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Preparation High Sensitive SERS-active Optical Fiber Sensor and Application

Author: LiuChunYu
Tutor: XuWeiQing; XuShuPing
School: Jilin University
Course: Physical and chemical
Keywords: Optical-fiber SERS sensor Laser-inducement method Polymerization insitu Polymer porous materials High sensitive sensor
CLC: TP212
Type: PhD thesis
Year: 2013
Downloads: 98
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Abstract

Surface-enhanced Raman scattering (SERS) is a fast and ultrasensitive scatteringspectra technique, has been widely applicable to single molecule detection, pesticidetracing, protein tests, pharmacy, biosensing, and art authentication, etc. SERS requiresminimal sample preparation and is non destructive to sample which allows real timeanalysis and great potential for multi components analysis. The morphology of themetallic structure plays a major role in determining the magnitude of signalenhancement and sensitivity of detection. The preparation of SERS substrates is anessential subject in SERS study. Some researchers employed the laser-induced Ag/Audeposition method to quickly construct an Au/Ag NP film on glass substrate for SERS.Optical fibers have long been the interest of analytical chemists. Through the fiber,signal and light can be transmitted to several kilometers without noticeable loss. It ischemically stable, and is not susceptible to environmental changes. Sensors based onsurface-enhanced Raman scattering (SERS) and optical fiber probes have been usedin chemical and biological detection and sensing due to their unique advantages, suchas their low cost, flexibility, reliability, and also remote sensing capabilities.Based on above view, my study is outlined as follows:1. Preparation of SERS-active optical fiber by laser-induced Ag depositionand its application for the bioidentification of biotin/avidinWe applied the SERS-active fiber prepared by the photochemical Ag NPdeposition to the bioidentification of avidin/biotin. First, we optimized thelaser-induced conditions for the fabrication of SERS-active Ag NP layer. The reflection spectroscopy and scanning electron microscope (SEM) were used tocharacterize the plasmonic property and the morphology of the formed SERS-activeAg NP layer. The optical fiber with laser-induced Ag film was used for monitoring thebiotin/avidin identification process. Since biotin gave weak Raman signals and nofingerprint information was provided in the direct detection of biotin, we used a dyemolecule labeled biotin (Atto610-biotin), which supported strong Raman activity dueto the fluorescent quenching effect when it was assembled on the Ag film surface bythe specific identification of avidin. The concentration-dependent SERS spectra ofAtto610-biotin were recorded and the working curve was obtained. The lowestdetection concentration of Atto610-biotin by using this SERS-active optical fiber wasas low as10-7mg/mL.2. Fabrication of SERS-acitve optical fiber sensor by in situ thermalpolymerization of porous material and its apllicationPolymer porous was preparing with the thermal polymerization method in the tipof the ordinary multimode fiber in situ. Silver nanoparticles film was deposited withthe laser-inducement method in the porous material of the tip fiber for preparation ofhigh SERS-active polymer porous fiber sensor. The metal nanoparticle aggregatescontaining many “hot spots” suspended in solution can present a large total surfacearea, thus facilitating effective interactions with analytes and generation of strongRaman scattering emission. In comparison to SERS sensing using nanostructuredmetal films, which are inherently planar detectors, this approach allows direct probingof analytes within a defined volume of solution, thereby providing higher sensitivity.Porous material laser-induce SERS-active fiber technology has high sensitivity,remotely, on line, real-time and non-destructive can apply the process monitoring,micro-fluidic chip, environmental testing, clinical monitoring and bio-pharmaceuticalfield.3. Preparation and study on the SERS-active fiber pH sensor withlaser-inducement deposition silver nanoparticle film We provide a method of photochemical modification of an optical fiber tip with asilver nanoparticle film.4-MBA and4-Mpy were absorbed by optical fiberSERS-active layer for pH sensor. SERS spectrum changes were monitored in differentpH values solution with SERS-active fiber. In the course of the study, we found that4-Mpy Raman peaks at1619cm-1was blue shift with pH value increases, inferred4-Mpy molecules in different pH solutions has vary the angle with the silver film.4-Mpy molecule was perpendicular with the silver film in acidic solution, and itproduces a certain inclination in the neutral and alkaline solution.

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