Porphyrin-based supramolecular nanofibres as a dynamic and activatable photosensitiser for photodynamic therapy.

Photodynamic therapy (PDT) represents a promising treatment modality for a range of cancers and other non-malignant diseases due to its non-invasive nature arising from the light-dependent activation. However, PDT has not been the first-line treatment of cancer thus far as a consequence of, among others, the lack of effective transport and activation strategies, and the undesired side effect caused by skin photosensitisation induced by the "always on" photosensitisers. To overcome this "Achilles' heel", we present herein a non-covalent approach to construct a one-component dynamic supramolecular nanophotosensitising system based on a carefully designed porphyrin. The control of the photoactivities of the resulting supramolecular fibres lies in the spatiotemporal control of the monomer-polymer equilibrium. Both the thermodynamics and kinetics of this nanosystem have been carefully studied by different techniques. Moreover, in vitro and in vivo studies have also been performed, showing that these supramolecular aggregates exhibit facile cell internalisation and progressive disassembly after being endocyted by targeted cells, leading to activation of the photosensitising units and eventually cell death and tumour eradication under photoirradiation.