Recent advance in polymer based microspheric systems for controlled protein and peptide delivery

: Sustained-release systems made by biodegradable polymers for protein and peptide drug delivery have received considerable attention by academic researchers and major pharmaceutical companies around the world. Various types of biodegradable materials, including natural and synthetic polymers, have been applied to form protein and peptide drug carriers. Among these material candidates, poly lactic acid (PLA) and poly lactic-co-glycolic acid (PLGA) are the most commonly used biodegradable materials in the development of protein and peptide microspheres. In addition, many microsphere preparation technologies, including spray drying, coacervation, multiple emulsion solvent evaporation method and microporous membrane emulsification have been developed for microspheres preparation. In this review, we particularly summarize and briefly introduce the materials and methods that are used to fabricate microspheres as protein delivery systems. The existing opportunities and challenges for successful protein delivery are also discussed.