Mesoporous organosilica nanoparticles (PHT-PMO) have been prepared from an octa-triethoxysilylated Zn phthalocyanine precursor and showed powerful NIR photodynamic efficiency and siRNA photochemical internalization.

Photosensitizing nanogels were obtained through a surfactant-free single-step protocol by using a porphyrin-based cross-linker for stabilizing self-assembled nanosized aggregates of thermoresponsive copolymers. Nanogels with varying amounts of porphyrin retained the singlet oxygen generation ability of the porphyrin core and were also capable of inducing temperature increase upon irradiation at 635 nm. Photoinduced killing efficiency was tested against three cell lines: human breast adenocarcinoma (MDA-MB-231 and MCF7) and pancreatic adenocarcinoma (AsPC-1) cells, and a predominant photodynamic mechanism at 450 nm and a mixed photodynamic and photothermal effect at 635 nm was observed. This innovative access to photosensitizing nanogels is a proof of concept, and opens new perspectives toward the preparation of optimized nanophotosensitizers.

In line with current efforts to direct PDT photosensitizers to specific organelles such as mitochondria, a triphenylphosphonium-tetrasubstituted Zn phthalocyanine was designed, taking into account synthetic constraints. Triphenylphosphonium moieties were successfully introduced on alkyl bromide substituents on a pre-formed phthalocyanine. Photophysical and photochemical measurements showed that the photoproperties of the Zn phthalocyanine core were not affected by the triphenylphosphonium groups. Biological investigations demonstrated the dark innocuousness of the phthalocyanine up to 1 [Formula: see text]M, a concentration that exhibited a powerful phototoxicity. Cell death was confirmed to be photodynamically induced thanks to reactive oxygen species detection experiments. Nonetheless, the triphenylphosphonium moieties did not promote the accumulation of the phthalocyanine in mitochondria as significantly as expected.

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Abstract:Phthalonitriles are key precursors of phthalocyanines. Self-quenching dimeric phthalocyanines likely to be cleaved into monomeric species are of potential interest for tumour-site activated photosensitisers. Disulfide linkers can be specifically cleaved in tumoral tissue do to their reductive nature. Hence, a disulfide-linked phthalonitrile was designed to serve as further precursor of specifically tumour-activatable phthalocyanine-based photosensitising systems. Bisphthalonitrile with a disulfide-based linker and its dimethylene analogue were comparatively analyzed on a spectroscopic point of view as well as with DFT calculations. A thorough crystallographic analysis of the disulfide-linked derivative was conducted.