Tissues such as human skin are multicomponent and hierarchical, mechanically heterogeneous and anisotropic, self-healing, impact-absorbing, and dynamically responsive (Fig. 1A). Traditional synthetic materials, on the other hand, do not typically possess such multiscale and dynamic responsiveness. Despite extensive efforts in the biomimetics field to develop extracellular matrix (ECM)-like synthetic polymeric networks, an artificial tissue-like material that can concurrently mimic dynamic cellular- and ECM-level behaviours has yet been achieved. One major challenge is to develop cell-like building blocks that can display dynamic responses that are in synergy with the existing ECM-like polymer platforms.
In collaboration with Professor Jaeger from the University of Chicago, the Tian lab proposed that hydrated and cellular-scale granular materials can enable multiscale tissue-like behaviours in synthetic materials (Fig. 1). Due to strong intergranular interactions, dense suspensions of granular materials dynamically respond to external stress through rapid phase transformations. When integrated with synthetic hydrogel networks, the grain-embedded composite may be considered an analogue of biological tissue in terms of both structures (hierarchical assembly of cell and ECM) and properties (such as dynamic responsiveness and remodelling, and memory effect) (Fig. 1B). Using several synchrotron-based X-ray techniques, we revealed the mechanically-induced organization and training dynamics of the starch granules in the hydrogel matrix. These dynamic behaviours enable multiple tissue-like properties such as programmability, anisotropy, strain-stiffening, mechanochemistry, and self-healability. Preliminary results in my lab (manuscript in preparation) show that these tissue-like materials can significantly improve precision and biocompatibility, and bioelectronic recording, during animal surgery with a robotic device.
Figure 1. Tissue-like materials made from starch granules and hydrogels. (A) Living tissues have unique properties. (B) Granular materials can serve as a cell-like component in the hydrogel composite to enable tissue-like properties. (C) Cryo-SEM image showing the granule-hydrogel interface. (D-E) X-ray tomography images of the granules.
- Y. Fang, E. Han, X.-X. Zhang, Y. W. Jiang, Y. L. Lin, J. Y. Shi, J. B. Wu, L. Y. Meng, X. Gao, P. J. Griffin, X. H. Xiao, H.-M. Tsai, H. Zhou, X. B. Zuo, Q. Zhang, M. Q. Chu, Q. T. Zhang, Y. Gao, L. K. Roth, R. Bleher, Z. Y. Ma, Z. Jiang, J. P. Yue, C.-M. Kao, C.-T. Chen, A. Tokmakoff, J. Wang, H. M. Jaeger, B. Z. Tian, Dynamic and programmable cellular-scale granules enable tissue-like materials. Matter, 2020, 2, 948-964. Link
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