The Study Of Inhibition Of NiO Nanoparticles To Chlorella Sp. And Biological Interface Transformation

Nano-science,information science and life science have become the three main science fields in the 21th century.Because of the special physical and chemical properties(Quantum Size Effect,Small Size Effect,Quantum Tunnel Effect,Interface and Surface Effect),the nanoparticles have the high quality different from normal substances,and widely be applied to produce activities.Then they can be exposed to people.There is the potential impact to environment and people health,and this effect has attracted worldwide attention of scientific community and government.Growth conditions and micro-morphology are studied to reveal the inhibition of NiO nanoparticles(20 nm and 7 nm) to chlorella sp.,by contrast with Ni²⁺.The EC₅₀ value of NiO nanoparticles(20 nm) to chlorella sp.at 96 h is 31.4 mg/L by probability unit method,the NiO nanoparticles(7 nm) is 52 mg/L,but the EC₅₀ value of Ni²⁺ was 1.73 mg/L in the same conditions.The cell micro-morphology of chlorella sp.inhibited by NiO and Ni²⁺ were observed by Scanning Electron Microscopy(SEM) and Transmission Electron Microscopy(TEM).The chlorella sp.cell inhibited by the NiO (20 nm and 7 nm),the chloroplasts partly destroyed,photosynthesis hindered and anabolism slowed.The solution of chlorella sp.become light,after a proper long time, the color of the solution can be recovered.But the chlorella sp.inhibited by Ni²⁺,the chloroplast thylakoids are destroyed,some disappeared and the content of chlorophyll decreased,result in the decrease of photosynthesis and the great inhibition of cell growth.The nuclear membrane disrupted,some even disappeared.The nucleoli also disappeared.The results show that Ni²⁺ is far more toxic than NiO and the toxicity of 7 nm NiO is less toxic than that of 20 nm NiO.The biological transform between chlorella sp.and NiO nanoparticles is studied. The valence change of nickel is analyzed by using XRD,HRTEM and XPS.This shows that there is simple substance of nickel after the reaction between chlorella sp.and NiO nanoparticels,and it may deduce that the NiO nanoparticles react redox with certain organs of the chlorella sp..The further research of mechanism is expected.