Dose Limited Fluorescence Microscopy of Living Cells

Light dose plays an important role for maintaining viability in optical microscopy of living cells. Therefore, a colony forming assay was established, and non-phototoxic light doses were determined for glioblastoma cells. These doses ranged from a few 1 J/cm 2 or even less for cells incubated with fluorescence markers or photosensitizers up to about 100 J/cm 2 for non-incubated cells. Microscopic methods were adapted to those light doses, and often wide field methods appeared to be more appropriate than laser scanning methods.