Preparation of gold decorated cobalt-silica core-shell nanoparticles for surface enhanced raman scattering applications

Download
2010
Keser, Lütfiye Sezen
Bringing together several materials into a single nanoparticle is an attractive way to design systems that exhibit diverse physical and chemical properties. Cobalt nanoparticles are extensively used in magnetic separation, ferrofluids, and magnetic storage media. The deposition of gold nanoparticles onto cobalt core significantly affects their optical properties due to the introduction of surface Plasmon. Here the synthesis of gold nanoparticles decorated cobalt-silica nanoparticles are reported for the first time. Their optical and magnetic properties and capacity as a surface enhanced Raman scattering (SERS) substrate were investigated. This nano-material is of particular interest as a dual agent allowing both magnetic separation and SERS detection. The synthesis involves three steps: i) synthesis of Co nanoparticles; ii) deposition of a silica shell around the Co core and introduction of amine functional groups on the surface; iii) decoration of the surface with gold nanoparticles. Co nanoparticles were prepared in an inert atmosphere in the presence of capping and reducing agents. Size of the cobalt nanoparticles was varied by changing the concentration of the capping agent. Since cobalt particles are easily oxidized, they were coated with silica shell both to prevent oxidation and allow further functionalization. Silica coating of the particles were performed in water/ethanolic solution of tetraethyl orthosilicate (TEOS). Thickness of silica coating was controlled by varying the concentrations of TEOS. Besides, by adding 3-aminopropyl-triethoxysilane (APTS) to the reaction medium, primarily amine groups were introduced on the silica surface. For further modifications citrate stabilized gold nanoparticles were appended onto the surface of amine modified core-shell cobalt-silica nanoparticles. Gold decorated magnetic core-shell structures were used as SERS substrate with Raman dyes; brilliant cresyl blue (BCB) and rhodamine 6G (R6G). They were also utilized for preconcentration and SERS detection of 4-mercapto benzoic acid (4-MBA). Gold nanoparticles on the silica and thiol group on the 4-MBA were very selective to each other, thus, 4-MBA could be attached on to gold surface and it could be easily separated magnetically from the reaction medium and identified by Raman spectroscopy. Characterization of the cobalt, cobalt-silica and gold modified cobalt-silica nanoparticles was done by Field Emission Scanning Electron Microscopy (FE-SEM), Scanning-Transmission Electron Microscopy (S-TEM), Energy-Dispersive X-ray Spectroscopy (EDX), UV-Vis spectrometry, and Raman microscope system.

Suggestions

Synthesis of colloidal silver particles with different sizes by seeding approach for surface enhanced raman scattering (sers) studies
Sancı, Rukiye; Volkan, Mürvet; Department of Chemistry (2009)
In this study, silver nanorods and nanospheroids were prepared both in aqueous solution and on the surface of glass slides through seed-mediated growth approach at room temperature and used as a surface enhanced Raman scattering (SERS) substrate. The synthesis of metallic nanorods was started with the production of silver nanospheres as seed utilizing sodium borohydride and trisodium citrate as reducing and capping agents, respectively. These seeds were then added to a growth solution containing additional ...
Preparation and characterization of surface enhanced raman scattering substrate through electro deposition of silver-pedot film on ito glass surface
Doğan, Üzeyir; Volkan, Mürvet; Department of Chemistry (2011)
Detection of chemicals is a vital part of chemistry. For this reason, many detection systems are developed by scientists and every detection system has its own advantages. Raman spectroscopy is one of these detection systems having many advantages. However, this technique suffers from low signal intensity disadvantage. By developing a well prepared substrate, this problem can be easily solved; moreover, even single molecule detection can be possible. In this study, a novel surface enhanced Raman scattering ...
New Generation of Solid-Phase Microextraction Coatings for Complementary Separation Approaches: A Step toward Comprehensive Metabolomics and Multiresidue Analyses in Complex Matrices
Gionfriddo, Emanuela; Boyacı, Ezel; Pawliszyn, Janusz (American Chemical Society (ACS), 2017-04-04)
In this work, a new generation of solid-phase microextraction (SPME) coatings based on polytetrafluoro-ethylene amorphous fluoroplastics (PTFE AF 2400) as a particle binder is presented. The developed coating was tested for thermal and solvent-assisted desorption, demonstrating its compatibility with both gas- and liquid-chromatographic platforms. The incorporation of hydrophilic-lipophilic balance (HLB) adsorptive particles provided optimal extraction coverage for analytes bearing a broad range of hydropho...
Determination of cadmium using slotted quartz tube atom trap atomic absorption spectrometry and metal coatings
Özcan Gurbetçioğlu, G. Pelin; Ataman, Osman Yavuz; Department of Chemistry (2010)
Flame atomic absorption spectroscopy (FAAS) is a common technique for detecting metals and metalloids in environmental, biological and metallurgical samples. Although it is a rather old technique, it is still very reliable, simple to use and inexpensive. The technique can be used to determine the concentration of over 70 different metals in a solution. However, it has detection limits at mg/L levels. Some atom trapping methods have been developed to reach the detection limits of ng/mL levels. Slotted quartz...
Magnetic Susceptibility-Based Protein Detection Using Magnetic Levitation
Yaman, Sena; TEKİN, HÜSEYİN CUMHUR (American Chemical Society (ACS), 2020-09-01)
Magnetic levitation, which is a magnetic phenomenon of levitating particles suspended in a paramagnetic liquid under a nonuniform magnetic field, is a powerful tool for determining densities and magnetic properties of micro- and nanoparticles. The levitation height of particles in the magnetic field depends on the magnetic susceptibility and density difference between the object and the surrounding liquid. Here, we developed a magnetic susceptibility-based protein detection scheme in a low-cost and miniatur...
Citation Formats
L. S. Keser, “Preparation of gold decorated cobalt-silica core-shell nanoparticles for surface enhanced raman scattering applications,” M.S. - Master of Science, Middle East Technical University, 2010.