title: Blue-emissive upconversion nanoparticles for low-power-excited bioimaging in vivo.
abstract: Water-soluble upconversion luminescent (UCL) nanoparticles based on triplet-triplet annihilation (TTA) were successfully prepared by coloading sensitizer (octaethylporphyrin Pd complex) and annihilator (9,10-diphenylanthracene) into silica nanoparticles. The upconversion luminescence quantum yield of the nanoparticles can be as high as 4.5% in aqueous solution. As determined by continuous kinetic scan, the nanoparticles have excellent photostability. Such TTA-based upconversion nanoparticles show low cytotoxicity and were successfully used to label living cells with very high signal-to-noise ratio. UCL imaging with the nanoparticles as probe is capable of completely eliminating background fluorescence from either endogenous fluorophores of biological sample or the colabeled fluorescent probe. In particular, such blue-emissive upconversion nanoparticles were successfully applied in lymph node imaging in vivo of living mouse with excellent signal-to-noise ratio (>25), upon low-power density excitation of continuous-wave 532 laser (8.5 mW cm(-2)). Such high-contrast and low-power excited bioimaging in vivo with a blue-emissive upconversion nanoparticle as probe may extend the arsenal of currently available luminescent bioimaging in vitro and in vivo.
authors.affiliation: Department of Chemistry and State Key Laboratory of Molecular Engineering of Polymers and Institute of Biomedicine Science, Fudan University, Shanghai 200433, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.forename: Tianshe
authors.initials: T
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.forename: Fuyou
authors.initials: F
authors.lastname: Li
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007834:Lasers; D049449:Luminescence; D051379:Mice; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes; D012822:Silicon Dioxide