Oligonucleotide hybridization monitored by surface plasmon enhanced fluorescence spectroscopy with bio‐conjugated core/shell quantum dots. Influence of luminescence blinking

The influence of the luminescence blinking of quantum dots on kinetic bio-sensing measurements is investigated. The hybridization kinetics of labelled DNA sequences with surface-immobilized DNA probes using surface plasmon enhanced fluorescence spectroscopy is employed to compare the behaviour of quantum-dot- and organic-chromophore-labelled DNA targets. The presented experiments show that quantum-dot labelled targets present apparent complex adsorption kinetics that can lead to inaccurate conclusions. By means of single quantum dot luminescence measurements and Monte-Carlo simulations, it is demonstrated that the anomalous adsorption kinetics observed with the quantum-dot labelled targets can be accounted for by the luminescence blinking statistics of the quantum dots. Thus, special attention should be paid when applying quantum dots as fluorescent labels in bio affinity studies in order to avoid wrong interpretations due to the special photo physical behaviour of these semiconducting nanocrystals. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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