| Surface plasmon polaritons(SPPs)are surface electromagnetic waves induced by charge-density oscillations which exist at the metal/dielectric interface.SPPs around the metal surface can greatly enhance the light transmission and redistribute the electromagnetic field at the nanoscale dimension.These properties provide us with a new technical solution for breaking the optical diffraction limit,and also facilitate a series of technology advancements in the areas of micro-nano science,integrated optics,and optical methodology,etc.With the rapid development of micro-nano manufacturing technology,the techniques regarding optical measurement.metrology,and controlling on the metal surface based on SPP theory are quickly penetrating into other related fields,such as biochemistry,nanophotonics.optoelectronics,and so on.Surface plasmon resonance(SPR)sensing technology has been widely used in biochemical analysis,such as antibody selection,disease control and prevention.and drug screening,because of their superior advantages including high sensitivity and resolution,real-time monitoring capability,label-free detection and non-purification request.In recent years,SPR has been developed as one of the most potential biochemical sensing solutions due to the rapid development of sensing theory and technolog,y based on micro-nano-structure SPP.This thesis mainly focuses on the design and development of optical SPP biochemical sensing technologies based on micro-nano mechanism and their applications.Based on the fundamental principle of SPP.we construct and analyze the theoretical models of micro-nano sensing structures,and then design,fabricate and demonstrate some novel micro-nano SPP sensors.In order to enhance the sensitivity and stability of these micro-nano structure SPP sensors for using in practical biochemical sensing applications,we analyze the influences of-metal material characteristics,structure and assembly method of the micro-nano metal layer on the sensing performances,and realize the specific chemical binding activities monitoring of the biological molecules in the lab-scale experiments.providing solid theoretical and experimental foundations for developing SPP biomedical sensing technology with high sensitivity,diversity and universality.Major research works in the thesis are summarized as follows.1.Based on SPP theory,we study the sensing mechanism of micro-nano-structure SPR sensors,and develop several structure models to help design high performance micro-nano-structure SPR sensing elements.We expound the SPP dispersion equation and the basic properties of Surface Plasmon Wave(SPW),build theoretical modes of both prism-based and optical fiber-based SPR sensors,analyze the localized surface plasmon resonance(LSPR)dispersion model,and introduce the numerical algorithm for designing metal micro-nano structure-based SPP devices and the dispersion model of metal materials.2.According to the simulations of the metal layer SPR sensing structure,we design and implement a SPR chip with Ag/Au six multilayer.The sensing performances are optimized by changing the metal material parameters,and then utilize the SPR chip to specifically make the quantitative detection of glycoprotein molecules.We first use the self-designed wavelength-interrogation-based SPR system and the miniaturized fiber optic SPR system for detection,respectively.Compare the results with those obtained using pure Au layer structure,pure Ag layer structure,and the Ag/Au multilayer structure.It is shown that the last structure has better antioxidant capacity and sensing performances than pure Au layer structure.Next,we test the specific binding of concanavalin A(Con A)through modifying the metal film with ribonuclease B(RNase B).We also analyze the kinetic constants of protein binding and dissociation process,and show that the lowest detection concentration of Con A is 0.001 mg/ml.3.We propose and demonstrate a simple self-assemble methodology relying on a thin block copolymer film of poly(styrene-b-4-vinylpyridine)(PS-b-P4VP)to immobilize gold nanoparticles(AuNPs)on the optical fiber substrate to develop a LSPR sensing element.The PS-b-P4VP based LSPR sensor is deployed to realize the specific recognition and quantitative detection between immunoglobulin antigen(IgG)and its antibody.In comparison with standard AuNP deposition methods using(3-aminopropyl)trimethoxysilane(APTMS)and polyelectrolytes,the sensitivity with the PS-b-P4VP method is found to be 3-fold better,because of the smaller gap between particles and the presence of fewer AuNP aggregates.The procedure is applied to different sizes of AuNPs to form a monolayer of well-dispersed AuNPs with high uniformity and density in order to study the influences of the particle sizes and the distance between particles on the performances of the sensors.We find that the refractive index sensitivity of resonace wavelength increases with larger nanoparticle diameter and smaller gap between particles.This experimental observation is consistent with the simulated result by using FDTD solutions.Compared with other LSPR sensors,the PS-b-P4VP based LSPR sensor has better sensitivity performance for biomolecule detection,and the limit of detection for IgG sample is 0.16 ?g/ml.4.Utilizing 2D nanoplasmonic substrates enhanced effect in transmission spectroscopy,we design and fabricate a gold-coated nanodisk arrays structure,and realize label-free hybridization detection of single-stranded DNA(ssDNA)with low concentration.Based on transmission configuration,we study the effect of azimuth angle and incident angle for the resonance modes.We also prove that the resonance mode(1.0)had low penetration depth and high surface sensitivity under large incident angles.Their excellent properties can be further improved with plasmonic coupling of AuNPs on gold-coated nanodisk arrays excited at large incidence angles.Hybridization between ssDNA immobilized on the surface of the AuNPs and the capture ssDNA on the gold-coated nanodisk arrays demonstrates a signal enhanced DNA hybridization system.By using this system,we measure the label-free DNA fragment of rifampicin resistance tuberculosis,and the limit of detection is 7 pM.Finally,we summarize the entire thesis,including all the research contents,innovation aspects,and further work. |
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