A Photocatalytic TiO₂ Coating with Optimized Mechanical Properties Shows Strong Antimicrobial Activity Against...

Advanced technologies, such as antimicrobial coatings on food contact surfaces (FCSs), are critical to prevent the occurrence of food-contaminating bacteria. Titanium dioxide coatings were fabricated by the sol-gel method on stainless steel following an experiment consisting of eight different combinations of these synthetic parameters: type of protocol (method), amount of surfactant, aging time, spinning speed, and sintering temperature. Hardness and elastic modulus values of the eight coating combinations were assessed by nanoindentation, and their values were statistically analyzed to determine which protocol and sintering temperature were significant influencing factors. Additional experimental points were procured to obtain trends relating sintering temperature to hardness and elastic modulus. Within the experimental range studied, hardness monotonically increased with sintering temperature, reaching its maximum value at 595 °C, while elastic modulus attained a maximum value at 640 °C. These maxima's isotherms were overlapped on the coating's photocatalytic activity contour plot to explore which combinations of protocol, aging time, and sintering temperature yielded optimal photocatalytic activity, hardness, and elastic modulus. The optimized coating was tested against two representative foodborne pathogens, Escherichia coli O157:H7 and Staphylococcus aureus cells and their biofilms, and was characterized by nanoindentation, scanning electron microscopy, and X-ray diffraction. The properties of the coating, as found in this study, present evidence for its potential FCS applications.