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Yan Xing,Xiao-Hui Bai,Ming-Li Peng,Xiang-Rong Ma,Norbert Buske,Ya-Li Cui 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.10
Fe3O4/Au nanocomopsites (Fe3O4/Au NPs) with much improved catalytic activity were successfully fabricated through a simple seed growth method in aqueous solution. The petal-like structure, high saturation magnetization, the negatively charged sodium citrate-stabilized Fe3O4/Au NPs was characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), dynamic light scattering (DLS) and vibrating sample magnetometry (VSM). The activated-H2O2 ability of Fe3O4/Au NPs was evaluated by using methylene blue (MB) as a cationic phenothiazines dye to be degraded in near neutral solution. The results showed Fe3O4/Au NPs removed over 95% MB from an aqueous solution within 60 min under the optimum conditions. The apparent rate constant of Fe3O4/Au NPs was 10.8 x 10 -2 min -1 which was 43.2 and 8.3 times higher than pure Fe3O4 (2.5 x 10 -3 min -1) and Au (1.3 x 10 -2 min -1) NPs. The enhanced catalytic activity and increased oxidation rate constant probably owing to the synergistic effect between Fe3O4 and Au NPs to activate H2O2 generate a large amount of strong oxidizing species, such as ·OH. In addition, nanocrystalline structure of Fe3O4/Au NPs was also very important to the peroxidase-like effect, especially the interaction interface between Fe3O4 and Au NPs. Moreover, Fe3O4/Au NPs was stable and could be regenerated and reused for at least five cycles.
Highly Sensitive Detection of Malathion Based on FRET between Au/Fe3O4 and Rhodamine B
Di Jia,Dongqing Ma,Xiaodong Du,Lijuan An 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.8
In this paper, Au/Fe3O4 nanoparticles (Au/Fe3O4 NPs) were prepared and a method for detecting malathion was constructed based on fluorescence resonance energy transfer (FRET) between Au/Fe3O4 NPs and Rhodamine B (RhB). RhB could be electrostatically adsorbed to the surface of Au/Fe3O4 NPs resulting in a low fluorescent background. The malathion hydrolysate with -SH can compete with RhB to form a stronger Au─S bond, thereby promoting the desorption of RhB from the surface of Au/Fe3O4 NPs. This process causes the fluorescence emission to recover. The result demonstrated that fluorescence quenching efficiency of Au/Fe3O4 could reach 50% at 579?nm and the fluorescence recovery efficiency of malathion hydrolysate could reach 61% at 579?nm. The limit of detection (LOD) of malathion was as low as 0.59 ?M. The linear range of detection was 27.24?99.89 ?M. Au/Fe3O4 NPs could be reused by a magnetic concentration-washing process.
Magnetic-Assembly Mechanism of Superparamagneto-Plasmonic Nanoparticles on a Charged Surface
Tran, Van Tan,Zhou, Hongjian,Lee, Seunghun,Hong, Seong Cheol,Kim, Jeonghyo,Jeong, Se-Young,Lee, Jaebeom American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.16
<P>One-dimensional magnetoplasmonic nanochains (MPNCs) were self-assembled using Au-coated Fe<SUB>3</SUB>O<SUB>4</SUB> core–shell superparamagnetic nanoparticles (Fe<SUB>3</SUB>O<SUB>4</SUB>@Au NPs) by applying an external static magnetic field. The assembly mechanism of the Fe<SUB>3</SUB>O<SUB>4</SUB>@Au NPs was investigated thoroughly, revealing that substrate–particle interactions, van der Waals forces, and magnetic forces play important roles in the formation and control of the MPNCs. Magnetic force microscopy (MFM) and vibrating sample magnetometry (VSM) were used to study the magnetic properties of the MPNCs, which were compared with those of Fe<SUB>3</SUB>O<SUB>4</SUB> nanochains.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-16/acsami.5b00904/production/images/medium/am-2015-00904e_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b00904'>ACS Electronic Supporting Info</A></P>
SURFACE MODIFICATION AND CHARACTERIZATION OF Fe_3O_4/Au COMPOSITE NANOPARTICLES
FENG SHI,WENLI HUI,YALI CUI,CHAO CHEN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.2
Fe_3O_4/Au composite nanoparticles were modified with α-thio-ω-carboxy poly (ethylene glycol). Results from XRD, selected area diffraction, high-resolution TEM images, and dynamic lighting scattering illustrate that the particles have a core/shell composite structure and were monodispersed. Surface plasmon resonance measured by UV–Vis indicates that the absorption peak of the modified composite particle characteristic at 532 nm can be stably suspended in a different buffer. The modified composite particles also have good response to external magnetic field. The Fe_3O_4/Au composite nanoparticles are magnetically and optically active, and are useful for simultaneous magnetic and optical detection. Coupled with biomolecules, the advantages of these composite particles make them very promising for biomedical applications in the near future.
Silver-enhanced conductivity of magnetoplasmonic nanochains
TRANVANTAN,Hongjian Zhou,박중연,김종만,이재범 한국물리학회 2015 Current Applied Physics Vol.15 No.2
A method for improving the electrical properties of one-dimensional conducting structures by reductive deposition of metallic silver on a gold surface is presented. Fe3O4@Au coreeshell nanoparticles were used to fabricate conducting magnetoplasmonic nanochains (MPNCs) through magnetic-field-induced assembly. The MPNCs were prepared on a solid substrate. Their dimension was controlled by adjusting the pH of the colloidal solution. The nanochains (NCs) were placed across gold microelectrodes, and additional metal was deposited by highly specific chemical enhancement of the colloidal gold using a silver enhancement solution. Silver-enhanced MPNCs show a remarkable morphology and an impressive enhancement in electrical properties compared to the as-prepared MPNCs.