title: Stable and highly fluorescent europium(III) chelates for time-resolved immunoassays.
abstract: Derivatives of 4-[2-(4-isothiocyanatophenyl)ethynyl]-2,6,-bis{[N,N-bis(carboxymethyl)-amino]methyl}pyridine europium(III) (1) bearing one (6) or two (7) additional iminodiacetate coordinating arms have been synthesized. 6 and 7 were significantly more stable than 1 as evidenced by competition experiments with ethylenediaminetetraacetic acid (EDTA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). While the luminescence quantum yield of 1 remained modest, the other two complexes displayed substantial luminescence efficiency. The introduction of a supplementary iminodiacetate arm in 6 brought important improvements to both the stability and the luminescence properties of the Eu complex. In contrast, although 7 is more luminescent than 1, the introduction of a second iminodiacetate coordinating arm brings no further benefit on the photophysical properties. The most promising results were obtained with the nine-dentate chelate 6 and its Eu complex, which was conjugated to biotin and applied within the frame of a bioaffinity immunoassay of human C-reactive protein.
authors.affiliation: Laboratory of Biophysics, University of Turku, FI-20014 Turku, Finland. qiwang@utu.fi
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Katia
authors.initials: K
authors.lastname: Nchimi Nono
authors.forename: Markku
authors.initials: M
authors.lastname: Syrjänpää
authors.forename: Loïc J
authors.initials: LJ
authors.lastname: Charbonnière
authors.forename: Jari
authors.initials: J
authors.lastname: Hovinen
authors.forename: Harri
authors.initials: H
authors.lastname: Härmä
mesh_terms: D002097:C-Reactive Protein / Q000032:analysis; D002614:Chelating Agents / Q000737:chemistry*; D004355:Drug Stability; D004492:Edetic Acid / Q000737:chemistry; D005063:Europium / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013997:Time Factors
chemical_list: D002614:Chelating Agents; D005456:Fluorescent Dyes; D006573:Heterocyclic Compounds, 1-Ring; D009942:Organometallic Compounds; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; D005063:Europium; D002097:C-Reactive Protein; D004492:Edetic Acid