Study of proteinous and micellar microenvironment using donor acceptor charge transfer fluorosensor N,N-dimethylaminonaphthyl-(acrylo)-nitrile

Interaction of charge transfer fluorophore N,N-dimethylaminonaphthyl-(acrylo)-nitrile (DMANAN) with globular proteins Human Serum Albumin (HSA) and Bovine Serum Albumin (BSA) brings forth a marked change in the position and intensity of band maxima both in case of absorption and fluorescence spectra. Spectroscopic approach has been elaborately implemented to explore the binding phenomena of the probe with HSA and BSA and it is found that the extent of binding of the probe to both serum albumins is similar in nature. Steady state fluorescence anisotropy values, fluorescence quenching study using acrylamide quencher and Red Edge Excitation Shift (REES) help in drawing reliable conclusions regarding the location of the probe molecule within the hydrophobic cavity of the proteins. An increase in fluorescence lifetime of the probe molecule solubilized in both the proteinous media also indicate that the probe is located at the motionally restricted environment inside the hydrophobic cavity of proteins and hence non-radiative channels are less operative than in the bulk water. Similarly, the variation of position and intensity of the emission maxima of DMANAN solubilized in micellar medium of Sodium Dodecyl Sulphate (SDS) also predicts well the critical micellar concentration (CMC) and polarity of micellar microenvironment.