Eliminating the contribution of interfering compounds is a key step in chemical analysis. In complex media, one possible approach is to perform a preliminary separation. However such a purification step is often demanding, long, and costly, and may also considerably alter the properties of interacting components of the mixture (e.g. in a living cell). Hence, for varioussignificant applications (e.g. biological assays), there is a strong interest for developing non-invasive protocols for quantitative analysis in complex mixtures. Using photoswitchable probes as labeling and titration contrast agents, we demonstrate that the association of a modulated monochromatic light excitation with a kinetic filtering of the overall observable that exploits the probe dynamic information is much more attractive than constant excitation to quantitatively read-out the contribution from a target probe under adverse conditions. An extensive theoretical framework enabled us to optimize the out-of-phase concentration first-order response of a photoswitchable probe to light modulation by appropriately tuning the average light intensity and the radial frequency of the light modulation. Thus, we can selectively and quantitatively extract from an overall signal the contribution from a target photoswitchable probe within a mixture of species, photoswitchable or not.1 This simple titration strategy is more specifically developed in the context of fluorescence imaging, which offers promising perspectives.2References: 1. J. Querard, A. Gautier, T. Le Saux, L. Jullien, Out-of-phase titration after modulation of activating light (OPTIMAL) for selective and quantitative detection, submitted; 2. J. Querard, T. Markus, M.-A. Plamont, C. Gauron, P. Wang, A. Espagne, M. Volovitch, S. Vriz, V. Croquette, A. Gautier, T. Le Saux, L. Jullien,Out-of-phase imaging after optical monochromatic modulation, submitted.

Out-of-phase titration after modulation of activating light (OPTIMAL) for selective and quantitative detection

248th National Meeting (2014)

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