The Synthesis And Modification Of Au/Fe₃O₄ Magnetic Nanoparticles And Its Application In Biological Detection Of C-reactive Protein

The Au/Fe3O4 nanoparticles with monodispersity and high saturation magnetization have become one of hotspots because their important and wide application in drug targeting,cell and protein separation,immune detection and even the catalysis.In this thesis,Au/Fe3O4 nanoparticles with uniform size,high saturation magnetization and stable dispersion in the oil phase was prepared by high temperature pyrolysis method.The phase transfer of Au/Fe3O4 nanoparticles were achieved by oxidizing the oleic acid on the nanoparticle surface to a hydrophilic carboxyl group.After Au/Fe3O4 nanoparticles were modified by PAA,the nanoparticles were applied as nanocarrier in chemLuminescence immunoassay(CLIA)for the detection of C-reaction protein based on luminol-H2O2 system,the detail results were obtained as follows:(1)Preparation of Au/Fe3O4 magnetic nanoparticlesUsing Au NPs as seeds,Fe(CO)5,oleic acid(OA)as reactants,1-octadecene as solvent,Au/Fe3O4 NPs were prepared by adjusting the ratio of reactants.Then the Au/Fe3O4 particles were characteried by VSM,TEM,UV-vis,XRD,FT-IR.The nanocrystals of Au/Fe3O4 are flower-like,narrow in size distribution with diameter of 35nm.FT-IR and TGA datas show that the surface of the nanoparticles adsorbed by oleic acid molecules,and the mass ratio of is 22.3%.The magnetic NPs adsorbed with oleic acid molecules have good dispersibility in the cyclohexane.The NPs exhibit superparamagnetic at room temperature,and the maximum saturation magnetization is 37 emu/g.(2)The phase transfer and polyacrylic acid(PAA)modification of Au/Fe3O4 nanoparticlesThe phase transfer of Au/Fe3O4 NPs were carried out by oxidation of oleic acid based on sodium periodate as the oxidant and modified with PAA.Then the Au/Fe3O4 NPs were characterized by various analytical methods.The characterizations of phase transferred and PAA modified Au/Fe3O4 NPs indicate that the morphology and size as well as the crystallinity of Au/Fe3O4 NPs do not have any obvious change.The maximum saturation magnetization of Au/Fe3O4 magnetic nanoparticles at room temperature was 36 emu/g after PAA modification.The stability of PAA-Au/Fe3O4 magnetic NPs showed that the composite particles had good dispersibility and can be stable for 4 months in the aqueous solution.(3)The detection of CRP based on CLIA by employing PAA-Au/Fe3O4 nanoparticles as nanocarrierPAA-Au/Fe3O4 were employed as nanocarrier for the development of a highly sensitive C-reactive protein(CRP)chemiluminescence immunoassay(CLIA).In addition,zwitterionic glycerophosphoryl choline(GPC)was employed as a co-blocking agent to reduce the nonspecific absorption.After the sandwich immunocomplexes were formed with the addition of the human CRP antigen and anti-CRP-HRP,the chemiluminescence were detected based on horseradish peroxidase(HRP)-luminol-H2O2 system.The calibration curve displays good linearity in the range of 1-250 ng/mL.LOD was calculated to be 0.26 ng/mL(2.5 pM),which is quite sufficient for the clinical diagnosis of arteriosclerosis.Hence,the successful detection of CRP in clinical samples in CLIA system was demonstrated with effectiveness that surpass conventional assays.