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Spatially resolved magneto-relaxation of in-vitro magnetic nanoparticles using atomic magnetometry

English title Spatially resolved magneto-relaxation of in-vitro magnetic nanoparticles using atomic magnetometry
Applicant Weis Antoine
Number 144257
Funding scheme Sinergia
Research institution Département de Physique Université de Fribourg
Institution of higher education University of Fribourg - FR
Main discipline Other disciplines of Physics
Start/End 01.09.2012 - 31.08.2013
Approved amount 268'377.00
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All Disciplines (6)

Discipline
Other disciplines of Physics
Material Sciences
Technical Physics
Organic Chemistry
Inorganic Chemistry
Biomedical Engineering

Keywords (5)

imaging techniques; atomic magnetometers; SPION; magnetic nanoparticles; spin diffusion

Lay Summary (English)

Lead
Lay summary

Magnetic nanoparticles (MNPs) have superparamagnetic properties that can be detected by high sensitivity magnetometers which record the decay of the magnetic field they produce following their magnetization by an externally applied magnetic field pulse. The relaxation time of the MNPs’ magnetization has a strong dependence on the MNPs’ surrounding. The use of functionalized MNPs that preferentially attach to defined biological entities (magnetic tagging), such as cancer cells or specific organs thus allows the specific mapping of those entities.

After magnetizing the particles by exposing them to a strong external magnetic field, the relaxation of the sample's magnetization is measured by recording the time-dependence of the magnetic field that they generate by one (or an array of) magnetometers. The technique is known as magneto-relaxometry (MRX). The state of the art in MRX measurements is currently defined by SQUID magnetometers that have to be operated at cryogenic temperatures. The use of room-temperature atomic magnetometers promises several advantages that will increase the flexibility of an MRX apparatus and will thus significantly simplify the wider spreading of this technique.

In the past two years we have developed a technique for detecting magneto-relaxation signals from magnetic nanoparticles (MNP) by means of atomic magnetometers in a second-order gradiometer configuration. The three partners of our interdisciplinary collaboration have joined their complementary expertise (magnetometry by partner FRAP, sample preparation by partner AMI at Adolph-Merkle Institute, and source localization by solving the inverse problem by partner 3 (BMZ, now at Paul Scherrer Institute, PSI) to achieve first encouraging results: we have shown that atomic magnetometers have the sensitivity required to detect MRX signals from dilute samples of matrix-embedded nanoparticles, thereby breaking the monopoly position held so far by SQUID detectors for MRX measurements.

In the granted one-year extension of the project, we want to consolidate and further develop the methods, techniques and algorithms. Partner FRAP will record the spatial magnetic field distribution of structured distributions of in vitro MNPs (prepared by partner AMI) embedded in bulk matrices or on surfaces by deploying arrays of atomic magnetometers for large samples. We will modify the geometry, sensor spacing and detection method of our current set-up. Partner BMZ will collaborate with partner FRAP in the design of the new system and will be responsible for solving the inverse problem of relating the measured magnetic field maps to source distributions. In parallel to the large scale system, we will optimize our original “magnetic field mapping camera” for the imaging of small (cm-size) samples backed by numerical simulations.

The project is coordinated by Prof. Antoine Weis (University of Fribourg, partner FRAP), whose laboratories hosts the experimental installations for the MRX measurements. Partner AMI (Prof. A. Fink) will focus on the synthesis and characterization of monodisperse single superparamagnetic iron oxide nanoparti-cles (SPIONs) as well as magnetic beads whose iron oxide content, and with that the magnetic response, can be tuned during the synthesis. Derivatization to enhance colloidal stability, increased circulation time and target cell surfaces will be key issues. Dr. Bison's team (partner BMZ) will work on various aspects of multi-sensor magnetometry and source reconstruction.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Non-scanning magnetic field imaging with laser-pumped atomic magnetometer
Lebedev Victor, Dolgovskiy Vladimir, Michen Benjamin, Fink Alke, Bison Georg, Weis Antoine (2013), Non-scanning magnetic field imaging with laser-pumped atomic magnetometer, in Biomedizinische Technik / Biomedical Engineering, 58(SI-1), 663-664.

Collaboration

Group / person Country
Types of collaboration
IPHT-Jena Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
University Lund Sweden (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
University Fribourg - Chemistry Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Modern Problems of Laser Physics Individual talk 25.08.2013 Novosibirsk, Russia Weis Antoine;
2013 IEEE—UFFC Joint Symposium Individual talk 21.07.2013 Prague, Czech Republic Weis Antoine;
Kolloquium Individual talk 02.07.2013 Uni Stuttgart, Germany Weis Antoine;
ECAMP-2013 Individual talk 24.06.2013 Aarhus, Denmark Weis Antoine;
ESMI Annual Meeting 2013 Talk given at a conference 27.05.2013 Rimini, Italy Michen Benjamin;
Swiss Working Group for Surface and Interface Science (SAOG) Talk given at a conference 25.01.2013 Fribourg, Switzerland Michen Benjamin;


