Biomedical polymers surface erodibility

The past two decades have produced a revival of interest in the synthesis of polyanhydrides for biomedical applications. These materials offer a unique combination of properties that includes hydrolytically labile backbone, hydrophobic bulk, and very flexible chemistry that can be combined with other functional groups to develop polymers with novel physical and chemical properties. This combination of properties leads to erosion kinetics that is primarily surface eroding and offers the potential to stabilize macromolecular drugs and extend release profiles from days to years. The microstructural characteristics and inhomogeneities of multi-component systems offer an additional dimension of drug release kinetics that can be exploited to tailor drug release profiles. 

Polyanhydrides form a class of surface-eroding polymers that have been extensively studied solely for biomedical applications. Although the first synthesis of polyanhydrides was reported as early as 1909, the low hydrolytic stability of aliphatic anhydrides coupled with the low molecular weight of many of these polymers barred them from any industrial application until 1980, when they were suggested as ideal candidates for drug-delivery applications. Various polymerization techniques have been developed for the synthesis of very-high-molecular-weight polymers. 

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