¹Lomonosov Moscow State University, Moscow, Russia
²Scientific and Educational Mathematical Center, Kovalevskaya Northwestern Center for Mathematical Research, Pskov State University, Pskov, Russia

Abstract. Quaternary ammonium compounds exhibit surfactant properties and are widely used to clean a variety of surfaces. Being cationic detergents, quaternary ammonium compounds can disrupt cell walls and lyse the membranes of pathogenic microorganisms, exhibiting antimicrobial properties in alkaline environments. Quaternary ammonium compounds such as cetyltrimethylammonium bromide and cetyltrimethylammonium chloride have emulsifying and antistatic properties and are included in many cosmetic products. After use, quaternary ammonium compounds enter wastewater, treatment plant sludge, and disperse into the environment, posing a serious threat to aquatic and soil life. The high content of negatively charged lipids in the functional membranes of photosynthetic organisms makes them potential targets for quaternary ammonium compounds. In this study, we applied coarse-grained molecular modeling to analyze the molecular mechanisms of interaction between cetyltrimethylammonium bromide, a cationic surfactant widely used in cosmetics, and biological membranes containing negatively charged lipids. Unlike several cationic antiseptics that cause a decrease in lipid mobility, i.e. an increase in the viscosity of such membranes, cetyltrimethylammonium bromide did not have such effects when incorporated into membranes. The data obtained indicate that cetyltrimethylammonium bromide may have reduced ecotoxicity, including against autotrophic microorganisms.

Key words: quaternary ammonium compounds, surfactants, biological membranes, negatively charged lipids, Brownian dynamics, coarse-grained molecular modeling