Electrochemical Sensor Based On Pr, W, Dy Nanocomposites

Electrochemical biosensor,as an important branch of biosensor,is a new type of biosensor developed in recent years.In 21th century,the rapid development of nanotechnology provides a rare opportunity for the development of new biosensors.Nanomaterials have excellent physics and chemistry.Carbon materials are widely used in inorganic nonmetallic materials because of their high specific surface area.Because of its high stability and good conductivity,it is widely used in electrochemical biosensors.In this paper,nanocomposites were prepared by hydrothermal synthesis.A new sensor was constructed by introducing rare earth elements and nano-carbon materials to improve the performance of the sensor to a new level.The main research results are as follows:?1?PrFeO₃-MoS₂ nanosheets for use in enhanced electro-oxidative sensing of nitriteThe authors describe the synthesis,characterization and electrochemical sensing performance of a PrFeO₃-MoS₂ nanocomposite.Graphene-like MoS₂ sheets and a perovskite-type PrFeO₃ were synthesized via a hydrothermal and a sol-gel method,respectively.Finally,PrFeO₃-MoS₂ nansheets were synthesized by using sodium molybdate as a source for molybdenum and thiourea as the source for sulfur.The nansheets were characterized by transmission electron microscopy and X-ray diffraction.The electrochemical behavior of the nanosheets deposited on a glassy carbon electrode was studied via electrochemical impedance spectroscopy and cyclic voltammetry.The modified electrodes display strong response to nitrite.At a scan rate of 100 mV·s^-1,the current at the oxidation peak at 0.85 V?vs.SCE?increases linearly in the 0.005 to 3 mmol·L^-1 nitrite concentration range.The detection limit is 1.67?mol·L^-1?S/N=3?.The sensor is selective,stable and reproducible.It was successfully applied to the determination of nitrite in real samples,and appropriate recoveries were obtained.?2?Electrochemical dopamine sensor based on MWCNTs-WO_x NanocompositesMWCNTs-WO_x nanocomposites was fabricated on glassy carbon electrode?GCE?through a simple electrodeposition method,which Tungsten trioxide?WO_x?were fabricated on multi-walled carbon nanotube?MWCNTs?.The morphology and constitution was characterized by field emission scanning electron microscopy?SEM?and X-ray photoelectron spectroscopy?XPS?.Electrochemical characterization of modified electrode was measured by electrochemical impedance spectroscopy?EIS?.The cyclic voltammogram?CV?method was adopted to research the electrochemical behavior of DA on MWCNTs-WO_x modified glassy carbon electrode,and the new Interference detected method of DA was developed by differential pulse voltammetry?DPV?.The results show that MWCNTs-WO_x nanocomposites had obvious electrocatalytic effect on dopamine in pH=6.5 phosphate buffer solution.Under the experimental optimized condition,the DA peak current demonstrated the good linear relationship with the concentration range of 0.05¹.0 mmol·L^-1,the detection limit was 16.67?mol·L^-1.Simultaneously,the effect of different experimental parameters on the response current of the modified electrode were investigated,it was found that the prepared electrochemical sensor displayed a good reproducibility,high selectivity and strong anti-interference ability.In the presence of UA,a new electrochemical method for the quantitative determination of DA was established and successfully applied to the determination of dopamine hydrochloride injection in real samples.?3?H₂O₂ biosensor based on GO-Dy₂O₃/Hb CompositesThe nanocrystalline dysprosium oxide Dy₂O₃ was prepared by hydrothermal method.GO was prepared by modified Hummers method.The nanocomposites of GO,Dy₂O₃ and hemoglobin?Hb?were decorated on the surface of the bare glassy carbon electrode?GCE?to construct the biosensor for th detection of H₂O₂.The morphology of the modified electrode was characterized by field emission scanning electron microscope?SEM?and X-ray diffraction?XRD?.The Electrochemical behavior was analyzed by cyclic voltammetry?CV?and electrochemical impedance spectroscopy?EIS?.Owing to the good conductivity and biocompatibility of GO-Dy₂O₃,the GO-Dy₂O₃/Hb modified electrode exhibited good electrochemical catalytic effect towards the reduction of H₂O₂,and.The direct electron transfer between Hb and working electrode was promoted by the nanocomposite.the effects of different pH values and electrochemical scan rates on the response current of the modified electrode were studied.The biosensor showed a good linear relationship with H₂O₂ in the range of 60³00?mol·L^-1,and the correlation coefficient was R²=0.996.The detection limit of the biosensor is 20?mol·L^-1?S/N=3?.This biosensor has the advantages of wide detection range,good stability and reproducibility,strong anti-interference ability,and could be used for the detection of real samples.