Exploring the ability of the nalidixate to sensitize visible and near-infrared emitting lanthanide(III) cations.

Recently, a strong interest has been directed towards near-infrared (NIR) emitting lanthanide(III) compounds as they do possess complementary advantages in respect to organic molecules and semi-conductor nanocrystals, especially in the fields of biological analysis and imaging. To benefit from their emission, a key requirement to fulfill is the sensitization of lanthanide(III) cations with an appropriate chromophore. This condition is especially challenging to address for the lanthanide(III) cations emitting in the NIR.

Sensitive determination of proteins by its quenching effect on fluorescence of new terbium(III) complex.

It is found that in hexamethylenetetramine (HMTA-HCl) buffer pH = 7.8, proteins can quench the fluorescence intensity of new terbium(III) complex with 6-[(1-hydroxy-3-oxo-6,7-dihydro-3H,5H-pyrido[3,2,1-ij]quinoline-2-carbonyl)-amino]-hexanoic acid (L). Based on this, a sensitive fluorimetric method for the determination of proteins is proposed.

Sensitive luminescent determination of DNA using the terbium(III)-difloxacin complex.

The interaction of the terbium-difloxacin complex (Tb-DFX) with DNA has been examined by using UV-vis absorption and luminescence spectroscopy. The Tb-DFX complex shows an up to 85-fold enhancement of luminescence intensity upon titration with DNA. The long decay times allow additional detection schemes like time-resolved measurements in microplate readers to enhance sensitivity by off-gating short-lived background luminescence.

New luminescent terbium complex for the determination of DNA.

New terbium complexes of derivatives of 2-oxo-4-hydroxy-quinoline-3-carboxylic acid are reported, which are highly luminescent, water soluble and do not require luminescence enhancers. The triplet-state energy levels of the ligands, the relative quantum yields (QYs) and the excitation maxima of the respective terbium chelates were determined. The large luminescence enhancement of one of these complexes by nucleic acids was investigated and a mechanism of its interaction with DNA is proposed.