RESUMEN
LiYF4:Tm(3+)/Yb(3+) upconverting nanoparticles (UCNPs) were functionalized with the second generation photosensitizer 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (m-THPC, Temoporfin, Foscan®). m-THPC was modified using 4-(bromomethyl)benzoic acid, which induced a bathochromic shift of the m-THPC blue absorption peak. The nanoconstruct causes up to 70% cell death under 980 nm irradiation.
Asunto(s)
Mesoporfirinas/química , Nanopartículas/química , Fármacos Fotosensibilizantes/química , Oxígeno Singlete/química , Supervivencia Celular/efectos de los fármacos , Células HeLa , Humanos , Rayos Infrarrojos , Fármacos Fotosensibilizantes/síntesis química , Fármacos Fotosensibilizantes/toxicidad , Oxígeno Singlete/metabolismoRESUMEN
We report on the first experimental observation of stable optical trapping of dielectric NaYF4:Er(3+),Yb(3+) upconverting fluorescent nanoparticles (~26 nm in diameter) using a continuous wave 980 nm single-beam laser. The laser serves both to optically trap and to excite visible luminescence from the nanoparticles. Sequential loading of individual nanoparticles into the trap is observed from the analysis of the emitted luminescence. We demonstrate that the trapping strength and the number of individual nanoparticles trapped are dictated by both the laser power and nanoparticle density. The possible contribution of thermal effects has been investigated by performing trapping experiment in both heavy water and into distilled water. For the case of heavy water, thermal gradients are negligible and optical forces dominate the trap loading behaviour. The results provide a promising path towards real three dimensional manipulation of single NaYF4:Er(3+),Yb(3+) nanoparticles for precise fluorescence sensing in biophotonics experiments.
RESUMEN
The luminescence properties of a Pr3+-doped gadolinium gallium garnet (GGG, Gd3Ga5O12) nanocrystalline host were investigated. Dominant blue/green emission was observed emanating from the 3P0 --> 3H4 transition after excitation using a wavelength of 457.9 nm. Continuous wave excitation into the 1D2 level of the Pr3+ ion at 606.9 nm transition produced blue upconversion luminescence spectra, ascribed to emission from the 3P1 --> 3H4 and 3P0 --> 3H4 transitions. The increase in the decay times of the observed transitions following excitation with 606.9 nm is indicative of the dominance of an energy transfer upconversion (ETU) mechanism relative to excited state absorption (ESA). Furthermore, blue, green and red upconversion emission was observed from the 3P0, 3P1 and 1D2 states following excitation into the 1G4 energy level with 980 nm. No change in the decay times of the emitting states was observed following excitation with a wavelength of 980 or 457.9 nm; hence, upconversion was determined to primarily occur through ESA. The luminescence properties of the nanocrystals are compared to a single crystal of GGG:Pr3+ (bulk) with an identical Pr3+ concentration (1%).