ZnO Nanoparticle Induced Chloride Ion Release From Garlic Root Tip

The applications of nano-materials are expanding rapidly. The reason of this rapid development is closely related to their unique physical and chemical properties. Therefore, in the future development, the emphasis on the prospects for the application of nano-materials can not be ignored. Among many nano-particals of metal oxide, ZnO nano-particle is one of the most widely used nano-materials. Because the products containing ZnO nano-particles are closely related to our lives, so people began to become increasingly concerned about the potential toxicity of ZnO nano-particles. In recent years, the results about nano-ZnO suggest that ZnO nano-particles have the potential toxicity to plants, animals, as well as ecology. Although there have been many researches on the bio-safety of ZnO nano-particles, the impact of ZnO nano-particls on the metabolism of chlorine ion is not in the very focus. In this paper, focused on the on the ZnO nano-particle induced chlorine ion release from garlic root tips.The ZnO nano-particles used in this study is prepared by sol-gel method, the average size of which is about5nm. In order to measure the level of chlorine ion around the root tips, we designed and fabricated a kind of Ag/AgCl micro-electrode, and obtained its working curve.Our previous studies showed that the existence of ZnO nano-particles obviously inhibited the growth of garlic root tips. Because chloride ion is one of the most important ions in maintaining cellular activities, the existence of ZnO nano-particles may also affect the metabolism of chloride ions. Our current studies do confirmed this proposition. The garlic root tips were cultivated in different concentrations of ZnO nano-particle suspensions,10mg/L,30mg/L,50mg/L and70mg/L, respectively. Compared with those root tips cultivated in pure de-ionized water, the chloride ion levels around the root tips were found to rise remarkably, indicating an chloride ion release. This ZnO nano-particle induce chloride ion release was enhance by the increase of the concentration of ZnO nano-particles. When the concentration of ZnO nano-particles reached70mg/L, the concentration of chloride ions around the garlic root tip also reached its highest level. These results may explain in part the mechanism of the nano-toxicity of ZnO nano-particles on garlic root tips.