PEG-Thiol based hydrogels with controllable properties

Poly(ethylene glycol)-Thiol (PEG-Thiol) hydrogels are a prime example for biocompatible hydrogels that are used in biomedical applications, such as drug delivery and regenerative medicine. Different cross-linking chemistries exist in order to create hydrogel networks of PEG-Thiol hydrogels, with Michael-type addition reactions and acrylate polymerization being the most popular ones. Here we tested hydrogels composed of PEGDA and 4-arm PEG-Thiol (PEG-4SH) with equimolar ratios between acrylates and thiols. The polymer solutions of PEG-4SH were mixed for different time intervals prior to their mixing with PEGDA solutions. Swelling experiments, rheology testing and Young’s modulus measurements were performed in order to study structure and properties of the resultant hydrogels. The manipulation of architecture and properties was achieved by alterations in the preparation procedure. Consequently, this methodology, which gives further insights into the impact of the polymerization mechanism on PEG-Thiol based hydrogel properties, can be readily applied to develop hydrogel biomaterials that are tailor-made for specific biomedical applications.