Symmetrical Structure Based Long-range Surface Plasmon Resonance Sensing And Its Application

Surface plasmon resonance (SPR) is a label-free and highly-sensitive sensingtechnique, which has been widely used in biosensing, food safety, medical and otherfields. Recent years, with the continuous development of the biotechnology, people putforward higher requirements to detection technology. As a result, the long-range SPR(LRSPR), as its higher performance, has attracted more and more attention.In this thesis, after analysis of the conventional SPR and LRSPR theory, weproposed a new symmetrical structure LRSPR based on MgF2-Au-MgF2film. Based onthe multilayer reflective theory, we calculated the resonance curves, electric fieldenhancement and dynamic range of high properties of LRSPR. All of those are greatlyimproved in comparison with conventional SPR and normal LRSPR. What’s more, weobtained the best matching film thicknesses and the varying regularity of the resonancecurves with the film thicknesses, which provide theoretical guidance for the experiments.Through long-term exploration and debugging, we mastered the technology of theexcellent film prepared to meet the experimental needs.Then, we designed and assemble the sensing system based on angle detection, anddetermined the sensitivity and the refractive index resolution of the system in liquid andatmosphere environment. In the liquid environment, we used sodium chloride solutionas the analyte, the sensitivity of5.5105pixels/RIU and refractive index resolution of8.110-8RIU was required. In the atmosphere environment, we used air as the analyte,the sensitivity of2.3105pixels/RIU and refractive index resolution of3.710-7RIUwas required. Those are better than the conventional SPR and the normal LRSPR,which also fully affirmed the significance of this symmetrical structure based onMgF2-Au-MgF2.Due to the sensing layer of new LRSPR is magnesium fluoride, the surfacebiological modification method based on metal of conventional SPR and normalLRSPR is no longer applicable. We applied dopamine to modifying magnesium fluoridefilm surface, so that the surface can be activated for further binding reaction. As a result,the new structure can be applied to biosensing. After that, we applied this symmetricalstructure LRSPR sensing system to detection of E. coli and cytokines in human aqueous humor. Outstanding results were required, which proved that our system can be appliedto biosensing with superior performance.This symmetrical structure LRSPR biosensing system came out of our deepthinking of LRSPR theory, so the optimizing for sensing characteristics from thecharacteristics of the structure itself. Therefore, this method will undoubtedly bring newpossibilities to promote the development of SPR technology.