Magnetism in gold nanoparticles

Nealon, Gareth L.; Donnio, Bertrand; Gréget, Romain; Kappler, J.P.; Terazzi, Emmanuel; Gallani, Jean‐Louis

doi:10.1039/c2nr30640a

Cited by 201 publications

(200 citation statements)

References 129 publications

(162 reference statements)

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“…In particular the magnetism seen with other methods 12 peaks at much smaller sizes on the order of 2 nm where the Fermi wave vector (k F = 1.2 nm −1 ) is close to the inverse diameter. Also the magnetism is strongly affected by capping 13 and our samples have no capping.…”

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confidence: 99%

“…This is often addressed by adding an organic capping layer. Magnetism is observed in thiol-capped GNPs, [12][13][14] yet it is often attributed primarily to the gold sulfur bond present in such compounds instead of the finite size of the GNP. There are only a few studies investigating magnetism in uncapped GNPs, [15][16][17][18] and with para-, ferro-, and ferrimagnetism reported, there is no consensus.…”

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confidence: 99%

“…While bulk gold is diamagnetic, theories predict and recent studies report ordered magnetism in GNPs. 12 However, the precise nature and origin of this magnetism are unclear, and the huge discrepancy between various experimental results still lacks a conclusive explanation. A key problem in studying GNPs is that they tend to aggregate.…”

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confidence: 99%

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Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

Dehn

Arseneau

Böni

et al. 2016

The Journal of Chemical Physics

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Chemisorption of muonium onto the surface of gold nanoparticles has been observed. Muonium (μ+e−), a light hydrogen-like atom, reacts chemically with uncapped 7 nm gold nanoparticles embedded in mesoporous silica (SBA-15) with a strong temperature-dependent rate. The addition rate is fast enough to allow coherent spin transfer into a diamagnetic muon state on the nanoparticle surface. The muon is well established as a sensitive probe of static or slowly fluctuating magnetic fields in bulk matter. These results represent the first muon spin rotation signal on a nanoparticle surface or any metallic surface. Only weak magnetic effects are seen on the surface of these Au nanoparticles consistent with Pauli paramagnetism.

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confidence: 99%

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confidence: 99%

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Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

Dehn

Arseneau

Böni

et al. 2016

The Journal of Chemical Physics

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“…nanomedicine | hybrid nanoparticle | cancer nanotechnology | gold quantum dots | mesoporous silica A lthough gold's potential in nanotechnology has been recognized for many decades (1,2), new insights into the unique properties of gold nanoparticles (NPs) of less than 2 nm have just recently started to emerge (3,4). Such extremely small gold NPs could be transformative for a broad set of applications ranging from energy production and storage to catalysis and health care (3).…”

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confidence: 99%

Gold–silica quantum rattles for multimodal imaging and therapy

Hembury

Chiappini

Bertazzo

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

111

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Gold quantum dots exhibit distinctive optical and magnetic behaviors compared with larger gold nanoparticles. However, their unfavorable interaction with living systems and lack of stability in aqueous solvents has so far prevented their adoption in biology and medicine. Here, a simple synthetic pathway integrates gold quantum dots within a mesoporous silica shell, alongside larger gold nanoparticles within the shell's central cavity. This "quantum rattle" structure is stable in aqueous solutions, does not elicit cell toxicity, preserves the attractive near-infrared photonics and paramagnetism of gold quantum dots, and enhances the drug-carrier performance of the silica shell. In vivo, the quantum rattles reduced tumor burden in a single course of photothermal therapy while coupling three complementary imaging modalities: near-infrared fluorescence, photoacoustic, and magnetic resonance imaging. The incorporation of gold within the quantum rattles significantly enhanced the drug-carrier performance of the silica shell. This innovative material design based on the mutually beneficial interaction of gold and silica introduces the use of gold quantum dots for imaging and therapeutic applications.nanomedicine | hybrid nanoparticle | cancer nanotechnology | gold quantum dots | mesoporous silica A lthough gold's potential in nanotechnology has been recognized for many decades (1, 2), new insights into the unique properties of gold nanoparticles (NPs) of less than 2 nm have just recently started to emerge (3, 4). Such extremely small gold NPs could be transformative for a broad set of applications ranging from energy production and storage to catalysis and health care (3). As the size of gold NPs decreases below 2 nm, the quantization of their conduction band leads to molecule-like properties (3). These quantum-sized gold NPs (or gold quantum dots, AuQDs) absorb light in the near-infrared (NIR) biological window (650-900 nm) (2) and convert it into photons and heat (5). Furthermore, whereas bulk gold is diamagnetic, some AuQDs exhibit magnetic properties (4, 6). However, the clear therapeutic and imaging potential of AuQDs in vivo has been undermined by their unfavorable biointeractions and lack of stability in aqueous solvents (5, 7). In biological environments AuQDs tend to aggregate rapidly, reverting to larger gold nanoparticles (AuNPs) (8) and/or bind to protein, which negatively affects their cytotoxicity (7). To retain their advantages, AuQDs require a protective, stabilizing framework that allows proficient biological interactions.Recently, new emphasis has been placed on hybrid NP systems, where multiple nanomaterials are assembled to create multimodal systems that exhibit the combined qualities of the component modules (9-11). These constructs promise to integrate various functionalities by incorporating different nanomaterials into a single, efficient, multimodal system (12, 13). However, these systems usually accumulate the specific functionalities of their component modules through multiple steps in their ...

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“…Among these, AuNps have remarkable attention. AuNps are extensively used in electronics (Homberger and Simon 2010), magnetic (Nealon et al 2012), optics (Tajdidzadeh et al 2017), homo and heterogeneous catalysis (Li et al 2013), and in the field of biology (Ghosh et al 2008;Safavi et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and study of catalytic application of l-methionine protected gold nanoparticles

et al. 2017

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Gold nanoparticle is growing class of nanotechnology due to large number of uses. We synthesized stable L-methionine protected gold nanoparticles (AuNps) by in situ reduction of HAuCl 4 using sodium borohydrate as reducing and L-methionine as stabilizing agent in an aqueous medium. Different parameters (pH, capping agent, precursor salt, and heating time) were optimized to see the effect on the size of particles. Double beam spectrophotometer was used to carry out the spectroscopic studies. It was observed that pH and concentration of reducing salt are deciding factors in controlling the size and morphology of AuNps. Scanning electron microscopy (SEM) verified the formation of AuNPs as predicted by UV-Vis spectra. The interaction of AuNPs with L-methionine was confirmed by Fourier Transform Infrared (FTIR). The reduction of 4-nitrophenol acted as standard of reaction to check the response of AuNps catalyst. Complete reduction of 4-nitrophenol was accomplished by AuNps sol in just 60 s. Fastest reduction rate was observed with smaller spherical particles. This study concluded that size and shape of AuNps can be monitored by controlling the pH, concentration of capping and reducing agent. It also provides an economical solution to aquatic environment in terms of time saving and use of small volume of catalytic solution for reduction of several other toxic organic pollutants.

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Magnetism in gold nanoparticles

Cited by 201 publications

References 129 publications

Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

Gold–silica quantum rattles for multimodal imaging and therapy

Synthesis and study of catalytic application of l-methionine protected gold nanoparticles

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