Evaluation of antimicrobial activity of ZnO based nanocomposites for the coating of non-critical equipment in medical-care facilities

Nosocomial infections are quite common in medical facilities environment and the highest percentage is caused by bacteria. The transmission of such infections is often made by direct contact with non-critical surfaces. Therefore, it is important to develop surfaces able to inhibit microbial adhesion and proliferation. In this work monolithic ZnO and copper and carbon nanocomposite ZnO thin films were studied to evaluate their antimicrobial activity for the coating of non-critical surfaces at medical care facilities. ZnO-Cu functioned as reference for the comparison of the ZnO-C thin films performance. The coatings were deposited by r.f. magnetron sputtering technique and were thoroughly characterized, before the antimicrobial tests against two distinct bacteria: Pseudomonas aeruginosa and Staphylococcus aureus. The tests were conducted in liquid and solid culture media under three different light incubation conditions. The results indicate that the antimicrobial properties of ZnO thin films were enhanced by the incorporation of C and Cu. The integration of carbon in ZnO produced similar results to copper doped thin films, allowing to produce metal-free surfaces that do not induce metal bacteria resistance.