Fig. 3.

In vitro photon conversion and cellular cytotoxicity of UCMS@Pep. A UV-vis spectrum of UCMS@Pep-RB (red line) and up-conversion emission spectrum of UCMS@Pep under excitation at 980 nm (green color). B Effects of irradiation time on the fluorescence intensity change of SOSG at 525 nm for different samples. C Relative viability of LLC cells incubated with different concentrations of blank nanoparticles, UCMS@Pep alone, and UCMS@Pep with NIR laser. D Results of calcein-AM & PI staining that was used to discriminate between live and dead cells (a: Control, b: NIR laser, c: UCMS@Pep, d: UCMS@Pep-RB + NIR laser, scale bar = 100 μm). (E Flow cytogram showing the results of the apoptosis assay based on the annexin V-FITC and propidium iodide (PI) staining of LLC cells after different treatments. F Corresponding inverted fluorescence microscopy images of DCFH-DA probe–stained LLC cells used to evaluate the overall intracellular ROS generation (scale bar = 50 μm). (*P < 0.05, **P < 0.01, ***P < 0.001, n = 3)