Gold-assembled silica-coated cobalt nanoparticles as efficient magnetic separation units and surface-enhanced Raman scattering substrate

Magnetic and optical bifunctional nanoparticles that combine easy separation, preconcentration, and efficient SERS capabilities have been fabricated with high sensitivity and reproducibility through a low-cost method. These gold nanoparticles attached on magnetic silica-coated cobalt nanospheres (Co@SiO2/AuNPs) display the advantage of strong resonance absorption due to gaps at nanoscale between neighboring metal nanoparticles bringing large field enhancements, known as "hot spots". The prepared particles can be controlled by using an external magnetic field, which makes them very promising candidates in biological applications and Raman spectroscopic analysis of dissolved organic species. The magnetic property of the prepared particles lowers the detection limits through preconcentration with solid-phase extraction in SERS analysis. The performance of the prepared nanostructures was evaluated as a SERS substrate using brilliant cresyl blue (BCB) and rhodamine 6G (R6G) as model compounds. The solid-phase affinity extraction of 4-mercapto benzoic acid (4-MBA) using bifunctional Co@SiO2/AuNPs nanoparticles followed by magnetic separation and the measurement of the SERS signal on the same magnetic particles without elution were investigated. Approximately 50-fold increase in SERS intensity was achieved through solid-phase extraction of 8.3 x 10(-6) M 4-MBA in 10 min.


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Kaya, Murat; Volkan, Mürvet (Elsevier BV, 2011-03-15)
A new chloride generation system was designed for the direct, sensitive, rapid and accurate determination of the total germanium in complex matrices. It was aimed to improve the detection limit of chloride generation technique by increasing the vapor pressure of germanium tetrachloride (GeCl4). In order to do so, a novel joint vapor production and gas-liquid separation unit equipped with a home-made oven was incorporated to an ordinary nitrous oxide-acetylene flame atomic absorption spectrometer. Several va...
Phase transition of chemically synthesized FePt nanoparticles under high pressure
ŞİMŞEK, TELEM; Karci, Ozgur; ÖZCAN, ŞADAN (The Scientific and Technological Research Council of Turkey, 2018-01-01)
We present the results of a study related to phase transformation of chemically synthesized FePt nanoparticles under high pressure from face-centered cubic into face-centered tetragonal structure. As-synthesized nanoparticles are around 4.5 nm and show superparamagnetic behavior at 300 K. After annealing under 60 bar pressure of hydrogen at 400 degrees C for 2 h, nanoparticles exhibit strong ferromagnetic behavior with 5391 Oe coercivity. Results show that high-pressure annealing lowers the decomposition te...
Morphology and optical properties of thin silica films containing bimetallic Ag/Au nanoparticles
Yashan, G. R.; Eremenko, A. M.; Smirnova, N. P.; Suzer, S.; Ertaş, Gülay; Tabor, Ch. (Springer Science and Business Media LLC, 2008-11-01)
We have studied the optical spectra in the UV and visible regions, the morphology by scanning electron microscopy (SEM), and the X-ray photoelectron spectra (XPS) of bimetallic Ag/Au nanoparticles incorporated into transparent silicate films in the sol-gel transition stage. The bimetallic nanoparticles, obtained by a combination of photoreduction and thermal reduction, form structures of the alloy or core-shell type.
DOGU, G; CABBAR, C; Doğu, Timur (Informa UK Limited, 1991-01-01)
The single-pellet moment techniques previously developed for the evaluation of effective diffusion coefficient and effective thermal conductivity of a porous solid are combined and a procedure is proposed for the simultaneous evaluation of these constants from a single set of pulse response experiments. It is shown that both temperature and concentration response curves can be measured from a single pulse of oxygen injected into hydrogen carrier gas flowing past a catalyst pellet. It is shown that the zerot...
Flexible organic photovoltaics from zinc oxide nanowires grown on transparent and conducting single walled carbon nanotube thin films
Ünalan, Hüsnü Emrah; Kuo, Daniel; Parekh, Bhavin; Amaratunga, Gehan; Chhowalla, Manish (Royal Society of Chemistry (RSC), 2008-01-01)
The fabrication of flexible organic photovoltaics (OPVs) which utilize transparent and conducting single walled carbon nanotube (SWNT) thin films as current collecting electrodes on plastic substrates in zinc oxide nanowire (ZnO NW)/poly(3-hexylthiophene) (P3HT) bulk heterojunction photovoltaic devices is reported. The bulk heterojunctions for exciton dissociation are created by directly growing ZnO nanowires from solution on the SWNT electrodes and spin coating the P3HT polymer. A maximum OPV power convers...
Citation Formats
L. S. Yıldırım and M. Volkan, “Gold-assembled silica-coated cobalt nanoparticles as efficient magnetic separation units and surface-enhanced Raman scattering substrate,” TURKISH JOURNAL OF CHEMISTRY, pp. 307–318, 2019, Accessed: 00, 2020. [Online]. Available: