Simultaneous supramolecular activation of NO photodonor/photosensitizer ensembles by a calix[4]arene nanoreactor

Micellar-like nanoassemblies of an amphiphilic calix[4]arene are able to co-encapsulate a hydrophobic nitric oxide (NO) photodonor (NOPD) together with either hydrophobic or hydrophilic porphyrinoid singlet oxygen (1O2) photosensitizers (PSs). The calix[4]arene-based host behaves as a suitable nanoreactor since it remarkably amplifies the NO photorelease effectiveness of the NOPD and switches on the capability of the PSs to photogenerate cytotoxic 1O2, otherwise precluded in water medium. The lack of reciprocal interferences, both in the ground and the excited states, of the individual guest components even if co-localized in the same nano-environment allows them to operate independently upon visible light excitation. This results in a double photodynamic action as demonstrated by the direct and real-time detection of NO and 1O2 through amperometric measurements and time-resolved infrared luminescence.