Figure 1.

Mesoporous-silica-coated UCNPs as an agent of PDT.

Notes: (A) Schematic of mesoporous-silica-coated UCNPs co-loaded with chlorin e6 (Ce6) photosensitizer for PDT. Following excitation at 980 nm, the UCNPs upconverted NIR light to VIS light of specific wavelengths to excite Ce6, and the activated photosensitizer subsequently generated cytotoxic ¹O₂ for biomolecule modification. (B) Comparison of ¹O₂ production as determined by the decay of ABDA fluorescence. ABDA fluorescence decay (measured at a peak intensity of 431 nm) was plotted as a function of exposure time (min) to an NIR laser (the experiments for each group were run in triplicate). (C) A comparison of penetration depth as determined via cell viability following PDT using different thicknesses of pigskin. (D) The intracellular accumulation of UCNPs-Ce6 as detected via laser confocal microscopy (Ce6 red fluorescence). **P<0.01, ***P<0.001 vs control group. Scale bar =0.1 mm.

Abbreviations: ABDA, 9, 10-anthracenediylbis (methylene) dimalonic acid; UCNPs, upconversion nanoparticles; PDT, photodynamic therapy; NIR, near-infrared; VIS, visible; ¹O₂, singlet oxygen; ³O₂, triplet oxygen; h, hours.