Luminescence screening assays for the identification of sensitizers for lanthanides based on the controlled formation of ternary lanthanide complexes with DTPA-bisamide ligands.
Chem Asian J
; 5(3): 571-80, 2010 Mar 01.
Article
em En
| MEDLINE
| ID: mdl-20014090
ABSTRACT
The formation of ternary complexes of lanthanide-diethylenetriamine pentaacetic acid (DTPA)-bisamide complexes with different aromatic acids and their application in luminescent screening assays are presented. The europium complexes of DTPA-bisethylamide (BEA), DTPA-bisbutylamide (BUA), DTPA-bis(2-norbornyl) (NBA), and DTPA-bis(1-adamantyl) (ADA) have been isolated and the sensitization of emission upon 11 formation with aromatic acids has been studied by luminescence spectroscopy. The ternary complexes show stronger luminescence with picolinate (PCA) rather than phthalate (PTA) or benzoate (BZA), with the latter forming 12 complexes. Isophthalate and dipicolinate sensitizers do not show a 11 formation of the ternary complexes. Electrospray mass spectra show characteristic peaks that confirm the formation of the ternary complexes, and NMR spectroscopic studies demonstrated a conformational locking effect upon formation of the ternary complex. It is shown that europium complexes with bulkier amide arms provide complexes with stronger luminescence enhancement that is clearly attributable to the bulkiness of the amide arms. In a luminescence screening experiment, different substitutions on BZA and PCA were examined. Sensitizers with a long alkyl chain show greater luminescent enhancements than the nonsubstituted acids, which can be attributed to an "umbrella" effect of the alkyl chain that protects the europium luminescent center from the quenching of secondary high-energy vibrations, in particular O-H from water molecules. The same effect is presented for the quinoline derivatives as sensitizers. Quinoline derivatives with salicylate binding units were identified as the best sensitizers when combined with EuADA, which is even bulkier than EuNBA, with HQ-3COO showing a 50-fold enhancement of emission upon formation of 11 complexes.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Radiossensibilizantes
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Elementos da Série dos Lantanídeos
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Ácido Pentético
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Medições Luminescentes
Tipo de estudo:
Diagnostic_studies
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Prognostic_studies
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Screening_studies
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article