Material characterization of microsphere-based scaffolds with encapsulated raw materials.

"Raw materials," or materials capable of serving both as building blocks and as signals, which are often but not always natural materials, are taking center stage in biomaterials for contemporary regenerative medicine. In osteochondral tissue engineering, a field leveraging the underlying bone to facilitate cartilage regeneration, common raw materials include chondroitin sulfate (CS) for cartilage and β-tricalcium phosphate (TCP) for bone. Building on our previous work with gradient scaffolds based on microspheres, here we delved deeper into the characterization of individual components. In the current study, the release of CS and TCP from poly(D, L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds was evaluated over a time period of 4 weeks. Raw material encapsulated groups were compared to 'blank' groups and evaluated for surface topology, molecular weight, and mechanical performance as a function of time. The CS group may have led to increased surface porosity, and the addition of CS improved the mechanical performance of the scaffold. The finding that CS was completely released into the surrounding media by 4 weeks has a significant impact on future in vivo studies, given rapid bioavailability. The addition of TCP seemed to contribute to the rough external appearance of the scaffold. The current study provides an introduction to degradation patterns of homogenous raw material encapsulated scaffolds, providing characterization data to advance the field of microsphere-based scaffolds in tissue engineering.