The interaction of fluorescein isothiocyanate (FITC) and its two sugar analogues (viz., FITC-Dextran 40S and FITC-Dextran 2000S) with cetyltrimethylammonium bromide has been elucidated by absorption, fluorescence, Fourier transform infrared spectroscopy and fluorescence microscopic studies. It is seen that the emission of the probe molecules is uniquely sensitive to the changes in surfactant concentrations at a particular regime due to the formation of dye-surfactant supramolecular assembly. The formation of supramolecular assembly becomes effective at a lower surfactant concentration with increasing dextran size as a consequence of definite dye-surfactant interaction and could pave a facile strategy for designing hierarchical superstructures. (C) 2013 Elsevier B.V. All rights reserved.