Figure 5. Photo- and cytotoxicity of 1D9-700DX against HeLa cells.
(A–D) HeLa cells were incubated with 1D9-700DX or IRDye700DX carboxylate (IRDye700DX-C) for 30 minutes, and the unbound conjugate was (A and C) or was not (B and D) removed by washing with PBS prior treatment with red light (+) at a radiant exposure of 30 J.cm–2. (A and B) Photo- and cytotoxicity was assessed using the colorimetric MTT assay 24 hours after treatment. The percentage of cell viability was calculated relative to viable control cells that were mock-treated with PBS in the dark. Cells treated with 1% were used as a negative control for cell killing. (C and D) Quantification of H2DCFDA fluorescence intensity (y axis) by fluorescence spectroscopy immediately after treatment as a measure for ROS production. Data are presented as mean ± SEM of 3 independent experiments performed in triplicates (A and B) and duplicates (C and D). Kruskal-Wallis tests with subsequent Dunn′s multiple-comparison tests were used for statistical analysis. Significant differences compared with the control group (no photosensitizer and no light) are marked as follows: ****P < 0.0001.