Research On Biochemical Sensing Of SPR Chip And Fiber-Optic SPR Sensing Technique

For great advantages of high sensitivity, high accuracy, label-free, non-destructive and real-time detection, the surface plasmon resonance (SPR) sensing technology has been widely used in the areas of biosensing, drug discovery, clinical diagnosis, environmental monitoring, and food analysis and so on, which becomes a very active topics in sensing area. In this dissertation, prism-coupled SPR sensor with Au/Ag bimetallic film, Fiber-optic SPR sensor with dielectric film of MgF2, crescent-coated Ag film and D-type Fiber-optic SPR sensor are studied both in theory and experiment.The main research works and conclusions in this dissertation are as following:1. The prism-coupled SPR sensor is simulated by transfer matrix method. The SPR characteristics of different metal film are compared and discussed. The Ag film has a narrow SPR curve and poor chemical stability while the Au film has a good characteristic in chemical stability and biological modification. A bimetallic film with Au/Ag film is proposed and optimized which can combine the advantages of silver and gold. The SPR sensor with bimetallic film of10nm Au film and40nm Ag film shows the best sensing performance. After that, a double-measure-angle intensity interrogation method with simple detection device and algorism is proposed, which both can eliminate the light intensity fluctuation and improve the sensitivity of the sensor.2. The Au/Ag bimetallic film is prepared and employed in the commercial surface plasmon resonance (SPR) instrument, Biacore3000for biological test. The bimetallic film shows a sharper resonant curve than common Au film which can improve the sensing accuracy. After that, the bimetallic sensor chip is tested by detection of sulfamethoxazole (SMX) and estradiol (E2C) using competitive inhibition method. The experiment result shows that the bimetallic sensor chip can work stably and regenerate repeatedly. The limit of detection (LOD) of SMX and E2C are decreased to1.78ng/ml and0.31ng/ml. Then, SMX concentrations in ten commercial milk samples are determined. Double-measure-angle intensity interrogation method is tested by detection of E2C, which have a LOD of0.30ng/ml, the same as traditional method. 3. Fiber-optic SPR sensor with uniform-coated silver film and MgF2dielectric film is studied theoretically and experimentally. The sensor with different structure parameters is investigated, like the numerical aperture (NA), diameter of fiber core, length of the sensing region and refractive index (RI) of the environment, which shows that the sensitivity of the sensor is increased monotonously with the environment RI. The sensitivity can reach5.3*103nm/RIU at the RI of1.3945. An MgF2coated fiber-optic sensor with uniform-coated silver film is designed and fabricated, which has the advantages of stable, high sensitivity and low cost. Different dielectric film and thickness are discussed and optimized. The result shows that the sensor with10nm MgF2has the best sensing performance which can reach the sensitivity of4.8*103nm/RIU at environment RI of1.3945.4. To simplify the preparation process of uniform-coated fiber-optic SPR sensor, a fiber-optic SPR sensor with crescent-coated Ag film is fabricated and studied by one-side coating. The sensor with different Ag film is tested, which shows that the optimized thickness of the sensor is40nm. The sensitivity of the sensor can reach4.8*103nm/RIU at environment RI of1.3901, nearly the same as the uniform-coated sensor. By control the polariton of incident light and length of sensing region, a double-channel fiber optical sensor is proposed and realized based on sensing region with different silver thicknesses of20nm and50nm. At last, D-type fiber-optic SPR sensor is tested which have a sensitivity of4.4*103nm/RIU at RI of13998.Highlights of the dissertation are as follows:1. An Au/Ag bimetallic film is designed and employed in Biacore3000system for the first time, which shows a higher sensing accuracy and lower LOD than common Au film. A double-measure-angle intensity interrogation method is proposed and tested for biological detection. The result is significant to improve the detection accuracy and sensitivity of commercial SPR instrument.2. An MgF2coated fiber-optic sensor with uniform-coated silver film with advantages of stable, low cost and high sensitivity is studied. It has a sensitivity of4.8*103nm/RIU at RI of1.3945, which higher than Au and Au/Ag coated fiber-optic sensor. A fiber-optic sensor with crescent-coated Ag film is proposed and fabricated, at RI of1.3945, the sensitivity can reach4.8*103nm/RIU at RI of1.3901, nearly the same as the uniform-coated sensor. 3. A double-channel fiber-optic sensor base on different Ag thickness is studied. By control the polariton of incident light and length of sensing region, the double-channel sensor with Ag thickness of20nm and50nm is realized which shows a good sensing performance.