Figure 4.

Deep tissue penetration of UCNPs‐based phototherapy in vitro. a) Detection of ROS in PM‐PAAO‐UCNP‐incubated foam cells using DCFH‐DA staining with 660 or 980 nm laser irradiation. One centimeter thick tissues were put on a cell‐culture dish to mimic in vivo condition (scale bar, 50 µm). Schematic illustration on the right shows the experimental procedure. b) Cell apoptosis detected using an Annexin V‐FITC/PI apoptosis detection kit after PDT treatment. c) The effect of PDT on lipid storage in foam cells measured with Oil Red O staining (scale bar, 50 µm). d) The ratio of Oil Red O stained cells in total 1 × 10⁶ cells. The results are presented as mean ± SD (n = 3). Statistical significance was evaluated using one‐way ANOVA. *p < 0.05, **p < 0.01, ***p < 0.001.