Magnetic Force Microscopy in Liquids

Ares, Pablo; Jaafar, Miriam; Gil, Adriana; Gómez-Herrero, Júlio; Asenjo, A.

doi:10.1002/smll.201500874

Cited by 29 publications

(28 citation statements)

References 37 publications

(49 reference statements)

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“…We employed a cantilever holder that minimizes the spurious resonance frequencies that often appear when working in liquids (see ESI of ref. 39). This allowed us to determine the resonance frequency from a frequency sweep in good agreement with the resonance frequency value obtained by measuring the cantilever thermal noise.…”

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confidence: 99%

High resolution atomic force microscopy of double-stranded RNA

et al. 2016

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Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: ABSTRACT: Double-stranded (ds) RNA mediates suppression of specific gene expression, it is the genetic material of a number of viruses, and a key activator of the innate immune response against viral infections. The ever increasing list of roles played by dsRNA in the cell and its potential biotechnological applications has raised over the last decade an interest for the characterization of its mechanical properties and structure, and that includes approaches using Atomic Force Microscopy (AFM) and other singlemolecule techniques. Recent reports have resolved the structure of dsDNA with AFM at unprecedented resolution. However, an equivalent study with dsRNA is still lacking. Here, we have visualized the double helix of dsRNA under near-physiological conditions and at enough resolution to resolve the A-form subhelical pitch periodicity. We have employed different high-sensitive force-detection methods and obtained images with similar spatial resolution. Therefore, we show here that the limiting factors for high-resolution AFM imaging of soft material in liquid medium are, rather than the imaging mode, the force between tip and sample and the sharpness of the tip apex.

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confidence: 99%

High resolution atomic force microscopy of double-stranded RNA

et al. 2016

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“…Imaging magnetic nanoparticles in liquid served as a proof of principle for using MFM to image magnetic nanoparticles within cells in order to better understand their distribution and behavior in a physiologically relevant environment. Another recent study published from the Universidad Autonoma de Madrid in Spain reported successful MFM imaging of nanoparticles in liquid [23]. In this study, MFM was used to not only image these nanoparticles, but to optimize the MFM signal acquisition in liquid media so that it could be applied to the characterization of magnetic nanoparticles and their magnetic signals.…”

Section: Magnetic Force Microscopy For Nanoparticle Characterizationmentioning

confidence: 97%

“…Perhaps most notably, MFM is capable of operating under ambient conditions, at varying temperatures, ultrahigh vacuums, as well as liquid environments [3,23] while still providing resolution to less than ten nanometers. This is essential because it allows magnetic nanoparticles to be localized and characterized in vitro [24] or inside polymer films and cell-like systems [3,25,26].…”

Section: Magnetic Force Microscopy For Nanoparticle Characterizationmentioning

confidence: 99%

“…In this study, MFM was used to not only image these nanoparticles, but to optimize the MFM signal acquisition in liquid media so that it could be applied to the characterization of magnetic nanoparticles and their magnetic signals. They were able to image the magnetic domains of hard disk drives as well as DMSA-coated Fe3O4 ferromagnetic nanoparticles in both air and liquid environments ( Figure 6) [23]. To maximize the MFM signal in drive amplitude modulation mode for AFM, the group varied relevant measuring and operating conditions such as cantilever oscillation amplitude, set point, and Z lift distance.…”

Section: Magnetic Force Microscopy For Nanoparticle Characterizationmentioning

confidence: 99%

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Magnetic Force Microscopy for Nanoparticle Characterization

Cordova¹,

Lee²,

Leonenko³

2016

NanoWorld J

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Since the invention of the atomic force microscope (AFM) in 1986, there has been a drive to apply this scanning probe technique or a form of this technique to various disciplines in nanoscale science. Magnetic force microscopy (MFM) is a member of a growing family of scanning probe methods and has been widely used for the study of magnetic materials. In MFM a magnetic probe is used to raster-scan the surface of the sample, of which its magnetic field interacts with the magnetic tip to offer insight into its magnetic properties. This review will focus on the use of MFM in relation to nanoparticle characterization, including superparamagnetic iron oxide nanoparticles, covering MFM imaging in air and in liquid environments.

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“…13,14 A common downside of all these standard characterization techniques lies on the fact that they only provide average information over a very large number of NPs. S2) [15][16][17][18][19] MFM has proved to be a versatile technique, by means of which it is possible to study the real time evolution of the magnetic domains by variable-field MFM (VF-MFM) 20 or to characterize the evolution of MFM contrast versus the tipsample distance by the 3D mode, allowing a complete characterization of the small structures. S1), thermogravimetric curves for samples R11 and R49 (Fig.…”

Section: Introductionmentioning

confidence: 99%

Superparamagnetic versus blocked states in aggregates of Fe_3−xO₄ nanoparticles studied by MFM

et al. 2015

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Magnetic domain configurations in two samples containing small aggregates of Fe(3-x)O4 nanoparticles of about 11 and 49 nm in size, respectively, were characterized by magnetic force microscopy (MFM). Two distinct magnetic behaviors were observed depending on the particle size. The aggregates constituted of nanoparticles of about 11 nm in size showed a uniform dark contrast on MFM images, reflecting the predominant superparamagnetic character of these particles and arising from the coherent rotation of the spins within the aggregate as the latter align along the tip stray-field. By applying a variable in-plane field, it is possible to induce magnetic polarization yielding an increasing dark/bright contrast as the strength of the applied field overcomes the stray-field of the tip, although this polarization completely disappears as the remanent state is recovered when the magnetic field is switched off. On the contrary, for aggregates of NPs of about 49 nm in size, dark/bright contrast associated with the existence of magnetic domains and magnetic polarization prevails in MFM images all along the magnetic cycle due to the blocking state of the magnetization of these larger particles, even in the absence of an applied field. All in all, we unambiguously demonstrate the capabilities of magnetic force microscopy to distinguish between blocked and superparamagnetic states in the aggregates of magnetic nanoparticles. Micromagnetic simulations strongly support the conclusions stated from the MFM experiments.

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Magnetic Force Microscopy in Liquids

Cited by 29 publications

References 37 publications

High resolution atomic force microscopy of double-stranded RNA

High resolution atomic force microscopy of double-stranded RNA

Magnetic Force Microscopy for Nanoparticle Characterization

Superparamagnetic versus blocked states in aggregates of Fe_3−xO₄ nanoparticles studied by MFM

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Magnetic Force Microscopy in Liquids

Cited by 29 publications

References 37 publications

High resolution atomic force microscopy of double-stranded RNA

High resolution atomic force microscopy of double-stranded RNA

Magnetic Force Microscopy for Nanoparticle Characterization

Superparamagnetic versus blocked states in aggregates of Fe3−xO4 nanoparticles studied by MFM

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Product

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Superparamagnetic versus blocked states in aggregates of Fe_3−xO₄ nanoparticles studied by MFM