Abstract
Surface plasmon resonance (SPR) is a physical phenomenon which occurs in an interface between metal and dielectric materials. A biosensor based on SPR can provide various excellent characteristics such as high sensitivity, rapid examination, label-free pretreatment, and real-time monitor. Thus, an SPR biosensor is often utilized for biodetection and immunochemistry. In this thesis, first we simulated SPR results of two kinds of adhesion layers, titanium and chromium, and measure their experimental SPR results. Both simulations and observations confirm that the SPR curves with titanium display narrower FWHM and lower reflectivity than those with chromium because of smaller internal damping within titanium. Next, we discuss the influence of thicknesses of gold film on SPR. The simulated SPR results of various thicknesses of gold film by Matlab are compared with their experimental data. Our experimental results indicate that a gold layer of 47 nm thick presents the best coupling efficiency to exhibit the deepest reflectance minimum, which is in a good agreement with our numerical simulation. Furthermore, we also observe that the angle shift of the reflectance minimum is highly sensitive to different analytes attached on the surface of the gold film but independent with its thickness. Furthermore, we utilize the aforementioned innovative properties of the SPR biosensor to investigate the binding condition of biomolucules. A couple of high affinity biomolecules, biotin and streptavidin, are adopted to examine the functions of the home-made SPR biosensor. First, the pretreatment of self-assembly is used to immobilize the biotin on the gold film of SPR substrate, and the characteristic absorption peaks of FT-IR of the biotin indicate that indeed the biotin anchors on the gold film. Afterwards, the measurements of various concentrations of streptavidin by home-made SPR system display its high sensitivity; even the 10-8 M of streptavidin can be detected. In addition, we increase the injection rate of streptavidin solution but there is not a significant change because the determining step of kinetic theory is the binding between the biotin and the streptavidin. Currently we are further developing and improving the performance of our SPR biosensors including reduction of cost, miniaturization for portable SPR sensors, and enhancement of the sensitivity for the next generation of SPR systems.