Estudo da eficácia antimicrobiana de revestimentos de dióxido de titânio (TiO2) com propriedades fotocatalíticas

Abstract

In different fields, there is a need to ensure hygienically safe environments to ensure continuous protection by reducing microbial contaminants and pathogens. New solutions have been developed in recent years to solve this problem, among which photocatalytic systems are include. Pure health system consists of titanium dioxide with coatings (TiO2). The antibacterial activity of the photocatalytic TiO2 is based on the oxidation reaction produced by it’s irradiation using fluorescent lamps solar spectrum. The interaction between the radiation and the coating produces hydroxyl radicals and superoxide ions which are effective against bacteria. These materials can be applied in outdoor environments, indoor and public areas (parks, hospitals, schools, airports). In this study, the efficiency (microbial reduction) of materials such as PVC and coated ceramic TiO2 were tested against several important pathogens commonly encountered in clinical and food environments: Escherichia coli, Staphylococcus aureus, Acinetobacter baumannii, Listeria monocytogenes, Pseudomonas aeruginosa and Salmonella spp .. In order to understand the antimicrobial effect of PVC coating, the samples of this material with and without any coating, were analyzed by scanning electron microscopy. The images obtained show a "film" in the coating material, such feature is not observed in the material control. The test material was implemented in a canteen, sampling was performed over two weeks to assess the impact of the coating in a real situation. To determine the antimicrobial effectiveness of coatings of different matrices (PVC and ceramic) experimental tests were performed using the standard methodology described in ISO 22196: 2007. In general, 0.4 ml of a standard inoculum (105 CFU / cm2) of each organism was applied onto a fixed area of the material and subjected to light for 24 hours. The reduction of the microbial load during this period was monitored and the antibacterial efficiency determined. At the same time were also tested: a control not exposed to light with active coating and two controls with the same materials without active coating (exposed and not exposed to light). For all the organisms investigated, significant reductions were observed between 1 and 2 logarithmic cycles depending on the material and bacteria in study.

Date of Award	5 Sept 2016
Original language	Portuguese
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Maria Manuela Pintado (Supervisor) & Paula Teixeira (Co-Supervisor)