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

Abstract

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.