Low-temperature synthesis and characterization of PVP-capped FeAu nanoparticles
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JunHua Wua) Pioneer Research Center for Biomedical Nanocrystals, Korea University, Seoul 136-713, Korea (Received 28 February 2011; accepted 2 May 2011)
We report the low-temperature synthesis and characterization of polyvinylpyrrolidone (PVP)-capped FeAu magneto-plasmonic multifunctional nanoparticles by a one-step nanoemulsion process. The Fourier transform infrared spectroscopy study proves the PVP coating on the surface of the resultant FeAu nanoparticles, whereas the structural, magnetic, and optical analysis illustrates the fusion of iron and gold into one single nanostructure showing the nanoparticle shape and a tight size distribution with an average size of 11.3 nm, followed by the growth habit compared to other relevant nanoparticles. Moreover, the PVP-capped FeAu nanoparticles manifest soft ferromagnetic behavior with a small coercivity of ;40 Oe at room temperature. The corresponding magnetic hysteresis curves were elucidated by modified bi-phase Langevin equations, which were reasonably interpreted with the binary particle size distribution. The nanoparticles reveal a well-defined surface plasmon resonance band at ;546 nm and a visual demonstration shows the magnetic separability of all nanoparticles for potential magnetic and/or optical manipulation.
I. INTRODUCTION
Nanoparticles of multiple constituents have gained a prominent momentum in the interdisciplinary convergence of biology and medicine with physical sciences and nanotechnology, in view of prospective application and fundamental challenge in many areas such as multifunctional nano-carriers and nanoscale building blocks.1–7 In particular, bimetallic alloy nanoparticles are fascinating nanostructured materials attributed to their special structure and properties and have found widespread use in chemical detection, biological sensing, catalysis, photoelectronic devices, medicine, and information storage. In binary candidates, two elements, iron and gold, are of great significance in constructing such binary nanostructures.8 Physicochemically, iron is an excellent material owing to its high magnetization and easy conversion to biocompatible oxides, which have been thoroughly studied in the form of magnetic nanoparticles in the biomedical field.9,10 In fact, the binary nanoparticles containing Fe have been mostly investigated in consideration of unique properties other than their bulk counterparts resulting from reduced dimension.11–13 On the contrary, gold shows attractive optical properties, biological compatibility, catalytic activity, and excellent surface effects.14–16 Uniquely, nanostructured gold reveals a strong a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2011.161 2040
J. Mater. Res., Vol. 26, No. 16, Aug 28, 2011
http://journals.cambridge.org
Downloaded: 09 Feb 2015
absorption band in the visible region as a result of surface plasmon, which is defined by the particle size and the physicochemical environment surrounding the nano-entity. The phenomenon has been used in biomolecular colo
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