Deep eutectic solvents as modulator on the micellization behaviour of cationic surfactants and potential application in human serum albumin aggregation

Abstract Deep eutectic solvents (DESs) have been utilized in many important applications in interdisciplinary research areas including the investigation of self-assembly of surfactants. In present study, the micellization behaviour of two conventional cationic surfactants i.e., tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB) are investigated in aqueous DESs solutions with the help of surface tension, conductivity, UV–vis spectroscopy, fluorescence and dynamic light scattering (DLS) techniques. The synthesis of the DESs is done by simply mixing of choline chloride (ChCl) and urea/ethylene glycol (EG) in 1 : 2 mol ratio at 353 K temperatureand it is characterized by using FTIR technique. Various interfacial parameters and thermodynamic properties are evaluated by using tensiometric and conductometric methods. A noteworthy decrease in the critical micelle concentration (CMC) and increase in the aggregation number (Nagg) are observed in presence of DESs. Thus signifying that the micellization process of the surfactants is much favored in the DESs solutions and these are further supported by DLS results. DLS results show an increase in the micellar size for all the micellar systems in aqueous DESs solutions. More importantly, the micellar systems of the cationic surfactants within DESs solutions were also utilized for the study of their interaction with human serum albumin (HSA) to see how this albumin protein is behaving within the cationic micellar solutions in presence of DESs. UV–vis spectroscopic evidences show attractive results. It is noteworthy that the albumin protein HSA shows stronger binding affinity towards the DES-surfactants systems. The present work may further enhance the potential application of these neoteric green solvent systems composed of water-surfactant-DESs in the field of colloids, protein biophysics, nanoscience, which in turn will be highly applicable in the fields of synthesis, catalysis, and pharmaceutics etc.