Innovative transparent non-scattering TiO2 bactericide thin films inducing increased E. coli cell wall fluidity

This study presents the first account for transparent, non-scattering TiO2 films on radio-frequency (RF) plasma and ultraviolet light in the C-spectral region (UVC) pretreated polyethylene (PE). These pretreatments allow the PE to bind higher amounts of TiO2 necessary to induce E. coli inactivation in the minute range under simulated sunlight irradiation. The uniform TiO2 film was sputtered by direct current magnetron sputtering (DC). These higher TiO2 loadings were necessary to obtain faster bacterial inactivation kinetics on the PE films. The peak shifts in the stretching of the symmetric and asymmetric vibrational infrared spectra of the CH groups were followed during the time of bacterial inactivation (60 min). This time was concomitant with the time required for the hydrophobic to hydrophilic transition on PE-TiO2. The production of malondialdehyde (MDA) was observed during E. coli loss of viability. PE pretreatment led to a significant increase in the TiO2 loadings on the PE surface as shown by X-ray fluorescence (XRF), X-ray-diffraction (XRD) by X-ray photoelectron spectroscopy (XPS).