Nano-bio Dielectric Characteristics And Immuno-electron Detection

Nano Technology,as the rising technology in the end of 20 century,extends its research to a lot fields. Nano-biosensing is the most exciting cross subject,including nano-biology,nano-electronics and nano-materials. Nanogold is the one of the most important research content in nano-biosensing technique.Nanogold,as one of immuno-labeling technique,is achieving very fast development. The intrinsic electronic characteristic of nanogold has highly attracted attention,especially for application of immunosensing. However,the related research lacks comparing with other methods. Here the electronic characterization of nanogold-antigen-antibody-complex was introduced,for realization of quick,sensitive,and simple immuno-sensing.The immunosensing based on antibody plays an important role in clinical diagnosis,food industry,molecular biology and so on. However,the dielectric property displays so small variation in antibody-antigen binding assay that it is difficult to biosensing using electronic methods. For example,antibody-antigen complex displays the gigantic impendance and the small variation in the antibody-antigen binding procedure. All these difficulties limit the development of electronic detection method for immunosensing.To overcome these disfficulties,this thesis adopted nanogold-antigen-antibody complex as the investigated subject. The nano-bio-semiconductor effect was discussed based on the doped nanogold. The dielectric properties and characterization technique of this complex was investigated. Then these methods were applied to immnunosensing. In this paper,two kinds of research were carried out to characterize nanogold-antigen-antibody-complex after preparation of nanogold protein probe. Firstly,the AC conductivity of this complex was detected on the porus film,and optimizing factor was investigated,such as electrode,frequence,doped ions. Secondly,the capacitance of double layer was detected to characterize the modified working electrode by this complex that represents the binding of antigen and antibody. For first resolution,cellulose film was adopted as substrate to immobilize thenanogold-antigen-antibody-complex. The conductivity was detected and analyzed using novel double-ring electrode. The results revealed high sensitivity for antigen detection based on conductivity. For second resolution,gold disk electrode was modified using Self-Assembly-Membrane technique,and then complex was immobilized using terminal groups. The relation between density of complex and capacitance of double layer was detected using small-amplitude-triangle wave. The results revealed that sensitivity was improved comparing with free-labeling capacitance biosensor. These researches displays that high electronic sensitivity based on nanogold complex has potential possibility to realize free PCR and single molecule biosensing.In these experiments,the most important factor is control of nanogold bio-assembly. Atomic Force Microscope was adopted to analyze the spectrum of binding force,to optimize the binding condition.For valid analysis of experiment and correct understanding of electronic properties of nanogold complex,modeling was done. It included:the mesophysics mechanism of nanogold thin film,the devotion for double layer and the relation between nangold complex and binding reaction. The analysis revealed that the binding reaction affected the volume percentage,which determined the conductivity and double layer.At last,a design based on complex is introduced to detect the multi hepatitis for displaying value and feasibility of this method.