The effects of nano-TiO(2) (rutile) and non-nano-TiO(2) on the germination and growth of naturally aged spinach seeds were studied by measuring the germination rate and the germination and vigor indexes of aged spinach seeds. An increase of these factors was observed at 0.25-4% nano-TiO(2) treatment. During the growth stage, the plant dry weight was increased, as was the chlorophyll formation, the ribulosebisphosphate carboxylase/oxygenase activity, and the photosynthetic rate. The best results were found at 2.5% nano-TiO(2). The effects of non-nano-TiO(2) are not significant. It is shown that the physiological effects are related to the nanometer-size particles, but the mechanism by which nano-TiO(2) improves the growth of spinach seeds still needs further study.

Previous research on the biological and toxic effects of nano-TiO(2) particles on animals only limit to a single dose. However, the toxicity caused by single dose nano-TiO(2) does not truly represent ecological and health effects of nano-TiO(2) retained in the environment. In order to further evaluate the toxicity of nano-TiO(2) particles, nano-anatase TiO(2) (5 nm) was injected into the abdominal cavity of ICR mice everyday for 14 days and the coefficients of organs and serum biochemical parameters were investigated. The results showed that, with increasing doses of nano-anatase TiO(2), the coefficients of liver, kidney, and spleen increased gradually, while the coefficients of lung and brain decreased gradually, and the coefficient of heart had little change. The order of the titanium accumulation in the organs was liver > kidneys > spleen > lung > brain > heart. The serum biochemical parameters with lower dose of nano-anatase TiO(2) showed little difference compared with the control mice, while with higher dose of nano-anatase TiO(2), the indicators of liver function, such as alkaline phosphatase, alanine aminotransferase, leucine acid peptide, pseudocholinesterase, total protein, and albumin level, were enhanced significantly; the indicators of kidney function, such as uric acid and blood urea nitrogen, were decreased; the activities of aspartate aminotransferase, creatine kinase, lactate dehydrogenase, and alpha-hydroxybutyrate dehydrogenase, indicator of the myocardium function, were increased. The contents of triglycerides, glucose, and high-density lipoprotein cholesterol were significantly elevated. Taken together, nano-anatase TiO(2) in higher dose caused serious damage to the liver, kidney, and myocardium of mice and disturbed the balance of blood sugar and lipid in mice. The accumulation of titanium in the organs might be closely related to the coefficients of organs and the inflammatory responses of mice.

No abstract

The effects of nano-TiO2 (rutile) on the photochemical reaction of chloroplasts of spinach were studied. The results showed that when spinach was treated with 0.25% nano-TiO2, the Hill reaction, such as the reduction rate of FeCy, and the rate of evolution oxygen of chloroplasts was accelerated and noncyclic photophosphorylation (nc-PSP) activity of chloroplasts was higher than cyclic photophosphorylation (c-PSP) activity, the chloroplast coupling was improved and activities of Mg2+-ATPase and chloroplast coupling factor I (CF1)-ATPase on the thylakoid membranes were obviously activated. It suggested that photosynthesis promoted by nano-TiO2 might be related to activation of photochemical reaction of chloroplasts of spinach.

Previous research showed that nano-TiO2 could significantly promote photosynthesis and greatly improve growth of spinach, but we also speculated that an increase of spinach growth by nano-TiO2 treatment might be closely related to the change of nitrogen metabolism. The effects of nanoanatase TiO2 on the nitrogen metabolism of growing spinach were studied by treating them with nano-anatase TiO2. The results showed that nano-anatase TiO2 treatment could obviously increase the activities of nitrate reductase, glutamate dehydrogenase, glutamine synthase, and glutamic-pyruvic transaminase during the growing stage. Nano-anatase TiO2 treatment could also promote spinach to absorb nitrate, accelerate inorganic nitrogen (such as NO3--N and NH4+-N) to be translated into organic nitrogen (such as protein and chlorophyll), and enhance the fresh weight and dry weights.