Fluorescent quantum dots as molecules sensors

Antoine Aubret, Anne Pillonnet, Julien Houel, Christophe Dujardin and Florian Kulzer (teams Luminescence and MNP), have published an article entitled «CdSe/ZnS quantum dots as sensors for the local refractive index» in the journal Nanoscale.

In this paper, the authors explore the potential of CdSe/ZnS colloidal quantum dots (QDs) as probes for their immediate dielectric environment, based on the influence of the local refractive index on the fluorescence dynamics of these nanoemitters. The viability of a conceptual framework based on a hard-sphere region-of-influence and the Bruggeman effective-medium approach is demonstrated. The authors find that all their measurements can be integrated into a coherent description, provided that the conceptualized point-dipole emitter is positioned at a distance from the substrate that corresponds to 
the geometry of the QD. Three theoretical models for the evolution of the fluorescence decay rate as a function of the local refractive index are compared, showing that the classical Lorentz approach (virtual cavity) is the most appropriate for describing the data. Furthermore, the observed sensitivity of the QDs is used to estimate the detection limit, expressed as the minimum number of traceable streptavidin molecules, of a potential QD-nanosensor based on fluorescence lifetime.

12/01/2016