Cytocompatible SiC/SiOx nanowires for X-ray-excited photodynamic therapy

The development of innovative nanosystems paves the way to multidisciplinary applications at the frontier between materials science and nanomedicine. In this work we present a novel hybrid nanosystem based on cytocompatible inorganic SiC/SiOx core/shell nanowires conjugated via click-chemistry procedures with an organic photosensitizer belonging to the class of porphyrins. We show that the bare nanowires do not elicit either midterm (72 h) or long-term (10 days) cytotoxic activity leading to irreversible cellular damages or death. The hybrid nanosystem upon irradiation with 6 MV X-Rays at low doses (0.4-2 Gy) is able to generate singlet oxygen, acting therefore as an effective agent for X-Ray-excited photodynamic therapy exploitable to treat deep-seated tumors. In-vitro tests on lung adenocarcinoma cells show that the nanosystem enhances the effects of radiation therapy. As evaluated by clonogenic survival assay 12 days after irradiation at a dose of 2 Gy, the cell population is reduced with respect to control cells by about 75%.