Photo-toxic effects of 809-nm diode laser and indocyanine green on MDA-MB231 breast cancer cells.

Photodynamic therapy (PDT), due to its positive outcomes in clinical applications, easiness of practice and few side effects, is a good candidate for an efficient treatment of cancer. Indocyanine green (ICG), a water-soluble, anionic tricarbocyanine and non-toxic molecule is a promising photosensitive agent for PDT applications on tumor cells. ICG exhibits strong maximum absorption at around 805 nm which will be an advantage for its use in PDT; light at that wavelength can be used to treat deeper tumors. In this study the inhibitory growth effects of ICG-PDT on MDA-MB231 human breast cancer cells were investigated in a time course experiment. Cells were irradiated with a continuous wave diode laser (lambda=809 nm, 60 mW, 24 J cm(-2)). Cell viability was measured by MTT assay 0, 3, 6, 9, 12, 24 and 48h after light irradiation. The results showed that ICG-PDT application exerted its photo-oxidative effect on MDA-MB231 breast cancer cells immediately. Relative cell viability was determined throughout the 48h time course, and a consistent decrease was observed after ICG-PDT applications. In conclusion, ICG when used in combination with near-infrared light showed a very fast (within 3h) and persistent (up to 48h) photo-toxic effect on MDA-MB231 human breast cancer cells.