Sami Rtimi
Ecole Polytechnique Fédérale de Lausanne, Switzerland
Title: Antibacterial surfaces with presenting redox properties for indoor hospital surfaces
Biography
Biography: Sami Rtimi
Abstract
Surfaces coating is drawing attention as effective method to kill bacteria by contact in hospital facilities. Many coating methods
were studied and showed antibacterial capability. Many of them have the drawback of leaching out heavy metals, metal oxides,
antibiotics/antiseptics leading to the degradation of the environment and the ecosystem. Physical vapor deposition was used to
prepare metal oxides uniform, adhesive and ultra-thin coatings. In this direction, we provide insight into two different uniform
atomic-scale microstructures of Cu and Ti-oxides sputtered on polyethylene-based serum bags leading to fast bacterial inactivation
without losing the visibility of the liquid inside the bag. Co-sputtered (CuOx-TiO2-PE) consists mainly of CuO led to bacterial
inactivation kinetics within 20 min under very low intensity actinic/indoor light. This light is similar to the ones used in hospital
facilities and public places in Europe. The sequential sputtered (CuOx/TiO2-PE) consist mainly of Cu2O led to bacterial inactivation
within 90 minutes. By X-ray photoelectron microscopy (XPS), redox catalysis was observed to proceed during bacterial inactivation
for both coatings. The energetics and mechanism for the bacterial inactivation of E. coli on the co-sputtered and the sequential
sputtered catalysts are suggested. The Cu and Ti uniform distribution on the catalyst surface was mapped along the coating thickness
by wavelength dispersive spectrometry (WDS). By fluorescence stereomicroscopy the inactivation time of E. coli was found to be
in agreement with the times found by agar plating. The short-lived transients on the co-sputtered catalyst surface were followed by
femtosecond spectroscopy in the fs-ps region. By atomic force microscopy (AFM) the roughness of the co-sputtered (CuO) and
sequentially sputtered samples (Cu2O) were found respectively to present values 1.63 nm and 22.92 nm and the magnitude of the
roughness was correlated with the bacterial inactivation times. A deep understanding of the quantitative parameters controlling both
coatings leading to bacterial inactivation will be discussed.