ANTIMICROBIAL FLAME-MADE TIO2 NANOPARTICLE COATINGS PREPARED BY DIRECT THERMOPHORETIC DEPOSITION

This work reports the development of a one-step method for the production of antimicrobial protective coatings for aluminum surfaces with titania nanoparticles. Monodisperse, ultra-fine TiO2 nanoparticles were produced by flame aerosol synthesis and directly deposited by thermophoresis onto plates of aluminum alloy. A rotating disc, on which the substrates are mounted, repetitively passes through the flame. The rotational motion cools the substrates by convection, allowing particles to be deposited as films by thermophoresys. Submicron coatings of different thickness and porosity were produced by varying the total time of deposition. Different flame synthesis conditions were investigated in order to produce titania nanoparticles of different dimensions and phase composition. Pure anatase nanoparticles of 3.5 nm in diameter were produced in fuel-lean synthesis condition, while fuel-rich non-sooting condition was used to synthesize a mixture of rutile and anatase nanoparticle of 22 nm in diameter, rutile being the predominant phase. Atomic Force Microscopy was used to evaluate topological properties of the film, such as thickness, surface topography and roughness. A preliminary analysis of the antimicrobial activity of titania coatings was performed by means of Crystal Violet staining method, coupled with Scanning Electron Microscopy observation. Flame-synthesized TiO2 coatings exhibited the capability to inhibit the biofilms formation of different bacteria and fungi. The results are promising for using titania films as protective coatings for applications where an antimicrobial activity is required.