The application of citronella oil and citronellol as antibacterial ingredients in chitosan coatings for titanium surfaces

Abstract Novel chitosan-based coatings containing citronella essential oil (CEO) or citronellol additives were electrophoretically deposited on titanium substrates. The chemical composition and properties of the dispersed systems used for the deposition and process parameters to obtain robust coatings were determined. The increase in oil concentration in the dispersed systems had a negative impact on the adhesion strength of the coatings. The microstructure of the coatings consisted of droplets of CEO or citronellol distributed within and on the surface of the continuous chitosan matrix. The size of the droplets increased with an increase in the concentration of oil in the dispersed systems. Interestingly, the addition of CEO and citronellol to the chitosan matrix resulted in the formation of new hydrogen bonds between the components and the chitosan matrix. The mechanisms responsible for structural changes were identified. The coatings revealed moderate roughness of the surface. The coatings containing CEO exhibited slightly hydrophobic properties. Coatings containing citronellol were hydrophilic but with contact angles close to 90 deg. The coated titanium had weak bactericidal properties against S. aureus bacteria. The surfaces tested compared to the control did not show a significant cytotoxic effect. The coatings are interesting for further development of titanium surfaces with antimicrobial performance. Graphical abstract