Abstract: Disclosed are compositions and synthesis methods that pertain to biocompatible polymeric capsules capable of undergoing backbone degradation and cargo release upon exposure to biologically relevant concentrations of hydrogen peroxide (50-100 ?M of H2O2). In the invention, bio-responsive polyester bearing boronic ester triggers groups that degrade upon exposure to low concentrations of H2O2. The degradation is induced by transformation of a boronic ester to a phenol, which undergoes a quinone methide rearrangement to break down the polyester backbone.