Novel hydrogels for wound care applications

Abstract

Hydrogels are cross-linked, three-dimensional hydrophilic polymeric networks. They possess similarity in structure to the soft tissue in the body, thus have found a great number of applications as biomaterials. For wound care applications, hydrogels are considered to be new forms of wound dressings. Hydrogels with designed properties can act as a barrier for wounds while fastening the healing process. They can also cargo macromolecules encapsulated within their structure that are necessary for wound regeneration and protection. The aim of this thesis is to synthesize redox responsive hydrogels that can be applied as wound care materials. Said hydrogels were designed to obtain a tissue regeneration triggering, non-cytotoxic and on-demand degradable hydrogel dressing to avoid disturbance of tissue while the material is physically removed. To do so, hyaluronic acid, a natural polymer constituent of human soft tissue, was modified with furan groups to construct hydrogels through reaction with a maleimide and disulfide functional group containing redox-responsive PEG-based crosslinker by Diels-Alder cycloaddition. The stimuli responsive degradation features are tuned by varying the amount of crosslinker in hydrogels. The change of porosity and disulfide concentration was expected to effect the degradation rates. It was demonstrated that hydrogels with higher crosslinking density exhibited greater strength, along with longer degradation times. All hydrogels exhibited high swelling capacity. To examine the passive and on-demand delivery of tissue regenerative macromolecules from this system, a model protein, namely, FITC-BSA was encapsulated within the hydrogels. The release of these biomolecules were investigated in PBS (pH=7.4), in absence and presence of the reducing agent DTT, to observe the passive and on-demand release profiles. Importantly, complete dissolution of the hydrogel was accomplished under mild conditions upon exposure to a solution containing the reducing agent.