Associated projects

Number Title Start Funding scheme
172626 Highly accurate vector gradiometers for a next-generation neutron EDM experiment 01.08.2017 Project funding
130414 Spatially resolved magneto-relaxation of in-vitro magnetic nanoparticles using atomic magnetometry 01.09.2010 Sinergia
160128 A magnetic field imaging camera for recording the magnetorelaxation of magnetic nanoparticles 01.10.2015 Project funding
162988 Magnetic particle imaging (MPI) with atomic magnetometers 01.10.2015 Project funding
149542 A high-sensitivity AC-susceptometer based on atomic magnetometry 01.10.2013 Project funding
163990 Magnetic nanoparticle characterization by AC-Susceptometry (ACS) and Magnetic Particle Spectroscopy (MPS) 01.01.2016 R'EQUIP
113641 Développement d'un magnétomètre optique pour la cardiographie foetale 01.10.2006 Project funding
119820 Optical magnetometry for a new neutron EDM experiment 01.04.2008 Project funding
130480 Optical magnetometry for a new neutron EDM experiment 01.04.2010 Project funding
126104 Smart vesicles for drug delivery 01.01.2010 NRP 62 Smart Materials

Abstract

Magnetic nanoparticles (MNPs) have superparamagnetic properties that can be detected byhigh sensitivity magnetometers which record the decay of the magnetic ¯eld they produce fol-lowing their magnetization by an externally applied magnetic ¯eld pulse. The relaxation timeof the MNP's magnetization has a strong dependence on the MNP's surrounding. The useof functionalized MNPs that preferentially attach to de¯ned biological entities (magnetic tag-ging), such as cancer cells or speci¯c organs thus allows the speci¯c mapping of those entities.After magnetizing the particles by exposing them to a strong external magnetic ¯eld, the re-laxation of the sample's magnetization is measured by recording the time-dependence of themagnetic ¯eld that they generate by one (or an array of) magnetometers. The technique isknown as magneto-relaxometry (MRX). The state of the art in MRX measurements is de¯nedby SQUID magnetometers that have to be operated at cryogenic temperatures. The use of room-temperature atomic magnetometers promises several advantages that will increase the °exibilityof an MRX apparatus and will thus signi¯cantly simplify the wider spreading of this technique.In the ongoing (two-year) ¯rst phase of this Sinergia project we have developed a tech-nique for detecting magneto-relaxation signals from magnetic nanoparticles (MNP) by meansof atomic magnetometers in a second-order gradiometer con¯guration. The three partners ofour interdisciplinary collaboration have joined their complementary expertise (magnetometryby partner FRAP, sample preparation by partner AMI, and source localization by solving theinverse problem by partner BMZ) to achieve ¯rst encouraging results: as anticipated in theoriginal proposal, we could show that atomic magnetometers have the sensitivity required todetect MRX signals from dilute samples of matrix-embedded nanoparticles, thereby breakingthe monopoly position held so far by SQUID detectors for MRX measurements.Here we request a (¯nal) two-year extension of the project, during which we want to extendand consolidate the methods, techniques and algorithms developed during the ¯rst phase. Part-ner FRAP will record the spatial magnetic ¯eld distribution of structured distributions of invitro MNPs (prepared by partner AMI) embedded in bulk matrices or on surfaces by deployingarrays of atomic magnetometers for large (¼300 cm2) sized samples. For this, we will modifythe geometry and sensor spacing of our current 19-magnetometer set-up, going from the current19 channel system on a hexagonal 50 mm spaced grid to a 49 channel system on a square gridwith 32 mm sensor spacing. Partner BMZ will collaborate with partner FRAP in the designof the new system and will be responsible for solving the inverse problem of relating the mea-sured magnetic ¯eld maps to source distributions. In parallel to the large scale system, we willoptimize our original \magnetic ¯eld mapping camera" for the imaging of small (¼ cm2) scalesamples { a prototype of which is being realized during the ongoing phase of the project { bysystematic variations of its operating parameters, backed by numerical simulations.In 2011, Prof. Alke Petri-Fink and her team (former partner FRChem, now partner AMI)have moved to the Adolphe Merkle Institute (AMI) in Fribourg. Partner AMI will focus on thesynthesis and characterization of monodisperse single superparamagnetic iron oxide nanoparti-cles (SPIONs) as well as magnetic beads whose iron oxide content, and with that the magneticresponse, can be tuned during the synthesis. Derivatization to enhance colloidal stability, in-creased circulation time and target cell surfaces will be key issues. The project will culminatein a study of the iron uptake by macrophage cells.The future activities of Dr. Bison's team at PSI (moving from Jena foreseen in April 2012)will be devoted to various aspects of multi-sensor magnetometry, and thereby have a large overlapwith the tasks of the present project. The project continues to be coordinated by Prof. AntoineWeis (Physics Department, University of Fribourg, partner FRAP), whose laboratories hoststhe experimental installations for the MRX measurements.
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