In Vitro Phototoxicity Assay: A PDT-based Method to Evaluate the Phototoxic Potential of a Photosensitizer in Lung Cancer Cells

- Photodynamic therapy or PDT is a type of light therapy utilizing photosensitizers-- molecules activated by lights of specific wavelengths. An excited photosensitizer converts molecular oxygen present in cells to reactive oxygen species that cause cell death. To begin the assay, prepare a desired nanoparticle-based drug delivery system carrying the appropriate concentration of the photosensitizer, alone or in combination with a test drug.

Add the preferred concentration of this nanoparticle suspension into a culture of lung cancer cells. Incubate the culture in the dark for an appropriate time to facilitate cellular uptake of nanoparticles. Replace the suspension with the desired culture medium. Subsequently, position a photodynamic therapy fiber laser above the culture at an optimal distance facilitating uniform illumination. Irradiate the cells at an appropriate wavelength for the desired time and incubate overnight.

Replace the media with a suitable cytotoxicity measuring solution. Use a microplate reader to measure cell viability and quantify cytotoxic effects of the experimental treatment. Irradiated cells containing the photosensitizer show decreased viability. In the follow