| Biosensor is a multidisciplinary platform which includes physics, chemistry, biology, microelectronics and mechanics. The biosensor will generate signals when the sensing elements interact with samples. It can be qualitatively and quantificationally analyzed the samples through signal processing, which includes amplification, reception, transformation, filtering and output. Comparing with the traditional detection methods, the biosensor has enormous advantages of high precision, fast response and low cost. Hence, it has extensive application in the medical diagnosis, environment monitoring and food hygiene. In these applications, the sensor surface can be functionalized by biochemical substances which were used to detecting the virus, antibodies, antigens and other hazardous substances. The accuracy of detection is relevant to the quality of the surface functionalization.In recent years, the requirements of biosensors is higher with the situation of livehood security frequently happened such as Ebola virus, SARS virus and H1N1 avian influenza virus. The traditional biochemical detection methods for these viruses are usually needed a few days, weeks, or even longer to get results. Besides, it will need more time to prepare the vaccines of virus. Hence, how to provide a platform with the detection of real time and accuracy have become the urgent problems in the worldwide. In recent years, the biosensors enter a new period of miniaturization, portable and intelligent with the development of technology of electronics and micro-electromechanical systems. Based on the improvements, it is laying a good foundation for solving the above problems. At present, the piezoelectric biosensors and surface plasmon resonance biosensors have become the focus under the study because of the high sensitivity and the excellent signal response. For example, the sensitivity of the quartz crystal microbalance and surface plasmon resonance are the level of nanogram and pictogram, respectively. Hence, it can be satisfied the requirements of detecting virus, environments and food, meantime, it also can be promoted the industrial progress for the biosensors through carrying out the investigation of the quality and efficiency of surface functionalization.In this paper, the influence factors of surface modification were studied. Based on these results, it was provided a method of detection and the theoretical supporting by combined with bond-rupture technique, molecular dynamic principle, Maxwell electromagnetic wave propagation equation and finite element method. The research contents were included with four parts:1. The effects of temperature and time on immobilization were studied by using bond-rupture biosensor and Monte-Carlo algorithm. The best temperature and time for immobilization were 60? and 2 hours, respectively.2. The effect of mixed thiol on the efficient of immobilized immune globulin G was studied. It can be got the best surface structure and immobilized the most IgG when the molar ratio between 16-Mercaptohexadecanoic acid and 11-Mercapto-1-undecanol was 1:7. In this structure, the tilt angle, thickness of monolayer and emerge of adsorption were 29°,21.765A, and-182.42KJ/mol, respectively. In the experimental results, the shift of resonant frequency was 243Hz when the molar ratio was 1:7. Hence, the theory model was verified by the experiment. The protein A and Protein G were immobilized on the QCM which was modified with IgG. The shift of resonant frequency was 464Hz for protein A and 870Hz for protein G. The specific bond of voltage for protein G was 2V and the non-specific bond of voltage for protein A was 0.5V. These results were established a foundation for the application of medical diagnosis, environment monitoring and food hygiene.3. Two SPR theory models were proposed by Fresnel's formula and finite element analysis method, respectively. According to the simulation results, the FEM model was more accuracy and the relative error of resonant angle between theory and experiment was 0.1°. This result was provided a new theory platform for characterizing the process of Electromagnetic wave propagation.4. A 3D-SPR model was proposed based on the 2D model. The effect of molar ratio of mixed thiol on resonant angle was studied. The relative errors of resonant angle between simulation and experiments were -0.3°,-0.3°,0.1°nd 0° when the molar ratio were 1:1,1:3, 1:5 and 1:7, respectively. The reason was that the surface structure of mixed thiol would influence the roughness of surface which makes the resonant angle shift.5. The relation betwenn wavelength and loss factor of electromagnetic wave were investigated. Baesd on these results, the effect of structure of carbon nanotubes on propagation loss and absorptivity of electromagnetic wave were studied. It was got that the achiral single-walled carbon nanotube with structure of (9,0) was in favor of propagation for electromagnetic wave.The best diameter of carbon nanotube bundle was 116nm and the absorption power was 1.42x 10-6w when the wavelength was 632.80nm. Hence, it was not merely expanded the study of SPR from small molecules to macromolecules, but also established the foundation for detecting biomolecules.In conclusion, the surface functionalization was investigated in the both biosensors and two new theory models were established. All these research were provided theoretical support for improving the quality of functional surface. In addition, it established a foundation for the application of medical diagnosis, environment monitoring and food hygiene through detecting and identifying the immune substances and organic molecules. |
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