Investigation On The Peroxidase-like Activity Of Vanadium Oxide

Since Fe oxides have been found to have biocatalytic activity similar to that of horseradish peroxidase（HRP）,a variety of Fe oxides and their complexes,including Fe₃O₄,Fe₂O₃,ZnFe₂O₄ et.al,have been reported to have similar catalytic activities.Recent studies have shown that the V₂O₅ nanowires and the VO₂ nanoparticles also have similar catalytic activity.In this thesis,the development of artificial mimetic enzymes was summarized firstly,and the metal oxide materials such as cerium oxide-based nano-materials and iron-based nano-materials were discussed in detail in the simulation of superoxide dismutase（SOD）,oxidase,catalase and peroxidase.Then,the characteristics and advantages of vanadium oxide in simulating peroxidase were briefly described,and the development prospect of vanadium oxide was prospected.On this basis,the effects of surface treatment and Ti doping on the microstructure and peroxidase-like activity of B-phase VO₂ nanoparticles（VO₂（B）powders）were studied:（1）The long rod-like VO₂（B）powder with uniform particles was prepared by hydrothermal synthesis,and the peroxidase-like activity of the powder was verified.The change of VO₂（B）activity was investigated by the process of 35℃constant temperature aerobic treatment.The catalytic mechanism of VO₂（B）enzyme,the source of peroxidase activity and the reasons of the change of VO₂（B）activity were studied.It was found that the activity of VO₂（B）peroxidase could be greatly enhanced by aerobic treatment,and the specific activity of VO₂（B）after aerobic treatment was about 6 times higher than that before treatment.It has a high activity characteristic which is significantly superior to other peroxidase-like enzymes and more similar to horseradish peroxidase（HRP）.The kinetic tests confirmed that the enzymatic catalytic mechanism is the sequential mechanism,and the active source is the VO₂（B）particle itself rather than the V-containing group.Combined with XRD,FTIR,SEM,XPS,Raman and other micro-analysis methods,the reasons for the significant increase of its activity can be attributed to the change of V-valence ratio caused by the entry of oxygen atoms and the local lattice adjustment caused by the entry of oxygen atoms into the surface.（2）Ti-doped VO₂（B）powder was prepared by using anatase TiO₂ with grain size3nm as doping source,and the change of peroxidase-like activity of Ti-doped VO₂（B）with doping amount was studied.The catalytic activity of Ti-doped VO₂（B）was compared with that of undoped VO₂（B）.The results of XPS showed that Ti existed in the lattice structure of VO₂（B）in the form of+4 valence.XRD,SEM,Raman showed that Ti-doped VO₂（B）maintains the basic crystal structure and rod-like morphology of B-phase.Long-term hydrothermal proof that Ti doping prevents the presence of other heterophase in VO₂（B）.The results of activity test show that Ti doping can effectively enhance the enzyme activity and stability of VO₂（B）.（3）The minimum detection limit and linear detection range of VO₂（B）powder in the detection of hydrogen peroxide and glucose were studied and measured.The specificity of VO₂（B）for substrate in the detection of glucose was confirmed by selective testing experiments.