Medical device-related infections represent a major healthcare complication, resulting in potential risks for the patient. Antimicrobial materials comprise an attractive strategy against bacterial colonization and biofilm proliferation. However, in most cases these materials are only bacteriostatic or bactericidal, and consequently they must be used in combination with other antimicrobials in order to reach the eradication condition (no viable microorganisms). In this study, a straightforward and robust antibacterial coating based on Phosphotungstate Ormosil doped with core-shell (SiO@TiO) was developed using sol-gel process, chemical tempering, and Ag nanoparticle photoassisted synthesis (POrs-CS-Ag). The coating was characterized by X-ray Fluorescence Spectroscopy (XRF), Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM) and X-ray Photoelectron Microscopy (XPS). The silver free coating displays low antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, in opposition to the silver loaded ones, which are able to completely eradicate these strains. Moreover, the antimicrobial activity of these substrates remains high until three reutilization cycles, which make them a promising strategy to develop self-sterilizing materials, such as POrs-CS-Ag-impregnated fabric, POrs-CS-Ag coated indwelling metals and polymers, among other materials.

Filho pela amizade, paciência, confiança e orientação durante o decorrer do trabalho.

Photochromic ormosil-phosphotungstate hybrid materials were prepared by immobilizing phosphotungstic acid, H 3 PW 12 O 40 , (HPW) in hybrid organic-inorganic ormosil matrices via sol-gel route, and the effect of addition of TiO 2 nanoparticles (NPs) on the photochromic response of HPW was studied. For measurement of the photochromic response and the bleaching kinetics, the resulting sol-gelderived ormosil-phosphotungstate hybrid materials with and without TiO 2 NPs were coated as thin films on glass substrate by dip coating. The hybrid films were characterized by scanning electron microscopy, Fourier transform infrared absorption spectroscopy, Raman spectroscopy and X-ray fluorescence spectroscopy. The addition of small amounts of TiO 2 was found to increase the photochromic response of the hybrid materials by as much as 277 % which is attributed to a possible interfacial electron transfer from the photoexcited TiO 2 to HPW. These highly UV-sensitive coatings can find useful applications in UV dosimeters and smart windows.Electronic supplementary material The online version of this article (

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