Impact of coated TiO 2-nanoparticles used in sunscreens on two representative strains of the human microbiota: Effect of the particle surface nature and aging

摘要

Graphical abstractDisplay OmittedHighlights?Surface properties of coated TiO2-nanoparticles evolved during aging in model emulsions.?Impact on skin bacteria evaluated through two exposure scenarios mimicking use conditions.?Hydrophobic nanoparticles modified the physicochemical characteristics of model emulsions.?Hydrophobic nanoparticles favored the development of potential pathogenic bacteria.?Importance of the polarity of nanoparticles was highlighted regarding their impact on bacteria.AbstractThe impact of two differently coated TiO2-nanoparticles (NPs) was evaluated on two representative bacteria from the cutaneous microbiota (Staphylococcus aureusandPseudomonas fluorescens) in conditions of use. Particles were coated in order to exhibit either hydrophilic or hydrophobic behavior. A first exposure scenario within some fresh/aged model emulsions was developed in order to measure both the impact of the NPs presence and their surface nature during the emulsions conservation. Thanks to this protocol, it was demonstrated that, during aging, the hydrophobic NPs modified the physicochemical characteristics of the emulsions, such as the pH or the colloids sizes, and favored the development of potential pathogenic bacteria. A second scenario was then envisaged, aiming to mimic the exposition of the skin, especially of the cutaneous bacteria, to NPs. Tested NPs were extracted from emulsions with different aging, and results highlighted the importance of both the NP coating nature and their history in emulsion. The different NPs impacts on the bacteria growth were discussed and linked to their surface properties modifications during aging, as polarity and charges. Finally, through two exposition scenarios, this work highlights the major impact of the NPs surface properties on bacteria.]]>