Preparation Of Sialic Acid Mips Nano-Materials And Electrochemical Biomimetic Sensors Based On MIT And EATRP

Molecularly imprinted polymers（MIPs）synthesized by the molecular imprinting technique can not only specifically identify target molecules.It also makes up for the shortcomings of high cost and environmental sensitivity in biometrics,and is a preferred material used in the field of analysis and identification.In particular,nano-MIPs materials have a high specific surface area,which greatly increases the effective recognition sites of materials and reduces the slow binding rate caused by the embedding of recognition sites.In order to obtain excellent performance of MIPs,it is very important to control the stent-molecule-oriented cross-linking polymerization process.Electrochemical mediated atom transfer radical polymerization（ATRP）applied electrochemical techniques to common atom transfer radical polymerization（ATRP）and introduced a new strategy to dynamically control the REDOX mediated radical polymerization process.It not only solves the problem of large amount of common ATRP catalyst,but also improves the control of the polymerization process and the oxygen tolerance of the system through physical adjustment.It is a precise,controllable,convenient and environmentally friendly polymerization method.In this work,MIT and eATRP technologies are combined to control the synthesis of MIP in a convenient and controllable way.Firstly,MIPs nano-sphere was prepared for specific recognition of sialic acid（SA）molecules.On this basis,a layer of MIPs molecular recognition film was modified on the gold electrode by using the surface induced eATRP（SI-eATRP）technology.A modified electrode electrochemical sensor with specific detection ability for SA was prepared by using it as recognition element.The specific work is as follows:1.Preparation of molecularly imprinted nanospheres by electrochemically mediated atom transfer radical precipitation polymerizationUsing SA as template molecule and 4-vinyl phenylboric acid（4-VPBA）as functional monomer,MIP microspheres were prepared by eATRP and precipitation polymerization in the presence of crosslinking agent ethylene glycol dimethacrylate（EGDMA）.In this work,the effect of potential regulation on the structure,morphology and size of MIPs microspheres was studied,and the recognition performance of MIPs on SA molecule was studied.Among them,the characteristic groups in Fourier transform infrared spectroscopy（FTIR）proved the successful synthesis of MIPs.Scanning electron microscope（SEM）images show that the particle size of spherical MIPs is at nanometer scale,and the particle size is uniform.By comparing the morphology of different polymerization potentials,it can be found that the polymerization potential can change the morphology and size of polymer microspheres.Finally,the binding properties of imprinted nano-spheres were studied,including binding kinetics and thermodynamic isothermal adsorption.The results showed that the adsorption behavior of SA by MIPs was more consistent with Freundlich isothermal adsorption model and pseudo-second-order kinetic adsorption model.The selective binding experiment also proved that MIPs had a good specific adsorption capacity for sialic acid,indicating that the spatial recognition sites complementing SA in shape,size and functional groups were prepared under the regulation of eATRP.2.MIPs ultra-thin film modified electrode synthesized by SI-eATRP to prepare a novel electrochemical sensing platform for specific detection of sialic acidThe bromine initiator was anchored to the surface of the gold electrode,SA was used as template molecule and 4-VPBA was used as functional monomer.In the presence of crosslinking agent EGDMA,SI-eATRP technology was used to prepare SA molecularly imprinted polymer ultrathin film on the surface of the gold electrode,and the electrochemical impedance sensor was used as the recognition element of the sensor to prepare the ultra-sensitive detection of SA.X-ray photoelectron spectroscopy（XPS）was used to characterize the characteristic elements of the polymer film,which proved the successful modification of MIPs film.Electrochemical impedance（EIS）was used to characterize the layer modification process of the electrode indirectly.For obtain the thickness of polymer film,the ellipsometry was carried out,and the thickness of MIPs film was 5.742±0.158nm,which is nano-scale ultra-thin film.The morphology of MIPs films was characterized by atomic force microscopy（AFM）and scanning electron microscopy（SEM）,which proved the successful modification and uniform growth of MIP films.Finally,EIS was used to test the detection performance of MIPs modified electrode sensor,and it had a good linear response to sialic acid in the range of 1.0×10^-12～1.0×10^-9 g/m L.The linear regression equation is as follows:R_ct（k?）=–391.08+999.07lg C,correlation coefficient R²=0.9915,and limit of detection（LOD）was 0.52×10^-12g/m L（S/N=3）.The results show that the electrochemical sensor has excellent specificity for sialic acid detection.