Multimetallic ruthenium(II) complexes as electrochemiluminescent labels.
Two homometallic complexes containing two and three ruthenium polypyridyl units linked by amino acid lysine (Lys) and the related dipeptide (LysLys) were synthesized and their electrochemical, spectroscopic, and electrochemiluminescence (ECL) properties were investigated. The electrochemical and photophysical data indicate that the two metal complexes largely retain the electronic properties of the reference compound for the separate ruthenium moieties in the two bridged complexes, [4-carboxypropyl-4'-methyl-2,2'-bipyridine]bis(2,2'-bipyridine)ruthenium(II) complex. The ECL studies, performed in aqueous media in the presence of tri-n-propylamine as co-reactant, show that the ECL intensity increases by 30% for the dinuclear and trinuclear complexes compared to the reference. Heterogeneous ECL immunoassay studies, performed on larger dendritic complexes containing up to eight ruthenium units, demonstrate that limitations due to the slow diffusion can easily be overcome by means of nanoparticle technology. In this case, the ECL signal is proportional to the number of ruthenium units. Multimetallic systems with several ruthenium centers may, however, undergo nonspecific bonding to streptavidin-coated particles or to antibodies, thereby increasing the background ECL intensity and lowering the sensitivity of the immunoassay.
Staffilani
Mara
M
IMC, Molecular Photonic Materials, Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands.
Höss
Eva
E
Giesen
Ulla
U
Schneider
Erich
E
Hartl
Frantisek
F
Josel
Hans-Peter
HP
De Cola
Luisa
L
D004563:Electrochemistry; D008163:Luminescent Measurements; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*; D013194:Staining and Labeling
D009942:Organometallic Compounds; D012428:Ruthenium