Fibrin-dextran hydrogels with tunable porosity and mechanical properties

Abstract text (incl. figure legends and references)

The increased use of hydrogels in scaffolds for cells, bioprinting materials, or drug delivery carriers has increased the demand for novel macromolecular building blocks to tune their structure and properties. Conventional natural hydrogels based on collagen or fibrin are limited by their weak mechanical properties and fast degradation rate, while hydrogels based on synthetic polymers face issues with biocompatibility and biodegradation. Therefore, the combination of natural and synthetic polymers is an interesting approach to design hydrogels with the best combination of properties for biomedical applications. A novel biobased hydrogel can be formed by using fibrin and the biopolymer dextran to control the mechanical properties. In this work, we synthesized fibrin and dextran with glycidyl methacrylate (dextran-MA)-based interpenetrating hydrogel networks with tailorable mechanical properties, controlled degradation, and variable pore sizes, which have the ability to support cell proliferation. Obtained hydrogels consist of two networks resulting from the in-situ gelation and crosslinking of fibrinogen and dextran-MA by adding thrombin and dithiothreitol. By varying the amounts and ratio of the precursor"s fibrinogen, dextran-MA and crosslinker dithiolthreitol, hydrogels with high mechanical stability, retarded degradation rates and controlled fibre orientation could be achieved. Swelling experiments and NMR diffusometry measurements showed that the water uptake and mesh sizes of fabricated hydrogels decrease with the increase of dextran-MA concentrations. Imaging methods, such as 2-photon microscopy and cryo-SEM, were utilized to visualise fibrin-dextran hydrogels and determine the fibre thickness. The mesh sizes were determined based on these results and using 1H-NMR diffusometry. Cell viability tests with L929 mouse fibroblasts and human mesenchymal stem cells (MSC) were performed.