The Application Of Electrochemical Biosensor Based On Hybrid Of Ionic Liquids-based Polysome/Gold Nanoparticles

In recent decades,various detection assays have been developed to cope with the challenges of public security and medical test.Among kinds of newly developed analytical assays,the electroanalytical biosensors exhibit numerous advantages,such as good selectivity,high sensitivity,fast analysis speed,low cost,etc.Such assay can also realize the online continuous monitoring in the complex systems.The direct electron transfer between protein and electrode has been extensively studied due to its applications in fields of biosensors,biofuel cells,and bioelectrocatalysis.However,the direct electron tansfer of most redox proteins on bare electrodes is difficult owing to the shielding effect of the protein shell on the redox active sites.Recently,it has been found that nanomaterials with unique structures can promote the direct electron transfer due to their small size and novel physical and chemical properties.According to this kind of thought,a new type of modified electrode based on lipsomal nanomaterial was constructed in this thesis.The corresponding research work is summarized as follow.1.Firstly,ionic liquids based lipid and liposome were synthesized sequentially.Then,ionic liquids based polysome with stable structure was prepared via the the radical polymerization of liposome.Based on the further ionic exchange reaction and the in-situ redution,gold nanopaticles were formed onto the polysome.The surface morphology,structure and properties of the synthetic materials were characterized by DLS,Zeta potential,SEM and TEM techniques.The liposome,polysome and polysome-Au were then combined with horseradish peroxidase to construct modified electrodes and the properties of the enzyme composites were investigated using FT-IR and UV-vis.The results show that polysome-Au not only provide a suitable microenvironment for the immobilized horseradish peroxidase to maintain its inherent structure,but also provide a necessary way for the oxidoreductase to achieve direct electrochemistry.Moreover,they exhibit good electrochemical catalytic properties towards H₂O₂ and NaNO₂.2.Ionic liquids-based polysome and gold nanoparticles were combined to construct polysome/goldnanocomplexes.Nafion/GOD/polysome/GCEand Nafion/GOD/polysome-Au/GCE modified electrodes were also constructed by combining with glucose oxidase.To verify the electrochemical activity of the material,the mechanism of direct electron transfer from Nafion/GOD/polysome-Au/GCE modified electrodes was investigated by cyclic voltammetry and electrochemical impedance spectroscopy.The polysome-Au composite plays an important role in facilitating the exchange of electrons between the electroactive center of glucose oxidase and the electrode,and the immobilised composite membrane retains the bioactivity of glucose oxidase.Furthermore,this modified electrode displayed catalytic activity toward the reaction of glucose oxidation.