Fully photodegradable block copolymer nanoparticles for dual release of cargo and radicals

•Fully photodegradable block copolymer nanoparticles containing o-nitrobenzyl group.•Self-immolation mechanism is triggered by a dual photoinduced H-atom abstraction.•Chain scission and o-nitrobenzyl group cleavage take place simultaneously.•The nanoparticles can release a guest molecule in response to irradiation.•The burst release of radicals accompanying degradation can destroy target molecules.