SWCNT–porphyrin nano-hybrids selectively activated by ultrasound: an interesting model for sonodynamic applications

Sonodynamic therapy (SDT) is an innovative anticancer approach, based on the excitation of a given molecule (usually a porphyrin) by inertial acoustic cavitation that leads to cell death via the production of reactive oxygen species (ROS). This study aims to prepare and characterize nanosystems based on porphyrin grafted carbon nanotubes (SWCNTs), to understand some aspects of the mechanisms behind the SDT phenomenon. Three different porphyrins have been covalently linked to SWCNTs using either Diels–Alder or 1,3-dipolar cycloadditions. ROS production and cell viability have been evaluated upon ultrasound irradiation. Despite the low porphyrin content linked on the SWCNT, these systems have shown high ROS production and high tumour-cell-killing ability. The existence of a PET (photoinduced electron transfer)-like process would appear to be able to explain these observations. Moreover, the demonstrated ability to absorb light limits the impact of side effects due to light-excitation.