Redox-responsive hydrogels of thiolated pectin

Hydrogels are one the utmost polymeric materials employed in drug delivery, especially those constituted with polysaccharides due to their biocompatibility, non-toxicity, and renewability. These hydrogels are either prepared by physical or chemical crosslinking of the polysaccharide chains, where the latter have gained special attention since the crosslinking process is easily controlled. To improve the efficiency of this type of hydrogel towards drug release, the chemical crosslinks should have a responsive nature, allowing their breaking in the presence of a trigger, such as pH or temperature. A scarcely explored type of chemical crosslink is those with a redox-responsive nature, which is intriguing since many redox molecules are present in different wounds (from burn to scratch wounds). Generally speaking, in the presence of physiological redox agents, the redox-responsive chemical crosslinks are broken, which may facilitate the controlled and local release of drugs from the hydrogel. Within this framework, we have developed a redox-responsive hydrogel of thiolated pectin crosslinked by disulfide bonds, which are broken in the presence of physiological redox molecules, such as cysteine or glutathione. The crosslinking of the thiolated pectin chains was induced by the addition of potassium persulfate (KPS), which reacts with the thiol groups, and promotes the formation of the disulfide bonds. Through several characterization analyses (FTIR, rheology, swelling, weight loss, and drug release experiments,), we have demonstrated the photo-responsive properties of the synthesized hydrogels.