Detection Of Heavy Metal Ions Based On Surface Plasmon Resonance

Surface plasmon resonance (SPR) sensing technique has become a powerful analytical tool since thirty years ago, which finds a wide and potential application in the field of biological and chemical detection for its several distinctive features, such as non-destructive, high sensitivity and resolution, no necessity of reference solution, purification of the object to be measured, label-free measurement and real time analysis. In this dissertation, we combined SPR sensor with surface modification of sensor chip and then studied its application in the detection of heavy metal ions.This dissertation expatiated the mechanism and excitation condition of SPR systematically, analyzed the attenuated total reflection prism coupling geometries and discussed reflectivity of multilayer structure. A home-built apparatus of SPR based on Kretschmann model was introduced.The content of experiment includes preparation and modification of sensor chip, detection of heavy metal ions using modified sensor chip.The gold film of sensor chip was prepared by magnetron sputtering and its thickness is set to50nm according to the result of theoretical simulation. In order to modify the surface property of the sensor chip, a self-assembled monolayer(SAM) of1.6-hexanedithiol(HDT) was established. The morphology of modified surface was investigated by Atomic Force Microscope (AFM) and compared with the results of non-modified surface. The SPR angle shift by self-assembled layer of HDT was studied and compared with the simulation data. The time of SAM formation was also discussed.We measured the SPR angle shift of the sensor chip before and after Hg2+adsorption on HDT SAM. To study the selective adsorption properties of sensor chip with HDT, we detected the solution of single heavy metal ions and mixed heavy metal ions by in-situ intensity modulation sensing. The influence of solution concentration to the results is investigated and we obtained the limit of the detection of solution concentration. We also measured different concentrations of Hg2+solution with HDT modified and unmodified sensor chips and researched their detection sensitivity to Hg2+by contrast in angle modulation mode.