Fibrin Hydrogels Reinforced by Reactive Microgels for Stimulus‐Triggered Drug Administration

Abstract Tissue engineering is a steadily growing field of research due to its wide‐ranging applicability in the field of regenerative medicine. Application‐dependent mechanical properties of a scaffold material as well as its biocompatibility and tailored functionality represent particular challenges. Here the properties of fibrin‐based hydrogels reinforced by functional cytocompatible poly( N ‐vinylcaprolactam)‐based (PVCL) microgels are studied and evaluated. The employment of temperature‐responsive microgels decorated by epoxy groups for covalent binding to the fibrin is studied as a function of cross‐linking degree within the microgels, microgel concentration, as well as temperature. Rheology reveals a strong correlation between the mechanical properties of the reinforced fibrin‐based hydrogels and the microgel rigidity and concentration. The incorporated microgels serve as cross‐links, which enable temperature‐responsive behavior of the hydrogels, and slow down the hydrogel degradation. Microgels can be additionally used as carriers for active drugs, as demonstrated for dexamethasone. The microgels’ temperature‐responsiveness allows for triggered release of payload, which is monitored using a bioassay. The cytocompatibility of the microgel‐reinforced fibrin‐based hydrogels is demonstrated by LIVE/DEAD staining experiments using human mesenchymal stem cells. The microgel‐reinforced hydrogels are a promising material for tissue engineering, owing to their superior mechanical performance and stability, possibility of drug release, and retained biocompatibility.