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Molecular dynamics simulation studies on the concentration-dependent interaction of dodecyltrimethylammonium bromide with curcumin

Abstract Curcumin, a natural dietary polyphenol extracted from the roots of the plant Curcumin longa, possesses diverse therapeutic effects. The poor water solubility and instability of curcumin can be improved by encapsulation in surfactant micelles. In this paper, the interaction between curcumin and dodecyltrimethylammonium bromide (DTAB) in aqueous solution was studied by molecular dynamics simulation. Three systems were established by changing the number of added DTAB molecules to explore the interaction mode between curcumin and DTAB in different aggregation states. Distance distribution, number density distribution, electrostatic potential distribution and decomposition of energy were used to clarify binding structures and interaction mechanism. Before forming micelles, changes in the concentration of DTAB resulted in the formation of two different aggregation states, namely monomer and pre-micelle state. DTAB of two different aggregation states interacted with curcumin through electrostatic and hydrophobic interactions, respectively. When the surfactant concentration was above the critical micelle concentration (cmc), curcumin was solubilized into the micelle and located at the palisade layer as expected. The dynamic simulation results can provide a theoretical basis for experimental research and explain the interaction mode between them at the microscopic level. This will provide guidance for the use of surfactants in pharmaceutical formulations. GRAPHICAL ABSTRACT