No abstract

To create an ideal graft substitute for regenerating bone, the scaffold should possess osteoconductive, osteoinductive, and osteogenic properties. Hydrogels are a very common scaffold, but the mechanical integrity and nanoporous structure are not advantageous for bone regeneration. Cryogelation is a technique in which the controlled freezing and thawing of a polymer creates a spongy, macroporous structure with ideal structural characteristics and promising mechanical stability. Hydrogels and cryogels of three different materials (chitosan-gelatin, N-vinyl-2-pyrrolidone, and silk fibroin (SF)) were compared to assess the optimal material and form of scaffold for this application. Cryogel and hydrogel structures were tested in parallel to evaluate porosity, swelling, mechanical integrity, cellular infiltration, and mineralization potential. Cryogels proved superior to hydrogels based on swelling potential and mechanical properties. Among the cryogels, SF demonstrated high pore diameter and area, mineralization upon cellular infiltration, and the largest presence of osteocalcin, a marker of bone formation. These results demonstrate the practicality of cryogels for a bone regeneration application and identify SF as a potential material choice.

Honey is well-known for its wound healing capability and Manuka honey (MH) contains a unique Manuka factor, providing an additional antibacterial agent. Previously, there has not been a practical way to apply MH to a wound site, which renders treatment for an extended period extremely difficult. Tissue-engineered scaffolds offer an alternative treatment method to standard dressings by providing varying geometries to best treat the specific tissue. MH was incorporated into cryogels, hydrogels, and electrospun scaffolds to assess the effect of scaffold geometry on bacterial clearance and adhesion, as well as cellular adhesion. Electrospun scaffolds exhibited a faster release due to the nanoporous fibrous geometry which led to a larger partial bacterial clearance as compared to the more three-dimensional cryogels (CG) and hydrogels (HG). Similarly, the fast release of MH from the electrospun scaffolds resulted in reduced bacterial adhesion. Overall, the fast MH release of the electrospun scaffolds versus the extended release of the HG and CG scaffolds provides differences in cellular/bacterial adhesion and advantages for both short and long-term applications, respectively. This manuscript provides a comparison of the scaffold pore structures as well as bacterial and cellular properties, providing information regarding the relationship between varying scaffold geometry and MH efficacy.