Design and synthesis of triphenylphosphonium-porphyrin@xylan nanoparticles for anticancer photodynamic therapy

Most photosensitizers (PS) suffer from a lack of water solubility and from a low selectivity toward tumor cells. Delivery systems using nanoparticles make it possible to improve PS water solubility, and also tumor targeting via the enhanced permeability and retention (EPR) effect. Among the organelles, mitochondria are attractive target sites for drug-delivery strategies since they perform a variety of key cellular processes. Our study was aimed at synthesizing nanoparticles consisting of xylan-carrying porphyrins attached to a triphenylphosphonium moiety, in order to enhance the PDT effect through mitochondrial targeting. Hybrid nanoparticles were designed that consisted of a silica core coated with xylan substituted with porphyrin derivatives carrying a triphenylphosphonium moiety. These hybrid nanoparticles have been constructed, along with their counterparts devoid of silica core, taking into consideration the controversy surrounding the use of silica nanoparticles. Phototoxicity experiments, conducted against the HCT-116 and HT-29 colorectal cancer cell lines, showed that nanoparticles with porphyrins bearing a triphenylphosphonium moiety exhibited an enhanced photocytotoxic effect in comparison with free porphyrin or nanoparticles with porphyrins without the triphenylphosphonium moiety.