2-Hydroxy-5-nitrobenzyl as a Diazeniumdiolate Protecting Group: Application in NO-Releasing Polymers with Enhanced Biocompatibility

The 2-hydroxy-5-nitrobenzyl group is shown to be an effective protecting group for diazeniumdiolates. O(2)-(2-hydroxy-5-nitrobenzyl)-substituted diazeniumdiolates display enhanced thermal stability, but efficiently release nitric oxide (NO) in pH 7.4 aqueous solutions. A lipophilic analogue incorporated into hydrophobic polymers shows NO surface flux rates comparable to that of the natural endothelium. Importantly, these polymer formulations also show significantly enhanced biocompatibility in vivo with use of a porcine implant model.