Bifunctional nanoparticle assemblies: photoluminescent and nitric oxide photodelivering monolayer protected platinum clusters

In this contribution the design and fabrication of bifunctional, photoresponsive hybrid metal nanoparticle assemblies is reported. Integration of tailored porphyrin and NO photodonor units into ca. 1 nm carboxy-terminated platinum induces the formation of particle nanoassemblies of ca. 10 nm, which are quite soluble in aqueous solution at physiological pH and exhibit a bichromophoric behavior. Direct monitoring of NO through an ultrasensitive NO electrode demonstrates that the nanoparticles are stable in the dark but supply NO at nanomolar level in a way exclusively regulated by light excitation. Besides, the typical red fluorescence arising from the porphyrin centers in the nanoassembly is not quenched extensively, offering a useful tool for mapping the localization of the nanoparticles in bio-environments. Overall these nanohybrids represent appealing bright point sources of NO to be tested in biological research in the perspective of practical application in the emerging field of nanomedicine.