Protein scaffolds play a vital role in drug delivery
systems. However,
few research studies have been focused on loading hydrophobic drugs
on protein scaffolds in biomedical fields. Here, we report on the
development of protein microspheres and nanofibers by a simple ice-templating
approach and their use as scaffolds for the controlled release of
hydrophobic drugs, with bovine serum albumin (BSA) as the model protein
and curcumin as the model hydrophobic drug. The BSA scaffolds display
the unique nanofibrous and microspherical structures. This is a surprising
discovery because there has been no report on the formation of microspheres
via simple ice-templating of solutions or suspensions. To further
understand the formation of microspheres by this approach, lysozyme,
papain, and their composites with BSA are also studied. It is speculated
that nanoparticles are first formed in aqueous BSA solution, attributed
to the overlapping of hydration layers and autoassembly of inner hydrophobic
cores of BSA globular molecules. Nanoprecipitation and soaking evaporation
approaches are then used to load curcumin into the BSA scaffolds,
followed by cross-linking with glutaraldehyde vapor to improve stability
in an aqueous medium. The controlled release of curcumin is demonstrated,
paving the way for various hydrophobic drugs loaded into this biodegradable
and nonimmunogenic protein scaffold for potential treatments of diverse
diseases.