title: The impact of shell host (NaYF₄/CaF₂) and shell deposition methods on the up-conversion enhancement in Tb³⁺, Yb³⁺ codoped colloidal α-NaYF₄ core-shell nanoparticles.
abstract: Lanthanide doped, up-converting nanoparticles have found considerable interest as luminescent probes in the field of bio-detection. Although the nanoparticles (NPs) have already been successfully applied for fluorescent bio-imaging and bio-assays, the efficiency of the up-conversion process seems to be the bottle-neck in rigorous applications. In this work, we have shown enhancement of the up-conversion in colloidal α-NaYF₄:Yb(3+), Tb(3+) doped nanocrystals owing to passivation of their surface. We have studied quantitatively the influence of the shell type (NaYF₄ and CaF₂), its thickness, as well as the shell deposition method (i.e. single thick shell vs. multi-layer shell) on the luminescent properties of the nanoparticles. The results showed that up to 40-fold up-conversion intensity enhancement may be obtained for the core-shell nanoparticles in comparison with the bare core nanoparticles, irrespective of the shell type and deposition method. Moreover, the suitability of the NaYF₄:Yb(3+), Tb(3+) core-shell NPs for multi-color emission and spectral multiplexing has been presented.
authors.affiliation: Wroclaw Research Centre EIT+, Stablowicka 147, 54-066 Wroclaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Prorok
authors.forename: Artur
authors.initials: A
authors.lastname: Bednarkiewicz
authors.forename: Bartlomiej
authors.initials: B
authors.lastname: Cichy
authors.forename: Anna
authors.initials: A
authors.lastname: Gnach
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Misiak
authors.forename: Marcin
authors.initials: M
authors.lastname: Sobczyk
authors.forename: Wieslaw
authors.initials: W
authors.lastname: Strek
mesh_terms: D001681:Biological Assay; D002124:Calcium Fluoride / Q000737:chemistry; D003102:Colloids / Q000737:chemistry*; D004735:Energy Transfer; D005459:Fluorides / Q000737:chemistry; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D055095:Optics and Photonics; D012997:Solvents; D014269:Trifluoroacetic Acid / Q000737:chemistry; D014961:X-Ray Diffraction; D015019:Yttrium / Q000737:chemistry
chemical_list: D003102:Colloids; D028581:Lanthanoid Series Elements; D008024:Ligands; D012997:Solvents; D015019:Yttrium; D014269:Trifluoroacetic Acid; D002124:Calcium Fluoride; D005459:Fluorides