Determination of Infrared Laser Energy Dose for Cancer Cells Inactivation as a Candidate of Photodynamic Therapy

The aim of this research is to find out the effect of GaAlAs diode laser 808 nm exposure on MCF-7 breast cancer cells in vitro with and without the addition of a photosensitizer. Methylene blue (C₁₆H₁₈N₃SCl) with concentration of 2 μM is used as the photosensitizer based on the preliminary results of cytotoxicity assay. Energy dose is set in the range of 23, 043 to 322, 062 J/cm². Laser exposure with the addition of the photosensitizer generates the highest percentage of cell death of 20.80% at energy dose of 184, 344 J/cm² and cell death begin to decrease at energy dose above this value. This behavior is likely caused by photodegradation and photobleaching effect of the photosensitizer due to the longer exposure time. However, the percentage of cell death without the addition of photosensitizer is increased proportionally to the increase of energy dose and achieved 32, 45% cell mortality at 299, 559 J/cm². This study not only shows that the exposure of infrared laser can be used to inactivate cancer cells but also determines its optimum energy dose, makes it a possible candidate for photodynamic therapy in the future.