Slow solvent relaxation dynamics of nanometer sized reverse micellar systems through tryptophan metabolite, kynurenine

Exploration of environmental dynamics using intrinsic biological probe tryptophan is very important; however, it suffers from various difficulties. An alternative probe, kynurenine (KN), has been found to be an efficient probe for the ultrafast dynamics in the biological environment ( 1 ] J. Phys. Chem. B., 114, 15236–15243). In the present study, we have investigated the efficacy of KN for the exploration of relatively slower dynamics of biologically relevant environments. A detailed investigation involving UV–Vis, steady‐state/time‐resolved fluorescence spectroscopy and Förster resonance energy transfer (FRET) studies on KN compared to a well‐known solvation probe, H33258, a DNA‐minor groove binder in a model nonionic reverse micelle reveals that ultrafast internal conversion associated with the hydrogen‐bonding dynamics masks KN to become a dynamical reporter of the immediate environments of the probe.