Cinnamon oils and their main constituents as natural antibacterial agents of sodium alginate coatings electrophoretically deposited on austenitic stainless steel substrates - replication data

In this work, composite coatings made of sodium alginate and cinnamon essential oils or their main constituents were developed for biomedical applications by electrophoretic deposition (EPD) on stainless steel substrates. The EPD conditions including the chemical composition and electrokinetic properties of the emulsions, as well as the kinetics and mechanisms of deposition of single- and double-layer coatings, were investigated. Particular attention was paid to the treatment of substrates and the development of coatings with high adhesion strength. The double-layer coatings deposited in a two-step process, including EPD of an intermediate SA layer and an outer layer with the addition of essential oil, were found to exhibit the highest adhesion to the chemically-treated and anodically-oxidized substrates. Based on the FT-IR spectra, the mechanisms of interactions between the molecules of the introduced additives and the polymer chains were proposed. The coatings showed a hydrophilic character of the surface and slightly similar values of the polar and dispersive components for surface free energy. The surface roughness parameters for the coatings were several times higher than for the etched substrate. The corrosion resistance of the coated steel was slightly lower than that of the as-received and chemically-etched steel. The possible antimicrobial reaction of the coatings was evaluated using the quantitative serial dilution technique. Microbiological studies revealed that the nCA/SA//SA coatings had the highest bactericidal activity against Staphylococcus aureus ATCC 25923 bacteria. No significant bactericidal properties against Escherichia coli ATCC 25922 were observed on surfaces coated with alginate, nCBEO/SA//SA, and nCA/SA//SA. The viability of the MG-63 and FaDu cell lines for coatings with essential oils was low. The results obtained will be useful for the further development of such coatings to enhance the biological resistance to bacteria and reduce the cytotoxic response of stainless steel used for temporary bone implants.