Selected Textural and Electrochemical Properties of Nanocomposite Fillers Based on the Mixture of Rose Clay/Hydroxyapatite/Nanosilica for Cosmetic Applications

Abstract

In order to improve the properties and characteristics of rose clay composites with acai, hydroxyapatite (HA), and nanosilica, the systems were mechanically treated. This treatment provides the preparation of better nanostructured composites with natural and synthetic nanomaterials with improved properties. The materials were characterized using XRD, nitrogen adsorption and desorption, particle sizing, zeta potential, and surface charge density measurements. For the systems tested in the aqueous media, the pH value of the point of zero charge (pHPZC) ranges from 8 to 9.9. However, the isoelectric point (pHIEP) values for all composites are below pH 2. This large difference between pHPZC and pHIEP is due to the complexity of the electrical double layer (EDL) and the relation of these points to different layers of the EDL. The tested samples as composite/electrolyte solutions are colloidally unstable. The toxicity level of the ingredients and release of anthocyanins as bioactive substances from acai in the composites were determined. The composites demonstrate an enhanced release of anthocyanins. There are some regularities in the characteristics depending on the type of components, morphology, and textural features of solids. The morphological, electrochemical, and structural characteristics of the components have changed in composites. The release of anthocyanins is greater for the composites characterized by minimal confined space effects in comparison with rose clay alone. The morphological, electrochemical, and structural characteristics allow us to expect high efficiency of composites as bioactive systems that are interesting for practical applications in cosmetics.

Keywords

• clay minerals
• hydroxyapatite
• acai
• electrical double layer