Programmed Ephemeral Gels: New Types of Biomaterials

Summary: In various biological processes, a solid gel phase is produced which later dissolves. Similar ephemeral protein gels were obtained in vitro using two antagonistic enzymes, one generating and the other cleaving covalent bonds. Alternate sol/gel and gel/sol transitions should occur within such a system, generating transient gel phases. An experimental system consisting of gelatin, transglutaminase and thermolysin was first tested. The various gels obtained were programmed to dissolve after a determined time, without any change in temperature or medium composition, and constitute a completely new type of material which we term “Enzgels”. Varying temperature, but also the protein nature and concentration, the protease specificity, the ratio of the two antagonistic enzymes and, the activity of each enzyme, we were able to generate a full range of ephemeral gels with controlled life times and mechanistic properties.