- Ryuji Kiyama Graduate School of Life Science, Hokkaido University ,
- Takayuki Nonoyama Faculty of Advanced Life Science, Hokkaido University ,
- Sedlacik Tomas Faculty of Advanced Life Science, Hokkaido University ,
- Hiroshi Jinnai Institute of Multidisciplinary Research for Advanced Materials, Tohoku University ,
- Jian Ping Gong Faculty of Advanced Life Science, Hokkaido University
Hydrogels are promising materials for several applications, including cell scaffolds and artificial load-bearing substitutes (cartilages, ligaments, tendons, etc.). Direct observation of the nanoscale polymer network of hydrogels is essential in understanding its properties. However, imaging of individual network strands at the molecular level is not achieved yet due to the lack of suitable methods. Herein, for the first time, we developed a novel mineral-staining method and network fixation method for transmission electron microscopy observation to visualize the hydrogel network in its unperturbed conformation with nanometer resolution. Surface network observation indicates that the length of surface dangling chains, which play a major role in friction and wetting, can be estimated from the gel mesh size. Moreover, bulk observations reveals a hierarchical formation mechanism of gel heterogeneity. These observations have the great potential to advance gel science by providing comprehensive perspective that link bulk gel properties with nanoscale.