Paramylon hydrogel: A bioactive polysaccharides hydrogel that scavenges ROS and promotes angiogenesis for wound repair.

The excessive inflammation, oxidative stress, and impaired angiogenesis are major factors leading to difficulties in chronic wound healing. To develop bioactive materials with intrinsic antioxidant and anti-inflammatory properties, we prepared hydrogels for the first time using paramylon secreted by Euglena gracilis which is a polysaccharide has been approved by FDA as food additive. Results showed that the paramylon hydrogel has favourable anti-inflammatory effects and the ability to scavenge reactive oxygen species (ROS) through free radical destruction, deoxygenation, and singlet oxygen quenching, and inhibit ROS production by chelating the metal ions required for the formation of ROS. We found that the paramylon hydrogel could effectively reduce wound inflammation and promote angiogenesis to facilitate wound repair. Furthermore, for the first time, we found that paramylon hydrogel could promote the formation of blood vessels via the HIF-1α-VEGF pathway. These results indicated that the highly bioactive paramylon could be the preferred material for wound healing.