COMBINATION OF ATOMIC FORCE MICROSCOPY AND COMET ASSAY FOR ANALYSIS OF DNA DAMAGE INDUCED BY PDT

The aim of the present study was to evaluate the efficiency of photosensitisation induced by two photosensitizers, TMPyP and ClAlPcS2, tested in vitro on the tumor cell line MCF7. The oxidative damage of DNA in MCF-7 cells was analyzed by comet assay (CA) combined with Atomic Force Microscopy (AFM). The ability of detection of apoptotic response detected by Atomic Force Microscopy at the individual molecule level of DNA was successfully demonstrated; when DNA get damaged, cleavage to fragments caused by photodynamic treatment was directly visualized by AFM imaging of individual molecules. Its accuracy and reliability was validated through the comparison with traditional single cell agarose electrophoresis