Different energy inputs promotes helicity change in the supramolecular arrangement of carbohydrates

Glycans participate in a vast number of biomolecular recognition events. Their specificity in these events is related with the high number of carbohydrate regio- and/or stereoisomers. We explore this rich (bio)chemical diversity to develop a small library of carbohydrate amphiphiles (i.e. Fmoc derivatives) able to assemble into nanofibers that further form gels under physiological conditions. Herein, we investigated the effect of the energy input (heating/cooling rate) and the carbohydrate stereochemistry on the assembled architectures (nanofibers and gels) and their mechanical properties. We selected glucosamine (Glc), galactosamine (Gal) and mannosamine (Man) N-functionalized with Fmoc, and studied their ability to gel by a heating and cooling cycle. While Fmoc-Glc and Fmoc-Gal assembled into nanofibers (AFM and SEM) and formed gels, the Fmoc-Man amphiphile was poorly soluble in aqueous media. The cooling rate affected the structure of the nanofibers formed by Fmoc-Gal: we observed opposite helicity (CD) for fast (40 ºC/min) and slow cooling rate (5 ºC/min). This altered helicity influences the macroscopic properties of the ensuing gels (G’_{slow cooling}>G’_{fast cooling}) such as gelling temperature (Tgel_{slow cooling}>Tgel_{fast cooling}); mechanical properties and stability. In conclusion, we demonstrated that biosystems can use carbohydrate isomers to generate diverse 3D systems as a function of the available energy input.