Light-activatable prodrugs based on hyaluronic acid biomaterials

Photosensitive in situ cross-linked hyaluronan (HA) hydrogels are prepared by modular chemoselective assembly from the biopolymer precursors and novel heterobifunctional linkers with middle photo-labile ortho-nitrobenzyl group and orthogonally reactive terminals. Starting from the thiol-modified HA and a linker with activated disulfide and hydrazide terminals, a photo-degradable HA hydrogel was prepared by the hydrazone cross-linking reaction. Moreover, a light-triggered drug-releasing hydrogel prodrug was constructed by an orthogonal conjugation of dopamine (DA) via a photo-labile linker to HA dually modified with thiol and hydrazide groups (hy-HA-SH) and a subsequent cross-linking with aldehyde-derivatized HA (HA-al). On-demand release of DA from the hydrogel was achieved upon exposure of the hydrogel to UV light whereas 11-fold less release of the drug was observed in the absence of light. The mechanical properties of the hydrogels, photodegradation kinetics, photorelease of the model drugs were studied by rheology, spectrophotometry, chromatography, and mass spectrometry. For the first time, integration of photolabile components into an actual polysaccharide of extracellular matrix was implemented for the light-controlled release of drug molecules.