Stresses Exerted by ZnO, CeO2 and Anatase TiO2 Nanoparticles on the Nitrosomonas Europaea

Recent studies have shown that nano-bio interfaces are the most complex and the least understood. Notably, nanotoxicity of these nanoparticles is not even well recognized. In this work, we examined the toxic effects of different nanoparticles on bacteria cells (Nitrosomonas europaea). The four nanoparticles involved are: 25 nm anatase TiO(2), 200 nm anatase TiO(2), ZnO and CeO(2) particles. These particles will have different electrical charges in the cell cultivating media. It has been observed that even with only 4 h of dosing, all of the particles caused apparent morphological damage to the cells. Experimental results suggest that ZnO particles exert the stress on cells by its dissolution and releasing of Zn(2+) ions. The TEM and AUC (analytical ultracentrifuge) result suggest that cells become heavier in presence of CeO(2) and TiO(2) particles. No visible clear intrusions of bulk nanoparticles were observed. However, both the analytical ultracentrifuge and TEM results show that cells are heavier when being damaged.