| Summary: | 博士 === 國立中興大學 === 化學系所 === 102 === Surface-enhanced Raman spectroscopy is an important technique that have been used in different fields because of its high sensitivity, ability to produce distinct spectra from molecules of similar structure and function, and the elimination of expensive reagents or time-consuming sample preparation steps. Choice and fabrication of SERS substrates are the critical issues that due attention should be given. Thus, different methods have been reported in the preparation of noble metal nanostructures for SERS applications. In this work magnetic structures have been integrated with noble metal nanostructures and employed as SERS substrates for detection of biologically important species .In this thesis, the works are presented in five chapters.
In the first chapter concepts related to Raman scattering, SERS, methods of preparation of SERS substrates, magnetic nanoparticles, and SERS applications are presented briefly.
The second chapter deals with preparation of magnetic microspheres that are decorated with silver nanoparticles for SERS detection of nucleobases. For the preparation of the SERS substrates, initially the magnetic nanoparticles were prepared by coprecipitation of iron (II) and iron (III) solutions with subsequent suspension polymerization reaction of divinyl benzene and methyl methacrylate that resulted in a polymer coated magnetic microspheres. Photochemical reduction method was employed for the formation of AgNPs. To optimize the substrate para-Nitrothiophenol (pNTP) was used as a probe molecule. Further, the substrate was also used in detection of nucleobases in aqueous solution.
In chapter three, preparation of gold decorated magnetic microspheres for SERS application is presented. Gold nanoparticles are easily attached to the magnetic microspheres by exposing the reaction mixture containing magnetic microspheres, HAuCl4, and trisodium citrate solutions with UV light. The formation and deposition of gold nanoparticles are confirmed by the SERS activity of the substrate, from the distinct SEM images of the gold nanoparticles and from the XRD patterns. The substrates prepared by the optimized conditions were applied for the determination of some nucleobases.
Development of multifunctional hybrid structures comprising magnetic nanoparticles, ZnO, and silver nanocrystals for SERS determination of creatinine and uric acid are presented in chapter four. Precipitation of Zn (NO3)2 with NaOH in the presence of magnetic nanoparticles resulted in a composite structure having magnetic and catalytic properties. UV light exposure of the mixture containing AgNO3 solution (dissolved in ethylene glycol) and ZnO/Fe3O4 composite resulted in formation of silver nanocrystals onto the composite that owes optical property. Formations of these structures are confirmed from XRD and EDX data. To examine the performance of the prepared substrate for SERS activity, pNTP was used. The substrate also used to determine creatinine and uric acid in aqueous solutions as well as in urine.
In the last chapter the concluding remarks for the work are given. Thus, in this work, magnetic structures have been used as a plat form to embed metallic nanostructures for SERS applications. Development of these hybrid structures based on magnetic structures offer properties that are basically important for SERS measurements that would have not been obtained only from a single component counterpart. The ease to collect the particles from the reaction mixture using magnet without centrifugation or filtration makes SERS measurements simple.
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