Preparation Of The Novel Composite Gold Magnetic Nanoparticles And Their Application In The Dection Of Major Zoonotic Diseasea

Gold magnetic nanoparticles with core-shell structure have attracted extensive attention in the field of disease diagnosis because of their unique magnetic properties and excellent biocompatibility.Gold magnetic nanoparticle,which is usually used as ideal carrier for disease diagnosis,must have the following characteristics:1)high saturation magnetization;2)good dispersion and stability of nanoparticles;3)good antifouling ability on the surface of nanoparticles against nonspecific protein adsorption.Currently,under the premise of supermagnetic magnetic nanoparticles,high hydrophilic materials were used to modify the gold magnetic nanomaterial interface through the appropriate chemical modification to improve the hydrophilicity and the antifouling ability of the nanoparticle interface in a complex biological system.Then,to achieve the highly sensitive and selective performance of magnetic nanoprobes in the application of disease detection,the nanoparticles were immobilized with a highly specific target protein or DNA.In this paper,different structures of hydrophilic materials were modified on the surface of Fe₃O₄@Au nanoparticles which were prepared through nanoparticle synthesis technology and nanoparticle surface modification technology.Then,different target proteins or DNA were selected to immobilize on the surface to detect disease.The gold-immunomagnetic probes based on gold magnetic particles were constructed and applied to the detection of brucellosis or HPV DNA in 100%serum by electrochemical sensors.This article consists of the following three aspects.1)Preparation and predispersion of gold magnetic nanoparticles.Co-precipitation method was used to synthesize superparamagnetic magnetic nanoparticles with particle size of about 7-10 nm.Then,the Fe₃O₄@Au nanoparticle with core-shell structure was synthesized by chemical in-situ reduction method.The amine-terminated poly?ethylene glycol?was modified on the surface of Fe₃O₄@Au nanoparticles to achieve high dispersion and excellent antifouling properties through Au-N bonds.Then,the dispersibilityofFe₃O₄@Au@PEGnanoparticleswasstudiedbyUV-Vis spectrophotometer and the anti-fouling properties of the prepared gold magnetic particles were studied by electrochemical differential pulse voltammetry.Interestingly,the experimental results show that Fe₃O₄@Au@PEG nanoparticles can maintain good dispersion at pH values of 3.0,10.56,and 12 as well as salt ion concentration?10 m M,20mM,50 mM?.In addition,the prepared gold magnetic nanoparticles are stable when the temperature ranges from-20°C to 95°C.However,protein-resistant performance of Fe₃O₄@Au@Au@PEG nanoparticles in 100%serum remains to be further improved.2)A novel Fe₃O₄@Au@PEG@CSA nanoparticle was synthesized based on Fe₃O₄@Au@PEG NPs.And the Fe₃O₄@Au@PEG@CSA nanoparticle was used in the construction of gold magnetic immunosensors to detect disease markers by fluorescence immunoassay or electrochemistry.In this paper,a novel magnetic nanoparticle was successfully prepared by covalently grafting chondroitin sulfate?CSA?molecules onto amino-terminated Fe₃O₄@Au@PEG nanoparticles.The experimental results show that CSA-coated Fe₃O₄@Au@PEG nanoparticles?CSA-coated Fe₃O₄@Au@PEG?exhibit excellent stability,biocompatibility,especially non-contaminating properties which make up for only one layer of PEG-modified.Due to the synergy of PEG and CSA on the surface of Fe₃O₄@Au nanoparticles,the rate of change of the DPV response of the Fe₃O₄@Au@PEG@CSA modified electrode was as low as 1.61%before and after the100%serum incubation.More importantly,it could be successfully applied in rapid,direct diagnosis of disease markers in 100%serum.All these results show that this novel nanomaterial can be used for a wide range of detection areas and shows very excellent specificity recognition in buffer even in the whole serum.3)A new type of electrochemical immunosensor for brucellosis was constructed based on hyaluronic acid-coated Fe₃O₄@Au@PEG nanoparticles which were synthesized based on Fe₃O₄@Au@PEG NPs and characterized by TEM,SEM,XRD,FTIR and EDS.The experimental results show that HA-coated MNPs-modified immunosensors exhibit high selectivity,sensitivity and almost perfect antifouling properties in various external environments,especially in complex biological systems.More importantly,this immunosensor is capable of measuring the target antibody in 100%serum without any significant interference.In addition,the linear range of detection of the target antibody by the immunosensor is 10^-1515 g mL^-11 to 10^-1111 g mL^-1,and the detection limit?LOD?is 0.316fg m L^-1.All the results show that this kind of immunosensor has great potential in clinical diagnosis.