Background: Nosocomial infections are important health problems and a cause of complications and death in hospitalized patients. This problem should be solved from the preventive angle, avoiding the spread of infections by designing disinfection methods based on the photocatalytic activity of semiconductor materials like Tin Oxide (SnO2). Methods: Antimicrobial activity of UV light was tested using Candida albicans ATCC10231 inoculation of SnO2 thin films by counting colony forming units (UFC). Interaction of UV light with SnO2 was analyzed by the Density Functional Theory (DFT) and the extension to Hubbard model (DFT+U) schemes to predict the electrons behavior in a subatomic level. Results: After exposure to UV light, C. albicans had a reduction of 36.5% of viable cells, and when SnO2 was included, cells were reduced by 60.2%. Measures of the electronics structure obtained by the first principle calculations under the DFT and DFT+U schemes showed that O-p orbitals mediate the oxidation process in the bulk semiconductor. By including the surface effects when cleaving the (1 0 0) plane, the three orbitals O-p, Sn-p, and Sn-s are the mediators. Conclusions: SnO2 films are promising antimicrobial coatings because UV light has a synergic activity with thin films, resulting in a faster disinfection.

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