Evaluation of the critical micellar concentration of the components of the simulated intestinal media by UV-Vis and fluorescence spectrophotometry

Abstract

The importance of the critical micellar concentration (CMC) value of biological surfactants is of great interest for the development of new drugs as, between others, it helps to predict their pharmacokinetic behavior. Intestinal fluids comprise several components, one is sodium taurocholate. The formation of sodium taurocholate micelles allows the solubilization of lipophilic drugs and enhances their absorption capacity in the body. Therefore, this study was focused on the evaluation of the critical micellar concentration (CMC) value of this surfactant. In this work, the CMC of sodium taurocholate has been studied by UV-Vis spectroscopy and fluorescence at 25°C using neutral probes, so that they barely interfere with the formation of micelles. This study has been carried out in different media, changing the pH and ionic strength, and gradually getting closer to the desired biorelevant conditions. Next, several methods have been found to be able to calculate the value of the CMC. Here, the fluorometric method has resulted to be simpler and provides more accurate results than UV-Vis. It has been observed that CMC values are in the range of 10-4.5 mM and that ionic strength favors the micelle formation. Also, it has been noticed that the presence of components such as lecithin or oils make the surfactant aggregation and the micelle formation occur more gradually