The mechanochemically prepared compositions of skin care substances with silicates for medicinal and cosmetic applications

Abstract

Introduction: The active biological substances used in medicinal and cosmetic applications, are mainly
organic acids. The local contact effect of the protons located on the surface of their crystallites can irritate
the mucous membranes of the stomach and esophagus (medicines), or skin of the face (cosmetics). The
irritating effect of protons can be weakened either by grinding crystalline acid powders to nanoscale sizes,
or by neutralizing them. Organic acids are polymerized due to hydrogen bonds, which does not allow
them to be dispersed to nanometric sizes by traditional methods. It was previously shown that during
the mechanical activation of silicates, short-lived hydroxyl groups become available. Objective: The
purpose of this work is to study the possibility of neutralization of protons of organic acids during their
mechanochemical interaction with silicates. Methods: The IR spectroscopy, X-ray analysis and electron
microscopy methods were used for research. Results: It was shown by that organic acid is "grafted" to
the silicate surface due to neutralization of organic acid protons by hydroxyl groups of layered silicates,
opened during mechanical activation. This makes it possible to form highly dispersed composite structures
"organic acid/layered silicate" in dicarboxylic (carboxylic, aromatic, amino) acids - talc (pyrophyllite,
kaolinite) systems. Conclusions: Such mechanochemically synthesized composites, in which acid is
grafted to an inert carrier, in addition to high dispersion, provide a decrease in the acidity of the resulting
product. In the case of mechanochemical interaction of SiO2 with organic acids, the basic centers mainly
work on the surface of SiO2, which is opened during mechanical activation. Organic acids (hydroxo acids,
dicarboxylic, carboxylic, aromatic) are distributed in an extremely thin layer on the surface of silicon
oxide due to the "SiO2 — adsorption water — acid" bond. This allows to change the pharmacokinetics and
avoid ulcerogenic action and reduce the irritating effect of organic acids on the skin.