2019 Volume 47 Issue 2 Pages 55-59
In a previous study (Sakai A., et al., ACS Cent. Sci., 4, 477 (2018)), a spherical microgel of gelatin prepared inside a lipid droplet was reported to have a higher surface elasticity than the bulk gel. In this study, we investigate the role of contact or lack of contact between gelatin and the lipid membrane as well as the micrometric confinement to isolate the dominant cause of this higher elasticity of microgels. For our experiment, we prepared a concave microgel of gelatin with two surfaces, with one surface in contact with the lipid membrane and the other without being in contact with the membrane. Next, we measured the elasticities of both the surfaces by using micropipette aspiration. Although the elasticity of the surface not in contact with the lipid membrane was slightly lower than that of the surface in contact with the membrane, the elasticity value was much higher than that for the bulk gel. Further, it was found that the droplet confinement without lipids did not decrease the elasticity of gelatin microgels. These results demonstrate that the dominant factor responsible for the higher elasticity of gelatin microgels is micrometric confinement and not their contact with the lipid membrane.
