Macroporous dextran hydrogels for controlled growth factor capture and delivery using coiled-coil interactions.

Macroporous hydrogels possess a vast potential for various applications in the biomedical field. However, due to their large pore size allowing for unrestricted diffusion in the macropore network, macroporous hydrogels alone are not able to efficiently capture and release biomolecules in a controlled manner. There is thus a need for biofunctionalized, affinity-based gels that can efficiently load and release biomolecules in a sustained and controlled manner. For this purpose, we report here the use of a E/K coiled-coil affinity pair for the controlled capture and delivery of growth factors from highly interconnected, macroporous dextran hydrogels. By conjugating the Kcoil peptide to the dextran backbone, we achieved controlled loading and release of Ecoil-tagged Epidermal and Vascular Endothelial Growth Factors. To finely tune the behavior of the gels, we propose four control parameters: (i) macropore size, (ii) Kcoil grafting density, (iii) Ecoil valency and (iv) E/K affinity. We demonstrate that Kcoil grafting can produce a 20-fold increase in passive growth factor capture by macroporous dextran gels. Furthermore, we demonstrate that our gels can release as little as 20% of the loaded growth factors over one week, while retaining bioactivity. Altogether, we propose a versatile, highly tunable platform for the controlled delivery of growth factors in biomedical applications. STATEMENT OF SIGNIFICANCE: This work presents a highly tunable platform for growth factor capture and sustained delivery using affinity peptides in macroporous, fully interconnected dextran hydrogels. It addresses several ongoing challenges by presenting: (i) a versatile platform for the delivery of a wide range of stable, bioactive molecules, (ii) a passive, affinity-based loading of growth factors in the platform, paving the way for in situ (re)loading of the device and (iii) four different control parameters to finely tune growth factor capture and release. Altogether, our macroporous dextran hydrogels have a vast potential for applications in controlled delivery, tissue engineering and regenerative medicine.