A comparative analysis of the interactions between the anionic sunset yellow dye with cationic, nonionic, and anionic surfactants

This work reports the comparative interaction of food dye sunset yellow (SY) with ionic, and nonionic surfactant mediums. Three different surfactants were utilized: the nonionic Pluronic. F-127 (F-127), the cationic Cetyl Pyridinium Bromide (CPB), and the anionic Ammonium Dodecyl Sulfate (ADS). The interactions were studied with the use of several methods, such as UV-visible spectroscopy, FTIR analysis, evaluating the zeta potential, dynamic light scattering (DLS), conductivity, fluorescence, and NMR spectroscopy. The binding constant values determined from UV-spectroscopic studies were 0.22 mM-1, 2.93 mM-1, and 0.02 mM-1 for SY-ADS, SY-CPB, and SY-F-127 systems, respectively. From the zeta-potential values, it is also inferred that the SY-CPB system is more stable than SY-ADS and SY-F-127 dye-surfactant combinations. In comparison to ADS and F-127 surfactant systems, the conductivity, fluorescence, and 1H/13C NMR experiments also showed that SY had a stronger interaction with CPB, a higher sensitivity, and a better affinity. The in silico docking study exhibited more interactive sites in the SY-CPB combination than the other two, corroborating the experimental findings. The DLS studies displayed size enhancement in the presence of ionic surfactants and shrinking of size in the nonionic combination. The results revealed that the cationic surfactant medium of CPB are promising formulations for the food industry's application of SY dye. To the best of our knowledge, this study is the first to report the interaction of SY with three distinct surfactant classes.