Shear recovery and temperature stability of Ca2+ and Ag+ glycolipid fibrillar metallogels with unusual β-sheet-like domains

Low-molecular weight gelators (LMWGs) are small molecules (M-w < similar to 1 kDa), which form self-assembled fibrillar network (SAFiN) hydrogels in water. A great majority of SAFiN gels are described by an entangled network of self-assembled fibers, in analogy to a polymer in a good solvent. Here, fibrillation of a biobased glycolipid bolaamphiphile is triggered by Ca2+ or Ag+ ions which are added to its diluted micellar phase. The resulting SAFiN, which forms a hydrogel above 0.5 wt%, has a nano-fishnet structure, characterized by a fibrous network of both entangled fibers and beta-sheet-like rafts, generally observed for silk fibroin, actin hydrogels or mineral imogolite nanotubes, but generally not known for SAFiN. This work focuses on the strength of the SAFIN gels, their fast recovery after applying a mechanical stimulus (strain) and their unusual resistance to temperature, studied by coupling rheology to small angle X-ray scattering (rheo-SAXS) using synchrotron radiation. The Ca2+-based hydrogel maintains its properties up to 55 degrees C, while the Ag+-based gel shows a constant elastic modulus up to 70 degrees C, without the appearance of any gel-to-sol transition temperature. Furthermore, the glycolipid is obtained by fermentation from natural resources (glucose and rapeseed oil), thus showing that naturally engineered compounds can have unprecedented properties, when compared to the wide range of chemically derived amphiphiles.

Automated summary

Low-molecular weight gelators (LMWGs) are small molecules that form self-assembled fibrillar network (SAFiN) hydrogels in water. This study focuses on the strength, fast recovery, and temperature resistance of SAFiN gels, using rheology and small angle X-ray scattering (rheo-SAXS) with synchrotron radiation. The Ca2+-based hydrogel maintains its properties up to 55 degrees C, while the Ag+-based gel shows constant elastic modulus up to 70 degrees C without any gel-to-sol transition temperature.