Understanding the self-assembly of Fmoc-phenylalanine to hydrogel formation.

Hydrogels of low molecular weight molecules are important in biomedical applications. Multiple factors are responsible for hydrogel formation, but their role in governing self-assembly to hydrogel formation is poorly understood. Herein, we report the hydrogel formation of fluorenylmethyloxycarbonyl phenylalanine (FmocF) molecule. We used physical and thermal stimuli for solubilizing FmocF above the critical concentration to induce gel formation. The key role of Fmoc, Fmoc and phenylalanine covalent linkage, flexibility of phe side chain, pH, and buffer ions in self-assembly of FmocF to gel formation is described. We found that the collective action of different non-covalent interactions play a role in making FmocF hydrogel. Using powder diffraction and infrared spectroscopy, we also report a new polymorphic form of FmocF after transitioning to hydrogel. In addition, we are proposing a model for drug release from FmocF hydrogel.