Thiol-mediated coupling chemistry as a crosslinking method to prepare dynamic, self-healing hydrogels
Kimberly Brock (TNW-DBE), Romen Carrillo (IPNA-CSIC), Julieta I. Paez (TNW-DBE)
Abstract
Inspired by the natural environment of cells, the aim of this work is to develop hydrogels that can mimic the extra cellular matrix (ECM), with special attention to the dynamicity and stress relaxing characteristics. This research focusses on using dynamic covalent chemistry (DCC), consisting of a versatile toolbox of reactions of diverse bonds that are strong yet dynamic, to better mimic the natural dynamicity of the ECM. Additionally, the DCC hydrogels offer interesting properties such as self-healing behaviour and stress relaxation.
Here, a novel type of thiol-based dynamic covalent chemistry used as a crosslinking strategy to form tuneable, dynamic hydrogels for cell encapsulation is presented. The functional groups are attached to a polyethylene glycol (PEG) backbone. Hydrogels form rapidly in a few seconds to minutes by mixing the two precursors react under physiological conditions (aqueous buffer, room temperature). The mechanical properties of the resulting were characterized by shear rheology. Furthermore, the hydrogels have self-healing properties, due to the dynamic character of the bonds, and show recovery of the storage modulus after increased strain. Furthermore, the material shows moderate stress relaxation, an important parameter for the viscoelasticity of the material. Human mesenchymal stem cells (hMSCs) were encapsulated in the hydrogel and the acute toxicity was assessed by a live/dead assay after 2 hours of encapsulation.
This study showcases the applicability of this novel thiol-mediated dynamic covalent chemistry to make tuneable, self-healing, stress-relaxing hydrogels, that show potential for biomedical applications.