Infoscience

Thesis

Thin films for Healthcare Acquired Infections (HAIs) prevention: materials preparation, testing and characterization

This thesis addresses the preparation of antibacterial surfaces for hospital facilities taking biomedical thin polymer films, textiles and catheter as probes. Magnetron sputtering is used to apply the coatings leading to fast bacterial inactivation in the dark and under low intensity light on the selected substrates. These coating are designed and prepared to achieve fast bacterial inactivation to avoid biofilm formation on textiles and polymer films and later on the catheter surface. The infection due to catheters is one of the major problem leading to catheter associated infections (CAIs). The design, preparation, testing and the characterization of the surface properties of uniform and adhesive TiO2,TiO2/Cu, Ag, Cu-films presenting fast bacterial inactivation kinetics on textiles and catheters by up to date HIPIMS and DCMS/DCPMS has been addressed very sparsely until now mainly on 3D objects. No evidence for Ag-Cu coating applied by sputtering covering uniformly the entire catheter surface has been reported up to this date. A modification of the sputtering unit was carried out to coat 3D objects and is one of the main novelties reported in this thesis. The antimicrobial activity was tested on antibiotic resistant bacteria Methycillin resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) alone or jointly representing an important focus of infection by themselves or in the form of pathogenic biofilms in hospital facilities. The bacterial inactivation kinetics was investigated in details under low intensity light and in the dark. The active part of the catheter remains under the patient skin (in the dark). Ag/Cu-has been selected since fast bacterial inactivation proceeds in with a quasi-instantaneous kinetics inducing a cytotoxicity below the limit authorized by the sanitary regulations for mammalian cells. These coatings are also well tolerated by osteoblasts. The sputtered films leading to fast bacterial inactivation and showing low cytotoxicity consisted mainly of TiO2, Cu-TiO2, and Ag/Cu films on 2D surfaces and on catheters with 3D-geometry. This is the first report for materials of this kind, their evaluation and surface properties.

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