Perturbations in the photophysical properties of isoxazole derivative of curcumin up on interaction with different anionic, cationic and non-ionic surfactants

Surfactants are organized assemblies that are often used as models for biomembranes and they can also act as solubilizing agents for various hydrophobic drug molecules. Isoxazole derivative of curcumin (IOC) is a potential drug molecule whose biological efficacy is limited due to its low aqueous solubility. In the present work, different supramolecular confined environments have been utilized to enhance the aqueous solubility of IOC. Besides this, they have also been used as models for studying the perturbations in the photophysical properties of IOC upon encapsulation inside them. To serve this purpose, three different surfactants have been chosen from each category of cationic (CTAB: Cetyltrimethylammonium Bromide), anionic (SDS: Sodium Dodecylsulfate) and non-ionic (TX-100: Trition X-100) surfactants. In order to study the mechanism of interaction of IOC with the three different types of surfactant molecules, various steady-state and time-dependent spectroscopic techniques have been employed. The change in the optical properties of IOC, such as; red or blue shifts in the absorption or emission maxima and increase in the intensities has helped in gathering information about the successful encapsulation of IOC inside the surfactant micelles as well as the effect of different confined environments on the photophysics of IOC. The time-dependent stability of all the three micellar systems divulged with the help of UV-Visible spectroscopy has revealed that IOC-surfactant micellar systems are extremely stable in nature even after 3 days. The large value of partition coefficient and increment in the quantum yield values as well as average lifetime certainly indicates the partitioning of the IOC molecules inside the organized assemblies of all the three surfactant micellar systems. Moreover, the effect of salt (NaCl) concentration has also been investigated on the steady-state and time-dependent photophysical properties of IOC encapsulated surfactant nano-micellar system. It could be observed that the salt has no effect on the photophysics of IOC even at very high concentration. Hence, the information obtained from the present work opens door for a relatively new research area where novel drug formulations of IOC could be designed and developed that would help the mankind in the near future. (C) 2021 Elsevier B.V. All rights reserved.