FTIR study of surfactant bonding to FePt nanoparticles

Shukla, Nisha; Liu, Chao; Jones, Paul M.; Weller, D.

doi:10.1016/s0304-8853(03)00469-4

Cited by 260 publications

(202 citation statements)

References 14 publications

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“…This is supported by the peak due to C-N stretching vibration changing from 1251 to 1261 cm -1 and the N-H bending vibration peak in SPIONs@Au-Cysteamine at 806 cm -1 changing to a weak broad peak at 804 cm -1 after binding to LHRH. 21 - 22 The binding of cysteamine to Au shells and LHRH to cysteamine is also confirmed by XPS studies ( Figure S5). …”

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confidence: 58%

Magnetic Gold Nanoshells: Stepwise Changing of Magnetism through Stepwise Biofunctionalization

Kumar

Mohammad

2010

J. Phys. Chem. Lett.

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We report step-wise changing of magnetic behavior of iron oxide core gold shell nanoparticles from super paramagnetic to permanent magnetism at room temperature, on step-wise biofunctionalization with leutenizing hormone and releasing hormone (LHRH) through cysteamine linker. The observed permanent magnetism at room temperature in LHRH-capped gold nanoshells provides opportunities to extend fundamental investigations of permanent magnetism to other novel nanostructures and biofunctionalized nano gold architectures, simultaneously opening the way to newer applications, especially to those in biomedicine. KeywordsIron oxide nanoparticles; SPION; Gold nanoshell; SPION@Au; Thiol capping; leutenizing hormone and releasing hormone (LHRH); Biofunctionalization It is well known that bulk gold is diamagnetic due to counteraction of paramagnetic behavior of conduction electrons by orbital and ionic core diamagnetism. On the other hand, single gold atoms are paramagnetic because of the unpaired 6s electron. 1 There is a distinct change in the magnetism as one goes from gold atoms to nano gold and further to bulk gold and these fundamental changes in the magnetism are interesting from basic research as well as practical applications. Adding to this is recently reported chemically induced ferromagnetism in thiol-capped gold nanoparticles. 2 The chemically induced permanent magnetism was also extended to Ag and Cu nano clusters. 3 The surprising induction of permanent magnetism, under some conditions of chemisorptions, in small nanoparticles of a bulk-diamagnetic metal is likely through an interaction of s and p orbitals of adsorbates such as thiolates with 5d-orbitals of metal atoms. This interaction is anticipated to lead to emergence of 5d-localized holes as a result of significant charge transfer occurring from the metal atoms to sulfur atoms in the adsorbate molecule. The Au L3-edge extended X-ray absorption near-edge structure (EXAFS) measurements confirm the existence of these holes in Au nanoparticles capped with thiolates. 4 , 5 This interaction between the orbitals of S and Au is ultimately responsible for the onset of magnetism in thiol-capped gold nanoclusters. Recent literature reports indicate that different types of thiol-capped Au nanoparticles showed a great variety of effects going from giant paramagnetism, 6 superparamagnetism, 7 and even to permanent magnetism. 2 , 8 * Corresponding Author: To whom correspondence should be addressed. ckumar1@lsu.edu . Supplementary Figures S1-S7 and Table S1. This material is available free of charge via the Internet at http://pubs.acs.org. We synthesized SPIONs (Fe 3 O 4 ) and gold coated SPIONs (Fe 3 O 4 @Au) modifying the procedure described previously. 16 The SPIONs@Au nanoparticles were purified magnetically making them free of unwanted residual amount of pure Au nanoparticles. The HRTEM measurements show their spherical nature and the mean size of SPIONs@Au is 6.3 ± 0.7 nm compared to 5.4 ± 0.4 nm for SPIONs (Figure 1 and S1). The particles are well dispersi...

