Figure 4.

Phototoxicities were determined by a CCK-8 assay of MDA-MB-231, A549, BT-474, and NIH3T3 cells cultured in collagen gel-containing cell medium (a) with or (b) without hydroxyapatite particles. All cells were treated with free Ce6 (10 μg/mL) or each sample (equivalent Ce6 10 μg/mL) for 4 h and illuminated for 10 min at a light intensity of 5.2 mW/cm² using a 670 nm laser source (n = 7, as multiple experiments, ** p < 0.01 compared to free Ce6). A detailed description of each sample was given in the Figure 3 legend.