title: Visible-light-excited and europium-emissive nanoparticles for highly-luminescent bioimaging in vivo.
abstract: Europium(III)-based material showing special milliseconds photoluminescence lifetime has been considered as an ideal time-gated luminescence probe for bioimaging, but is still limited in application in luminescent small-animal bioimaging in vivo. Here, a water-soluble, stable, highly-luminescent nanosystem, Ir-Eu-MSN (MSN = mesoporous silica nanoparticles, Ir-Eu = [Ir(dfppy)2(pic-OH)]3Eu·2H2O, dfppy = 2-(2,4-difluorophenyl)pyridine, pic-OH = 3-hydroxy-2-carboxypyridine), was developed by an in situ coordination reaction to form an insoluble dinuclear iridium(III) complex-sensitized-europium(III) emissive complex within mesoporous silica nanoparticles (MSNs) which had high loading efficiency. Compared with the usual approach of physical adsorption, this in-situ reaction strategy provided 20-fold the loading efficiency (43.2%) of the insoluble Ir-Eu complex in MSNs. These nanoparticles in solid state showed bright red luminescence with high quantum yield of 55.2%, and the excitation window extended up to 470 nm. These Ir-Eu-MSN nanoparticles were used for luminescence imaging in living cells under excitation at 458 nm with confocal microscopy, which was confirmed by flow cytometry. Furthermore, the Ir-Eu-MSN nanoparticles were successfully applied into high-contrast luminescent lymphatic imaging in vivo under low power density excitation of 5 mW cm(-2). This synthetic method provides a universal strategy of combining hydrophobic complexes with hydrophilic MSNs for in vivo bioimaging.
authors.affiliation: Department of Chemistry, Fudan University, Shanghai 200433, PR China.
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Fudan University, Shanghai 200433, PR China. Electronic address: shimei@fudan.edu.cn.
authors.forename: Mei
authors.initials: M
authors.lastname: Shi
authors.affiliation: Department of Chemistry, Fudan University, Shanghai 200433, PR China.
authors.forename: Lingzhi
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Chemistry, Fudan University, Shanghai 200433, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.affiliation: Department of Chemistry, Fudan University, Shanghai 200433, PR China. Electronic address: fyli@fudan.edu.cn.
authors.forename: Fuyou
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Chemistry, Fudan University, Shanghai 200433, PR China.
authors.forename: Chunhui
authors.initials: C
authors.lastname: Huang
mesh_terms: D000818:Animals; D056831:Coordination Complexes / Q000737:chemistry / Q000633:toxicity; D005063:Europium / Q000737:chemistry / Q000633:toxicity; D006367:HeLa Cells; D006801:Humans; D007495:Iridium / Q000737:chemistry / Q000633:toxicity; D008027:Light; D049408:Luminescent Agents / Q000737:chemistry / Q000633:toxicity; D008163:Luminescent Measurements; D051379:Mice; D008819:Mice, Nude; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity; D012822:Silicon Dioxide / Q000737:chemistry / Q000633:toxicity; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D056831:Coordination Complexes; D049408:Luminescent Agents; D007495:Iridium; D005063:Europium; D012822:Silicon Dioxide
keywords: Europium(III) complex; Luminescent bioimaging; Mesoporous silica nanoparticles; Nano-confined; Phosphorescent iridium(III) complex