Biodegradable polyoxalate and copolyoxalate particles for drug-delivery applications

Polyoxalate and copolyoxalate were developed in the 1970s and have been used for biomedical applications such as suture coating purposes, owing to their biocompatibility and biodegradability. They are known to degrade into diols and oxalic acid, which are considered biocompatible. One of the advantages of oxalate-based polymer is the ease of control of physicochemical properties, such as biodegradability, crystallinity and mechanical strength. The composition and hydrophobicity of diols greatly influenced their hydrolytic stability and mechanical properties. Oxalate-based polymers have faster hydrolytic-degradation kinetics than the commercial biodegradable polymers, poly(lactide-co-glycolide) and poly(caprolactone). Recently, our group has developed fully biodegradable polymer drug carriers based on oxalate-based polymers that are composed of various diols. The hydrophobicity of the oxalate-based polymers allowed them to be formulated into nano- or micro-particles, which are suitable for targeting macrophages in inflammatory diseases. The nano- or micro-particles exhibited excellent cytotoxicity profiles and fast drug-release kinetics, suggesting great potential as drug-delivery systems for the treatment of acute inflammatory diseases. In this article, we discuss the synthesis and physicochemical properties of oxalate-based polymers which can be used as a drug-delivery vehicle for the treatment of inflammatory diseases.