| Silica and Janus micro/nanoparticles have the advantages of small size,special structure,large surface area,and easy surface functionalization.Therefore,Janus and silica micro/nanoparticles can be used as materials for electrode surface modification in the field of electrochemical sensing analysis.This paper is based on surface functionalized Janus and silica micro/nanoparticles,which are used as electrode surface modification material to construct electrochemical sensors for ractopamine（RAC）,ochratoxin A（OTA）and xanthine（HX）detection analysis.Chapter 1: The concept of micro/nanoparticles is briefly introduced,and the synthesis and application of silica and Janus micro/nanoparticles are summarized.A brief introduction to the research and application of silica and Janus micro/nanoparticles in the field of electrochemical sensing.Chapter 2: The aptamer/octadecanethiol Janus particles electrochemical sensor was constructed for the detection of ractopamine.The treated glassy carbon electrode is hydrophobic and can interact with the hydrophobic group octadecyl mercaptan on the Janus particles to make the Janus particles more firmly modified on the surface of the glassy carbon electrode.At the same time,the other side of the Janus particle has amino groups,which can fixing Au nanoparticles to the other side of the Janus particle,and then attaching the aptamer to the surface of the Au nanoparticles through Au-S bond,thereby firmly bonding to the electrode surface.The surface of the electrode was characterized by cyclic voltammetry（CV）,alternating current impedance（EIS）and scanning electron microscopy（SEM）.Concentrations range of RAC were detected by differential pulse voltammetry（DPV）.The detection range is 1.0×10-13 1.0×10-11 M and 1.0×10-11 1.0×10-7 M with linear coefficients of 3.3×10-14 M,respectively.This work is designed to synthesize new Janus microparticles,which may provide a new method for electrochemical sensing detection of Janus particles.Chapter 3: Construction of electrochemical sensor based onaptamer/NH2 Janus particles for the detection of ochratoxin A.A layer of Au was evaporated on the hemisphere of the amino polystyrene microspheres by vacuum evaporation apparatus,and then the thiolated OTA aptamer was modified on the surface of the Au layer by Au-S to prepare aptamer/NH2 Janus particles.The carboxylated graphene（COOH-GN）was fixed on the surface of the glassy carbon electrode by physical adsorption,and the Janus particles were fixed on the surface of COOH-GN by amide bond.The surface of the electrode was characterized by CV,EIS and SEM;Concentrations range of OTA were detected by DPV.The detection range is from 1×10-5 n M to 10 n M with detection limit of 3.3×10-3 p M.The sensor can be directly used for OTA detection in red wine samples.This work takes advantage of the unique structural advantages of Janus particles and may provide provide new ideas for constructing electrochemical sensors for detecting OTA.Chapter 4: Construction of ratio electrochemical sensor based on silica particles functionalized with 5-Ferrocenylisophthalic acid（FPA@SiO2）for the detection of xanthine.A novel 5-Ferrocenylisophthalic acid material is synthesized and functionalized with silica particles.The composite materials were characterized by UV-vis absorption spectroscopy（UV-vis）,nuclear magnetic resonance（NMR）,transmission electron microscopy（TEM）and scanning electron microscopy（SEM）.The diameter of FPA@SiO2 is between150 and 200 nm.Then,FPA@SiO2 were composited with graphene materials and characterized by electrochemical,which was found have good electrical conductivity.Silica nanoparticles serve as an excellent carrier for binding more 5-Ferrocenylisophthalic acid because of the large surface area.The detection range is from 0 μM to 180 μM.This method may eliminate the interference caused by the amount of material on the surface of the electrode,and provides a new idea for the construction of the ratio type electrochemical sensors. |
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