Generating Pores within Protein-Based Biomaterials without Compromising Their Structural Integrity

Marina Slawinski, “Generating Pores within Protein-Based Biomaterials without Compromising Their Structural Integrity”
Mentor: Ionel Popa, Physics
Oral Presentation Block 1

Increasing the porosity of biomaterials is desirable for designing 3-D cell culture scaffolds with physical and mechanical properties similar to the native extracellular matrix (ECM) and creating permeable biomaterials capable of transferring large molecules. However, producing a highly porous substrate without compromising its mechanical properties has posed challenges, as formation of pores typically comes at the expense of the primary network. Here, we synthesize dual-network protein-polysaccharide hydrogels with increased permeability without diminishing the material’s mechanical stability. A photoactivated reaction is used to covalently cross-link bovine serum albumin (BSA) protein molecules, while the inclusion of a polysaccharide – alginate – during synthesis allows for the formation of a secondary network obtained through its ionic interaction with calcium cations. Alginate chains associate with calcium cations to form an insoluble gel during the growth of the covalent protein network, reshaping its backbone structure. When subsequently exposed to solution lacking calcium, the alginate chains revert to their water-soluble form, leaving vacancies in the protein network. SEM and confocal laser scanning microscopy images revealed an increase in porosity compared to pure-protein BSA hydrogels. Characterization of mechanical response through force-clamp rheometry demonstrated that the Young’s Modulus of the porous-BSA hydrogels is comparable to that of pure-BSA hydrogels, while filtration experiments confirmed that the increased porosity allows for better percolation of various solutes. The methods used here allow for the synthesis of highly porous hydrogels without sacrificing the mechanical properties compared to nonporous counterparts. The increased permeability offers new possibilities in the design of biomaterial cell scaffolds and filters.