title: Europium chelate (BHHCT-Eu3+) and its metal nanostructure enhanced luminescence applied to bioassays and time-gated bioimaging.
abstract: We report the use of europium chelate, 4,4'-bis(1'',1'',1'',2'',2'',3'',3''-heptafluoro-4'',6''-hexanedion-6''-yl)chlorosulfo-o-terphenyl-Eu(3+) (BHHCT-Eu(3+)), in silver nanostructure-enhanced luminescence and its application to bioassays and bioimaging. The highest luminescence intensity enhancement factor of BHHCT-Eu(3+) achieved in this study was about 11 times, while the simultaneously measured luminescence lifetime was reduced 2-fold. The luminophore photostability was also improved by a factor of 3. On the basis of these experimental results, we estimated the impact of silver nanostructures on the excitation and emission enhancement factors. Luminescence enhancement was demonstrated in two geometries: on planar glass substrates and on silica beads. In the biotin-modified IgG antibody assay the bead geometry provided slightly higher enhancement factor and greater sensitivity. Subsequently, we applied such bead substrates to time-gated luminescence imaging of Giardia lamblia cells stained by BHHCT-Eu(3+) where we observed improved brightness by a factor of 2. Such improved photostability and brightness of BHHCT-Eu(3+) in the presence of metal nanostructures are highly desirable for ultrasensitive bioassays and bioimaging, especially with time gating.
authors.affiliation: Department of Engineering and Physics, Macquarie University, North Ryde 2109 NSW, Australia.
authors.forename: Wei
authors.initials: W
authors.lastname: Deng
authors.forename: Dayong
authors.initials: D
authors.lastname: Jin
authors.forename: Krystyna
authors.initials: K
authors.lastname: Drozdowicz-Tomsia
authors.forename: Jingli
authors.initials: J
authors.lastname: Yuan
authors.forename: Ewa M
authors.initials: EM
authors.lastname: Goldys
mesh_terms: D002614:Chelating Agents; D003952:Diagnostic Imaging; D005063:Europium / Q000737:chemistry*; D005872:Giardia / Q000166:cytology; D007118:Immunoassay; D008163:Luminescent Measurements / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D005063:Europium