformation. As a result, strain-dependent deformation modes were identified and the generation of stress paths (stress-loaded fiber segments) during deformation was visualized. Furthermore, characteristic relaxation spectra of the nanofiber network were obtained from stress-relaxation measurements, revealing the existence of a first-order relaxation mode at approximately 1 s and higher-order relaxation modes over a long time period of 10-10 s. On this basis, we proposed a tensile deformation model of the BC hydrogel characterized by rearrangements of fiber segments accompanied by cleavage of cross-links. This model is expected to facilitate synthetic biology using BC hydrogels.
细菌纤维素 (BC) 薄膜是由纳米纤维网络组成的强力水凝胶。这些水凝胶被认为是合成生物学中有吸引力的材料，在合成生物学中，生物系统或模块是根据用户定义的功能设计的。为了开发具有定制机械性能的基于 BC 的材料，阐明拉伸变形机制是至关重要的。因此，在这项研究中，BC 水凝胶被荧光标记，并使用同时进行共聚焦激光扫描显微镜和单轴拉伸变形的设备原位观察纤维网络在拉伸变形下的情况。结果，确定了与应变相关的变形模式，并可视化了在变形过程中产生的应力路径（受载纤维段）。此外，通过应力松弛测量获得了纳米纤维网络的特征松弛光谱，揭示了在大约 1 s 处存在一级松弛模式以及在 10-10 s 的长时间内存在更高阶松弛模式。在此基础上，我们提出了一个由纤维段重排伴随着交联断裂的 BC 水凝胶拉伸变形模型。该模型有望促进使用 BC 水凝胶的合成生物学。
