FIGURE 4.

Biomacromolecule release kinetics can be controlled by the incorporation method and location within the substrate. (a) Growth factors and cytokines are encapsulated within polymeric microspheres and subsequently used to fabricate porous scaffolds. The protein is embedded more deeply within the biomaterial, and release is dependent upon polymer degradation and/or diffusion through the polymer layer and transport through the porous structure. (b) The covalent association of the protein with the biomaterial results in the macromolecule residing on or near the pores of the substrate and yields more rapid release