Thermal analysis applied to the characterization of nanostructured materials

Abstract

Solar ultraviolet radiation is one of those responsible for accelerating the oxidative processes, both in skin and hair, through the generation of reactive oxygen species (ROS). This can be prevented or reduced using antioxidants such as flavonoids. The concentration of flavonoids into cosmetic formulations is limited by its low solubility. However, higher concentrations may be incorporated in nanostructures. In addition, flavonoids can also have the function of stabilizing such nanostructures, yielding the so-called Pickering emulsion. The nanoemulsions can be characterized by various techniques, among which stands out the thermal analysis, comprising thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). TG provides information on the thermal decomposition of organic compounds or processes of hydration/dehydration. The DSC technique is usefull in order to determine the temperature and enthalpy/entropy change associated with chemical phenomena, such as interaction between substances, a widely used method for determination of incompatibility between drugs and excipients. Characterization of nanoemulsions by thermal analysis is little explored, despite its high potential for use as a way to study the possible (negative or positive) interactions between components. The objective of this work is to characterize the thermal profile of nanoemulsions containing the flavonoid quercetin, evaluating possible interactions between flavonoid and surfactants and to determine whether the formulation developed is a pickering emulsion. (AU)