Fig. 5. (a) The ratios of PDT cell viability to dark cell viability under hypoxia. Cells were irradiated with white light (400–800 nm, 30 mW cm^–2, 10 min). Flow cytometric assay of cell death induced by (b) control cells, (c) Ru1 and (d) Ru2 (5 μM) mediated PDT under hypoxia.