Silent Death by Sound: C₆₀ Fullerene Sonodynamic Treatment of Cancer Cells

The acoustic pressure waves of ultrasound (US) not only penetrate biological tissues deeper than light, but they also generate light emission, termed sonoluminescence. This promoted the idea of its use as an alternative energy source for photosensitizer excitation. Pristine C₆₀ fullerene (C₆₀), an excellent photosensitizer, was explored in the frame of cancer sonodynamic therapy (SDT). For that purpose, we analyzed C₆₀ effects on human cervix carcinoma HeLa cells in combination with a low-intensity US treatment. The time-dependent accumulation of C₆₀ in HeLa cells reached its maximum at 24 h (800 ± 66 ng/10⁶ cells). Half of extranuclear C₆₀ is localized within mitochondria. The efficiency of the C₆₀ nanostructure's sonoexcitation with 1 MHz US was tested with cell-based assays. A significant proapoptotic sonotoxic effect of C₆₀ was found for HeLa cells. C₆₀'s ability to induce apoptosis of carcinoma cells after sonoexcitation with US provides a promising novel approach for cancer treatment.