UV Light–Responsive Peptide-Based Supramolecular Hydrogel for Controlled Drug Delivery

Low-molecular-weight self-assembled peptides may serve as promising hydrogelators for drug delivery applications by changing their structural network in response to external stimuli. Herein, inspired by the well-studied low-molecular-weight peptide hydrogelator, fluorenyl-methoxycarbonyl-diphenylalanine (Fmoc-FF), a novel peptide is designed and synthesized to include an ultraviolet (UV)-sensitive phototrigger. Similar to Fmoc-FF, 6-nitroveratryloxycarbonyl-diphenylalanine (Nvoc-FF) self-assembles to form a 3D, self-supporting, nanofibrous hydrogel. The Nvoc-FF hydrogel exhibits good mechanical properties with a storage modulus of 40 kPa. UV irradiation of the Nvoc-FF hydrogel encapsulating insulin-fluorescein isothiocyanate (insulin-FITC) results in the cleavage of Nvoc-FF peptide to produce unmasked FF, thereby facilitating the degradation of the hydrogel and the release of insulin-FITC. This release is in linear correlation to the irradiation time. In the present study, a first insight into this rigid, fibrous, light-responsive hydrogel is provided, allowing the fabrication of a novel drug delivery system for controlled release of large molecules.