Abstract The research reports the synthesis of α- MnO 2 and CuO nanoparticles obtained from laser ablation method. Based on the properties as semiconductors, the oxides as bactericity systems for Escherichia coli ATCC 11229 and Staphylococcus aureus ATCC 6538 have been tested. The influence on plasmon was evaluated, in relationship to the energy, time and wavelength of the laser used. The dispersion of nanoparticles for manganese oxide were in function of the energy, and its frequency oscillation is greater than copper oxide, due to the effects of charge transfer. The effect of a chiral organic compound was estimated in situ , generating stability and reproducible biocidal properties. Finally, it is important to mention that the biological activity was mediated by the semiconductor capacity. Control experiments will be necessary for to continue for the understanding of the mechanism.