Surface and bulk modifications to photocrosslinked polyanhydrides to control degradation behavior

A unique class of surface-eroding polyanhydrides was developed and explored for use in medical applications requiring high-strength biomaterials (e.g. , orthopedics). In particular, dimethacrylated anhydride monomers were synt hesized that photopolymerize quickly to render densely crosslinked polymer networks that degrade from the surface only by hydrolysis of labile anhydri de Linkages. Previous research on these materials has shown that the rate o f hydrolysis of the degradable Linkages is dependent on the hydrophobicity of the network composition. This article demonstrates the versatility in co ntrolling the degradation process and resulting cellular response in these materials through the incorporation of new chemistries and the formation of polymer-polymer composite structures. Specifically, the rate of mass loss was controlled by the addition of hydrophobic linear polymers [e.g., poly(m ethyl methacrylate)] or monovinyl monomers based on hydrophobic natural com ponents (e.g., cholesterol, steric acid). In addition, a newly established photografting method was used to modify the network surface chemistry with cholesterol- and stearic acid-based polymer grafts to control the degradati on front and cellular interactions at the polymer-tissue interface. Finally , a porogen leaching method was used to form porous polyanhydride construct s, which can be subsequently filled with osteoblasts photoencapsulated in a hydrogel, as potential synthetic allograft materials for tissue engineerin g bone. (C) 2000 John Wiley & Sons, Inc.