Analysis of the effect of magnetic field gradient on atomic spin polarization and relaxation for optically pumped atomic magnetometers

Magnetic Resonance Imaging (MRI) observes tissue water in the presence of a magnetic field gradient to study morphological changes such as tissue volume loss and signal hyperintensities in human disease. These changes are mostly non-specific and do not appear to be correlated with the range of severity of a certain disease. In contrast, Magnetic Resonance Spectroscopy (MRS), which measures many different chemicals and tissue metabolites in the millimolar concentration range in the absence of a magnetic field gradient, has been shown to reveal characteristic metabolite patterns which are often correlated with the severity of a disease. In-vivo MRS studies are performed on widely available MRI scanners without any “sample preparation” or invasive procedures and are therefore widely used in clinical research. Hydrogen (H) MRS and MR Spectroscopic Imaging (MRSI, conceptionally a combination of MRI and MRS) measure N-acetylaspartate (a putative marker of neurons), creatine-containing metabolites (involved in energy processes in the cell), choline-containing metabolites (involved in membrane metabolism and, possibly, inflammatory processes),

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Magnetic hybrid materials interact with biological matrices

Physical Sciences Reviews ◽

10.1515/psr-2019-0114 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Christine Gräfe ◽

Elena K. Müller ◽

Lennart Gresing ◽

Andreas Weidner ◽

Patricia Radon ◽

...

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Hybrid Materials ◽

Biomedical Application ◽

Magnetic Field Gradient ◽

Apical Cell ◽

Cell Type ◽

Cell Layers ◽

Barrier Model

Abstract Magnetic hybrid materials are a promising group of substances. Their interaction with matrices is challenging with regard to the underlying physical and chemical mechanisms. But thinking matrices as biological membranes or even structured cell layers they become interesting with regard to potential biomedical applications. Therefore, we established in vitro blood-organ barrier models to study the interaction and processing of superparamagnetic iron oxide nanoparticles (SPIONs) with these cellular structures in the presence of a magnetic field gradient. A one-cell-type–based blood-brain barrier model was used to investigate the attachment and uptake mechanisms of differentially charged magnetic hybrid materials. Inhibition of clathrin-dependent endocytosis and F-actin depolymerization led to a dramatic reduction of cellular uptake. Furthermore, the subsequent transportation of SPIONs through the barrier and the ability to detect these particles was of interest. Negatively charged SPIONs could be detected behind the barrier as well as in a reporter cell line. These observations could be confirmed with a two-cell-type–based blood-placenta barrier model. While positively charged SPIONs heavily interact with the apical cell layer, neutrally charged SPIONs showed a retarded interaction behavior. Behind the blood-placenta barrier, negatively charged SPIONs could be clearly detected. Finally, the transfer of the in vitro blood-placenta model in a microfluidic biochip allows the integration of shear stress into the system. Even without particle accumulation in a magnetic field gradient, the negatively charged SPIONs were detectable behind the barrier. In conclusion, in vitro blood-organ barrier models allow the broad investigation of magnetic hybrid materials with regard to biocompatibility, cell interaction, and transfer through cell layers on their way to biomedical application.

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Evaluation of Position RMS Error from Magnetic Field Gradient for Surgical EM Tracking Systems

2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) ◽

10.1109/i2mtc43012.2020.9128837 ◽

2020 ◽

Cited By ~ 1

Author(s):

Mattia Alessandro Ragolia ◽

Filippo Attivissimo ◽

Attilio Di Nisio ◽

Anna Maria Lucia Lanzolla

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Magnetic Field Gradient ◽

Tracking Systems ◽

Rms Error

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Two-dimensional EPR imaging with the rapid scan and rotated magnetic field gradient

Journal of Magnetic Resonance ◽

10.1016/j.jmr.2014.09.022 ◽

2014 ◽

Vol 248 ◽

pp. 126-130 ◽

Cited By ~ 9

Author(s):

T. Czechowski ◽

W. Chlewicki ◽

M. Baranowski ◽

K. Jurga ◽

P. Szczepanik ◽

...

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Magnetic Field Gradient ◽

Two Dimensional ◽

Rapid Scan

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4697149 NMR flow imaging using a composite excitation field and magnetic field gradient sequence

Magnetic Resonance Imaging ◽

10.1016/0730-725x(88)90463-8 ◽

1988 ◽

Vol 6 (2) ◽

pp. III

Author(s):

Paul R Moran

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Magnetic Field Gradient ◽

Flow Imaging ◽

Excitation Field

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Direct mechanical stimulation of tip links in hair cells through DNA tethers

eLife ◽

10.7554/elife.16041 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 15

Author(s):

Aakash Basu ◽

Samuel Lagier ◽

Maria Vologodskaia ◽

Brian A Fabella ◽

AJ Hudspeth

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Mechanical Stimulation ◽

Hair Cells ◽

Magnetic Field Gradient ◽

Hair Bundle ◽

Mechanical Forces ◽

Mechanoelectrical Transduction ◽

Superparamagnetic Beads ◽

Stimulation Of

Mechanoelectrical transduction by hair cells commences with hair-bundle deflection, which is postulated to tense filamentous tip links connected to transduction channels. Because direct mechanical stimulation of tip links has not been experimentally possible, this hypothesis has not been tested. We have engineered DNA tethers that link superparamagnetic beads to tip links and exert mechanical forces on the links when exposed to a magnetic-field gradient. By pulling directly on tip links of the bullfrog's sacculus we have evoked transduction currents from hair cells, confirming the hypothesis that tension in the tip links opens transduction channels. This demonstration of direct mechanical access to tip links additionally lays a foundation for experiments probing the mechanics of individual channels.

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Remote manipulation of magnetic nanoparticles using magnetic field gradient to promote cancer cell death

10.1101/317115 ◽

2018 ◽

Author(s):

Mahendran Subramanian ◽

Arkadiusz Miaskowski ◽

Stuart Iain Jenkins ◽

Jenson Lim ◽

Jon Dobson

Keyword(s):

Magnetic Field ◽

Magnetic Nanoparticles ◽

Field Gradient ◽

Biomedical Applications ◽

Magnetic Field Gradient ◽

Field Source ◽

Remote Manipulation ◽

Cancer Cell Death ◽

The Magnetic Field

AbstractThe manipulation of magnetic nanoparticles (MNPs) using an external magnetic field, has been demonstrated to be useful in various biomedical applications. Some techniques have evolved utilizing this non-invasive external stimulus but the scientific community widely adopts few, and there is an excellent potential for more novel methods. The primary focus of this study is on understanding the manipulation of MNPs by a time-varying static magnetic field and how this can be used, at different frequencies and displacement, to manipulate cellular function. Here we explore, using numerical modeling, the physical mechanism which underlies this kind of manipulation, and we discuss potential improvements which would enhance such manipulation with its use in biomedical applications, i.e., increasing the MNP response by improving the field parameters. From our observations and other related studies, we infer that such manipulation depends mostly on the magnetic field gradient, the magnetic susceptibility and size of the MNPs, the magnet array oscillating frequency, the viscosity of the medium surrounding MNPs, and the distance between the magnetic field source and the MNPs. Additionally, we demonstrate cytotoxicity in neuroblastoma (SH-SY5Y) and hepatocellular carcinoma (HepG2) cells in vitro. This was induced by incubation with MNPs, followed by exposure to a magnetic field gradient, physically oscillating at various frequencies and displacement amplitudes. Even though this technique reliably produces MNP endocytosis and/or cytotoxicity, a better biophysical understanding is required to develop the mechanism used for this precision manipulation of MNPs, in vitro.

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