**3. Metal oxide nanoparticles as antimicrobial agents**

The resistance of microorganisms to the action of antimicrobial agents, especially antibiotics, is a serious public health problem, which has been a reason for the search and development of new antimicrobials through nanotechnology.

The manipulation on a nanoscale of metal oxide has provided new research in the pharmaceutical area due to the antimicrobial properties of these oxides, according to data revealed in *in vitro* studies [20, 21]. In this sense, the metal oxide NPs between 1 and 100 nm with different shapes allow their physical and chemical properties could become in some promise antimicrobial agents against infectious diseases for the recent findings about their interaction which has become of vital importance due to the increasing of infection diseases by bacterial resistance [22, 23].
