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Professor Sami Rtimi Plenary Speaker

Biography:

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Dr. Sami Rtimi is a photo-chemist with a strong background in surfaces’ engineering and microbiology. He was awarded a Ph.D. in Chemistry and Chemical Engineering from the Swiss Federal Institute of Technology (EPFL, Switzerland) and a Doctorate in Microbiology from the University of Carthage at Tunis (Tunisia). His expertise relates to the design, synthesis, evaluation and surface property characterization of antibacterial nanostructures for environmental and biomedical applications. His current research addresses coupling nanostructures for a targeted (bio)-response at the solid-air and solid-water interfaces showing potential practical applications. He published several papers in high impact journals in the field, numerous book chapters, patents and presented in several national and international conferences. He is editor in some journals, edited some special issues and books. He is member of many national and international societies/associations and serves as Advisory Panel for Elsevier since 2014.

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Redox catalysis for infections prevention in hospitals: Novelty and advances

 

Sami Rtimi (Ph.D)

Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.

 

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 min. 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.

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