Regeneration of tissues that have lost their function due to disease or aging requires a scaffold that serves as a base for cell colonization and proliferation.However, biologically derived scaffold materials carry the risk of foreign body reactions and infections, while artificially synthesized materials have a lower biocompatibility and are difficult for cells to colonize.

　The research group has developed a gel (hydrogel) material consisting of 99% water and 1% synthetic polymer PEG by utilizing the newly discovered phenomenon of ``gel-gel phase separation.'' "Gel-gel phase separation" is a phenomenon in which a homogeneous gel with a water content of 99% separates into two phases: a thick gel (with a dense network) and a dilute gel (with a loose network).

　Until now, PEG has been considered to be hydrophilic and have poor cell adhesion properties.However, the PEG gel that underwent gel-gel phase separation had a sponge-like structure and contained 99% water, but showed hydrophobic properties that repelled water like oil.The counterintuitive result was that the higher the water content, the more pronounced the degree of gel-gel phase separation, and the less compatible it is with water.In an experiment in which this material was implanted subcutaneously in a model animal, cells invaded from the surrounding area and adipose tissue containing blood vessels was formed.This dramatically expanded the potential of PEG gel as a tissue regeneration scaffold material.

　Diseases such as chronic wounds and diabetic foot ulcers significantly reduce patients' quality of life (QOL) and increase treatment costs.The research group believes that the application of the newly discovered gel material will lead to major advances in treatment methods for these diseases.

Paper information:[Nature Materials] Percolation-induced gel–gel phase separation in a dilute polymer network