The Application Research Based On The Enzyme Induced Growth Of Metal Nanoparticles

Immunosensors could combine the high specificity of immunoreaction and high sensitivity of sensor technology.It's one kinds of novel biosensors.It has widely application due to its sensitive,low time consume and low detection capability.Howerver,when the nanotechnology was introduced into the immunosenosrs area,it can improve the detection property.Nobel metal nanoparticles has been widely applied in novel immunosensors research result from its remarkable photophysical and photochemical properties,such as fluorescence,electroconductivity,localized Surface Plasmon Resonance(LSPR),oxidation-reduction property and surface modification.Combined with organic molecules or biomolecules,Metal nanoparticles can be used for the small and high molecular compound detection.The application of metal nanoparticles in immunosensors mainly depended on the particles size,shape and uniformity.Thus,the research for noble metal nanoparticles with uniformity and high stability is still a focus.This dissertation is divided into four parts.The first chapter is an overview on the recent research of the synthesis of metal nanoparticles and immunosensors based on gold nanopartilces,including follow:1)Synthesis methods for AuNPs,AgNPs and Au@AgNPs(core-shell).2)Nanoparticles growth induced by the enzyme.3)immunosensors.4)Purpose and content of the dissertation.In chapter 2,we proposed a simple,rapid and economic method to synthetise uniform and stable AuNPs,AgNPs and Au@AgNPs(core-shell).This method mainly uses the enzyme to catalyze the substrates to reducing products to reduce HAuCl4 and silver ammonia solutions complex to gold and silver which were coated on the metal nanoparticles seeds surface,resulting to the growth of metal nanoparticles seeds.With this method,it can synthetise different sizes and uniform AuNPs,AgNPs and Au@AgNPs(core-shell).In the chapter 3,a novel immunosensors were prepared on the basis of the synthesis principle reformed from chapter 2.The antibody which was modified with glucose oxidase was linked to the gold nanoparticle which was on the glass surface.Glucose oxidase would catalyze the glucose to hydrogen peroxide which has strong reducing property.Thus it would reduce HAuCl4 to gold,coating on the gold nanoparticles seeds surface and making the seeds grow.The growth of gold nanoparticle seeds lead to the remarkable increasing of absorbancy.According to the proportion of absorbancy increasing and antigen concentration,we can detection the Neuron-specific enolase(NSE).This method not only has high sensitivity,selectivity and reproducibility,it is aIso easy operation.Its detection line is low to 1×10-18g/mL.In the chapter 4,the stable gold nanoparticles was modified with glucose oxidase in the solution.And combined with the magnetic bead(MB)separation technology,It can realize the high sensitive detection for the tumor marker alpha fetoprotein(AFP)in the sample.The result showed this method not only has high sensitivity,selectivity and reproductivity,but also has the advantages of easy operation and simple equipments.With this method,the detection would low to 1 × 10-12 g/mL.