Study On Electrochemical Biosensor Based On Metal Nanomaterials And Metal-organic Frameworks

In recent years,nanomaterials have attracted more and more researchers' attention because of its many unique properties,such as small size effects,surface effects,quantum effects,and macro quantum tunneling effects.Based on these characteristics,Nanomaterials have been widely used in the fields of optics,electricity,heat,force,magnetism and chemistry.Among them,nanomaterials show the advantages of large specific surface area,good conductivity,strong adsorption capacity,high electrocatalytic activity and good stability,making it has a lot of applications in the research and development of electrochemical biosensor.Based on the above advantages of nanomaterials,a series of excellent electrochemical biosensors were constructed by using a variety of functional nanomaterials for thrombin?TB?detection.Scanning electron microscope?SEM?,Raman spectra and electrochemical technology are employed to characterize the nanomaterials and the properties of electrochemical biosensors.The detail contents are as follows: Part 1 Synthesis and application of ZnO nanoflowe rs decorated with Pt nanoparticlesIn this work,flower-like Zinc oxide?ZnO?nanomaterials were prepared by the reaction of Zn?NO₃?₂·6H₂O with NaO H,and further immobilized with Pt nanoparticles?PtNPs?.The prepared ZnO nanomaterials with large surface area were employed as carriers to enhance the immobilized amount of other particles.Since PtNPs possess the characteristics of good biocompatibility,high catalytic performance and strong conductivity,it could be applied to immobilize biomolecules,promote the electron transfer and catalyze substrate.Based on the above,ZnO/Pt nanocomposites were prepared and employed in electrochemical biosensors for the further study.PtNPs could can not noly immobilize aptamers and alkaline phosphatase?ALP?,but also could be used as an excellent catalyst.Under the enzyme catalysis of ALP,the electrochemically inactive substrate of 1-naphthyl phosphate?p-NPP?was hydrolyzed to produce electrochemical active 1-naphthol?p-NP?,which was acted as the electron mediator to generate electrochemical signal.At the same time,the PtNPs supported on flower-like ZnO nanomaterials were also applied to catalyze the oxidation of p-NP for signal amplification.The prepared ZnO/Pt nanocomposites exhibit a good effect in electrochemical biosensors.Part 2 Synthesis and application of electroactive Co-based metal-organic frameworksIn this work,Co-based metal-organic frameworks?Co-MOFs?were synthesized by the reaction of Co?NO₃?₂·6H₂O and 2-aminoterephthalic acid?NH₂-BDC?in dimethylformamide?DMF?.After decorated with Pt-Pd bimetallic nanoparticles?PtPd NPs?,Co-MOFs/PtPdNPs could be obtained.Co-MOFs could not only be used as carriers to increase the loading amount,but also as signal labels to generate electrochemical signal without additional introduction of electron media.The introduction of PtPdNPs also focuses on two effects,on is as linker to combine biomolecules based on its good biocompatibility,the other is as an excellent catalyst based on its significant catalytic activity compared with monometallic nanomaterials.Based on the above,Co-MOFs/PtPdNPs had been prepared to apply in electrochemical sensors to the further research.Co-MOFs could provide electrochemical signal and enhance the loading of PtPdNPs.In addition,PtPdNPs could catalize the substrate hydrogen peroxide?H₂O₂?to realize signal amplification,indicating a high sensitivity and stability of the proposed electrochemical biosensors.Part 3 Synthesis and application of metal oxide nanomaterialsIn this work,ZnO nanomaterials and Fe₃O₄ nanomaterials were prepared by hydrothermal method respectively and further modified by gold nanoparticles?AuNPs?to obtain ZnO/Au nanocomposites and Fe₃O₄/Au nanocomposites.Fe₃O₄ nanomaterials possess the unique superparamagnetism,which could be used for the purpose of magnetic separation.ZnO nanomaterials could completely dissolved by adding nitric acid?HNO₃?to transfer into a great amount of Zinc ions(Zn²⁺)to cleave the DNA strand.AuNPs could be employed to combine biomolecules with its good biocompatibility.Based on the above,ZnO/Au nanocomposites and Fe₃O₄/Au nanocomposites were synthesized to construct electrochemical biosensors for further investigation.Through the conversion of ZnO NPs to Zn²⁺,DNA chain immobilized with signal labels could be cleaved greatly,indicating the good sensitivity of the proposed electrochemical biosensor.