| Nanotechnology, which was born in1980s, has presented an amazing development trend and profound influence in many areas. Nanotechnology is changing social life, industries and agriculture in different ways. Because a large quantity of nanomaterials (NPs) will be produced and used, there are serious concerns over their health and environmental risks once they are released to the environment. Because of the big surface area, NPs could interact with a large volume of substances in the environment, such as environmental pollutants. After interaction with pollutants, NPs could change the mobility, biological activity and environmental risks of pollutants. Moreover, nanomaterial/pollutants complex may enter body through food or water. It was revealed that most of the adsorbtion onto NPs was reversible. It imply the potential release of organic chemicals after intake by animals or human. In this case, CNTs act like pollutant collectors and thus pose high health risk. Thus, the evaluation of toxicity of naomaterial/pollutants complex is imperative.On the other hand, because of the high adsorption capability, NPs could be used as superior sorbents for environmental treatment. It has been reported that TiO2nanoparticles, magnetic nanoparticles, carbon nanotubes are efficient pollutants adsorbents. However, the widely use of NPs in water treatment was restricted by the question whether NPs/pollutants complex could cause secondary contamination, because that the NPs will leak to the environment inevitbly in the process. The complex toxicity has been one of the obstacles for NPs’environmental application.Carbon nanotubes (CNTs) are quasi one-dimensional carbon NPs with hollow cylindrical structure. They have been successfully applied to battery electrode, plastics, dye, adhesives, sewage treatment, medicine etc. Because of the superior physical and chemical characteristics. In biomedicine area, CNTs not only can be used for cancer therapy, but also used as drug delivery through various covalent or noncovalent modification on their benzene riching surface. It can increase cancer cells mortality with low toxicity on normal cells, which makes it one of the most potential anti-cancer drugs in cancer therapy. According to the reports, up to a hundred billion of CNTs are produced in the world every year. CNTs may spread to the environment in the form of dust inevitably. Because CNTs possess fibrous shape with high aspect ratio, large accessible external surface area, well developed mesopores, and chemical and thermodynamic stability, CNTs hold superior removal capacities of environmental pollutants. Research has proved that CNTs have good removel ability on organic pollutants, heavy metal, fluoride, radioactive compounds and biological contaminants.Bisphenol A (BPA) as a common endocrine disrupter in environment, usually comes from degradated plastics and leaches from landfills. As an endocrine disrupter, BPA has effects on liver, brain, reproductive system, the immune system and metabolic system. It is proved that CNTs has excellent adsorption ability on BPA. Because of its "butterfly" structure, BPA has a unique ability to adsorb on the curvature surface of CNTs. BPA can wedge into the groove and interstitial region of CNTs bundles or aggregates. The π-π electron donor-acceptor system is an important mechanism for the adsorption of BPA on CNMs, and the interaction is strong. It also found desorption hysteresis is significant. The high adsorption capacity and strong desorption hysteresis of BPA on CNTs indicate that CNTs are potential adsorbent for water treatment.In consideration of the facts above, and the poison sensitivity during embryonic period, we choose MWCNT-COOH, BPA as the representatives of NPs and pollutants, to study the toxicity of MWCNT-COOH/BPA complex (Hereinafter referred to as Complex) on male offspring when through oral exposure to mather mice during perinatal period, and compared with mouse exposed to MWCNT-COOH or BPA only. Through primary evaluation of the complex, we can illuminate to the understanding of CNTs environmental risks. This also provides useful information on the safty of CNTs applied in environmental treatment. This paper evaluated the toxicity of NPs/pollutants construct in vivo for the first time, which lead the way for complex assessment.The experiment section of this text can be divided into three parts for illustration. The first part, we described the preparation of MWCNT-COOH/BPA complex. We found that the absorbance of the complex was around37μg (BPA)/lmg (MWCNT-COOH). The injection sample of the complex was stable as the desorption proportion keeps about1%in4h. The second part, we evaluated maternal toxicities of BPA, MWCNT-COOH and Complex. It was revealed that no behaviour disorders were observed among administration in all dams. Compared with control group, dams of all treated groups exhibited a slight increase in body weight during later gestation period. Complex high dose group shows raised neonatal numbers, whereas other treated groups show no changes in both neonatal numbers and sex ratio. These data shows that, BPA, MWCNT-COOH, Complex have slight effect on mather mice. The third part was the toxicity assessment of BPA, MWCNT-COOH and Complex on male offsprings. This part evaluated the influences from three aspacts.(1) Effects on body weight and organ index. Adult male mice body weight are slight inhibited in all treated groups compared with control group, which suggest adverse effect of the three materials on male offspring. Furthermore, increased kidney index in all dose groups of Complex was observed which demonstrated its adverse effect on kidney.(2) Determination of serum hormones (LH, FSH, Testosterone) level and MDA level in testis. From the research of hormone level, we got that exposure of BPA, MWCNT-COOH and Complex during embryo and lactation period can disturb hormone level in male offsprings with a dose independent way. Among all groups, BPA has the most strong effect in hormone levels and the Complex are next. MWCNT-COOH only have litte effect on LH level. The results show that BPA and Complex can disrupt the hypothalamic-pituitary-testicular axis and threat sperm formation in the testes. In analysis of MDA in testis, we found significantly increased MDA level in BPA high dose group, illustrating oxidative damage occurred in testicular tissue. Moreover, other treated groups all exhibit different degrees of MDA increase, which indicated they have potential oxidative damage to testis.(3) Histopathology effect of BPA, MWCNT-COOH and Complex on heart, liver, spleen, lung, kidney and testis. We found that all dose of the three materials have no effect on the pathology of heart, spleen and lung, while obvious influence was found the liver and kidney. All the three materials could not cause pathological changes in testisIn conclusion, MWCNT-COOH/BPA complex still have obvious toxicity compared with BPA. This reminds us the risk of nanotubes applied in environmental treatment. |
PDF Full Text Request