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confidence: 58%

Magnetic Gold Nanoshells: Stepwise Changing of Magnetism through Stepwise Biofunctionalization

Kumar

Mohammad

2010

J. Phys. Chem. Lett.

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“…2). Ex situ IR analysis of FePt nanoparticles prepared with oleic acid and oleylamine suggest the presence of oleylamine molecules at the surface, from absorption at 3300 and 1593 cm À1 [16]. However, this does not mean that the same peak positions are necessarily expected here, nor that surfactant adsorption has to be the same on magnetite.…”

Section: Discussionmentioning

confidence: 78%

Surface analysis of magnetite nanoparticles in cyclohexane solutions of oleic acid and oleylamine

Klokkenburg

Hilhorst

Erné

2007

Vibrational Spectroscopy

141

107

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The surface of magnetite (Fe 3 O 4 , d ¼ 6:3 AE 0:7 nm) nanoparticles dispersed in cyclohexane was studied in the presence of oleic acid and oleylamine using in situ FTIR spectroscopy. Equimolar mixtures of these surfactants are widely used in the chemical synthesis of nanoparticles with a low polydispersity. Here, the IR spectra indicate that oleic acid molecules adsorb to the magnetite surface as a carboxylate. Measurements as a function of surfactant concentration yield an adsorption isotherm, with about two surfactant molecules adsorbed per nm 2 of magnetite at 1 mM surfactant concentration and about 3.5 molecules per nm 2 at 310 mM, of the order expected for full monolayer coverage. No spectral indication is found of oleylamine molecules at the surface of magnetite. In solution, however, almost every oleylamine molecule combines with an oleic acid molecule to form an acid-base complex, with an association constant of 3:5 Â 10 4 dm 3 mol À1 .

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“…In addition, the FTIR spectrum of the composite Fe 3 O 4 nanoparticles shows that the peak at 1710 cm 21 for carbonyl of PAA segments was shrank and two new peaks at 1452 and 1405 cm 21 appeared due to the binding of the carboxylic acid groups to the surface of the nanoparticles to form carboxylate groups, 24 these new peaks corresponded to the COO 2 antisymmetric vibration and the COO 2 symmetric vibration indicated the bidentate bonding of the carbonyl groups to the surface Fe atoms. 25,26 The remaining but shrunken peak at 1710 cm 21 for C¼ ¼O stretch indicated some fraction of the PAA segments were bonded to nanoparticles either in monodentate form or as an acid. 25,26 It can also be observed that when the amount of polymer in the composite Fe 3 O 4 nanoparticles was increased to 30 wt %, the bonds of aliphatic acid at 1105-1159 cm 21 appeared.…”

Section: Resultsmentioning

confidence: 99%

Preparation of poly (ethylene oxide)‐graft‐poly (acrylic acid) copolymer stabilized iron oxide nanoparticles via an in situ templated process

Huang

2008

J of Applied Polymer Sci

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Superparamagnetic iron oxide nanoparticles were prepared in the presence of poly (ethylene oxide)-graft-poly (acrylic acid) copolymers via an in situ templated coprecipitation process. The resulted composite nanoparticles consisted of clusters of iron oxide monocrystals embedded inside the polymer chains, and were highly dispersible in aqueous solution. In these graft copolymers, the PAA segments were chemisorbed onto the Fe 3 O 4 nanoparticle surface through their carboxylic acid groups by forming carboxylate groups with the Fe atoms, while PEO segments as the stabilizers extended into the water matrix.Thus the composite nanoparticles exhibited narrow size distribution by the dynamic light scattering measurement. X-ray diffraction and magnetometer data confirmed the crystalline structure and superparamagnetic property of the particles. This procedure provided a good choice for preparing stable iron oxide magnetic nanoparticles with PEO modified surfaces.

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FTIR study of surfactant bonding to FePt nanoparticles

Cited by 260 publications

References 14 publications

Magnetic Gold Nanoshells: Stepwise Changing of Magnetism through Stepwise Biofunctionalization

Magnetic Gold Nanoshells: Stepwise Changing of Magnetism through Stepwise Biofunctionalization

Surface analysis of magnetite nanoparticles in cyclohexane solutions of oleic acid and oleylamine

Preparation of poly (ethylene oxide)‐graft‐poly (acrylic acid) copolymer stabilized iron oxide nanoparticles via an in situ templated process

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