NIR-responsive dextran / poly(lactide) hydrogels: Characterization of cleavable hydrogels and photoactivated release...

Polysaccharide-based hydrogels often lack mechanical strength and, when used for protein delivery, are generally limited to diffusion-based release. In this work, we developed robust polysaccharide- and polyester-based near-infrared (NIR)-responsive hydrogels. Hydrogels are made from photo-crosslinked methacrylated dextran (DEX-MA), methacrylated polylactide containing oxygen reactive species (ROS) sensitive thioketal groups (PLA-TK-MA), and covalently bound protoporphyrin IX (PPIX) that generates ROS under NIR irradiation. We investigated the effects of DEX methacrylation degree (3, 12 and 45 %), PLA molecular weight (2500 vs. 5000 g.mol^-1) and DEX/PLA ratios (95/5 to 50/50) on the gels' rheological properties. We then examined the NIR-sensitivity of selected hydrogels by comparing their water uptakes and storage/loss moduli. Finally, we studied the release of a model protein, bovine serum albumin (BSA), from the hydrogels with and without NIR-irradiation. Results confirmed that protein release kinetics can be controlled by NIR-irradiation, with faster and complete release of BSA compared to non-irradiated samples.