Immunosensor Based On Nano-Technology Applied In Biomarkers Detection

Biomarker is a kind of biological protein which is specifically associated with the disease. In clinical detection, it is very important to detect accurately and quickly for patients’treatment in the best time. At the same time, considering the characteristics of biomarkers, it is necessary to develop a highly sensitive detection method immediately. Immunosensing analysis method is a kind of biosensing technology with the combination of the method of immunoassay and sensor technology. It has the qualities of good selectivity, simple, rapid and portability, which has been successfully applied in the detection of the proteins associated with some diseases. In labelled immunoassay, enzymes is one of the most commonly used marker. Although enzymes has good selectivity and high catalytic efficiency, it must work in suitable conditions. Therefore, it is important to search some more stability enzymes.Based on the excellent performance of nanomaterials in chemistry, optics, magnetism and electricity. the introduction of nanomaterials, the development of signal amplification technology and the enhancement of the affinity of the interface and antibody has become the development goals in current chemical sensors.This thesis is carried out under this background, which includes the following several sections:The first chapter, introductionThe first chapter introduces the concept and classification of the biosensor and the labelled immunoassays. At the same time, we discuss the concept and types of immunosensors. Moreover, the application of nanomaterials in immunosensors are emphatically introduced. At the end, the designing idea of this paper is described.The second chapter, the type of enzyme properties of ferritin and its applications in immunosensorsFerritin has horseradish peroxidase-like properties, besides, its enzyme activity is more stable and exhibits a higher thermal stability and resistance to acid and alkali. Based on the widely application of nanomaterials in the aspect of biological senses and the unique advantages of ferritin as signal molecules, this chapter built a double-amplified electrochemical immune detection method. Firstly, we modified glassy carbon electrode with rGO-AuNPs material, and then synthesized AuNPs-Ab2-Ferritin compounds. AuNPs-Ab2-Ferritin/Ag/Abl/rGO-Au-chi/GC sandwich-type immunosensor was constructed. In the optimal condition, the detection of nitrated ceruloplasmin protein (Nitrated CP) was realized. The third chapter, the application of magnetic nanoparticle in immunosensorDue to its unique magnetic properties, biological compatibility and catalytic property, magnetic nanoparticle is become a focus in recent years. In this paper, we modified electrodes with gold nanoparticles to increase electrode surface area. And at the same time, we synthesized Fe3O4/Ferritin-Ab2complexes to amplify the detection signal. In this sandwich-type immunosensor, we took advantage of the high specific surface area and enzyme activity of magnetic nanoparticles.The fourth chapter, the fluorescence quenching properties of gold nanoparticle applied in immunosensorBased on efficient fluorescence quenching of gold nanoparticles and the specifity of antigen and antibody, this experiment established a fluorescence immunity analysis method. At first, we synthesized gold nanoparticle-rhodamine B-Ab2complexes, the fluorescence of rhodamine B was highly quenched In this state. But when adding lysine, rhodamine B molecules leave from gold nanoparticle’s surface and the fluorescence intensity was recovered. The intensity of fluorescence recovery was proportional with the concentration of antigen in the samples, so we can achieve the purpose of antigen determination by measuring the intensity of fluorescence recovery.