Nanomaterials as Contrast Agents for MRI

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Biology and Medicines".

Deadline for manuscript submissions: closed (31 May 2023) | Viewed by 4739

Special Issue Editor

Physics Department, Università degli Studi di Milano and INSTM Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali - Milano Unit, Via Celoria 16, 20133 Milan, Italy
Interests: magnetic multifunctional nanoparticles; molecular magnets; low-dimensional magnetic clusters; magnetic highly-sensitive biosensors; nuclear magnetic resonance; magnetic resonance imaging; applications of NMR in cultural heritage; magnetometry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In medical imaging, the continuous quest to improve diagnostic performance and optimize treatment strategies is driving enormous progress and changes in magnetic resonance imaging (MRI). In this respect, the use of magnetic contrast agents (CA) has allowed an increase in the sensitivity and specificity of MRI since the beginning. The recent developments in materials science and nanotechnology and the peculiar properties of nanomaterials have been encouraging the use of magnetic nanostructures as promising alternatives to current commercial contrast agents. 

The Special Issue seeks to focus on novelties in the synthesis procedures, characterization of magnetic nanomaterials and theoretical interpretations of their magnetic properties, all these being crucial building blocks for achieving valuable nanomaterials for MRI. Therefore, I cordially invite front-line researchers to submit original articles and reviews in order to present the state of the art in the abovementioned research field. 

Dr. Paolo Arosio
Guest Editor

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Keywords

  • magnetic resonance imaging
  • MRI contrast agents
  • magnetic nanostructures
  • paramagnetic contrast agents
  • superparamagnetic contrast agents
  • magnetic materials
  • magnetic multifunctional nanoparticles
  • nuclear magnetic resonance
  • medical imaging

Published Papers (4 papers)

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Research

23 pages, 7167 KiB  
Article
Dual Labeling of Primary Cells with Fluorescent Gadolinium Oxide Nanoparticles
by Nadine Brune, Benedikt Mues, Eva Miriam Buhl, Kai-Wolfgang Hintzen, Stefan Jockenhoevel, Christian G. Cornelissen, Ioana Slabu and Anja Lena Thiebes
Nanomaterials 2023, 13(12), 1869; https://doi.org/10.3390/nano13121869 - 16 Jun 2023
Viewed by 1136
Abstract
The interest in mesenchymal stromal cells as a therapy option is increasing rapidly. To improve their implementation, location, and distribution, the properties of these must be investigated. Therefore, cells can be labeled with nanoparticles as a dual contrast agent for fluorescence and magnetic [...] Read more.
The interest in mesenchymal stromal cells as a therapy option is increasing rapidly. To improve their implementation, location, and distribution, the properties of these must be investigated. Therefore, cells can be labeled with nanoparticles as a dual contrast agent for fluorescence and magnetic resonance imaging (MRI). In this study, a more efficient protocol for an easy synthesis of rose bengal–dextran-coated gadolinium oxide (Gd2O3-dex-RB) nanoparticles within only 4 h was established. Nanoparticles were characterized by zeta potential measurements, photometric measurements, fluorescence and transmission electron microscopy, and MRI. In vitro cell experiments with SK-MEL-28 and primary adipose-derived mesenchymal stromal cells (ASC), nanoparticle internalization, fluorescence and MRI properties, and cell proliferation were performed. The synthesis of Gd2O3-dex-RB nanoparticles was successful, and they were proven to show adequate signaling in fluorescence microscopy and MRI. Nanoparticles were internalized into SK-MEL-28 and ASC via endocytosis. Labeled cells showed sufficient fluorescence and MRI signal. Labeling concentrations of up to 4 mM and 8 mM for ASC and SK-MEL-28, respectively, did not interfere with cell viability and proliferation. Gd2O3-dex-RB nanoparticles are a feasible contrast agent to track cells via fluorescence microscopy and MRI. Fluorescence microscopy is a suitable method to track cells in in vitro experiments with smaller samples. Full article
(This article belongs to the Special Issue Nanomaterials as Contrast Agents for MRI)
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13 pages, 2770 KiB  
Article
1H-NMR Relaxation of Ferrite Core-Shell Nanoparticles: Evaluation of the Coating Effect
by Francesca Brero, Paolo Arosio, Martin Albino, Davide Cicolari, Margherita Porru, Martina Basini, Manuel Mariani, Claudia Innocenti, Claudio Sangregorio, Francesco Orsini and Alessandro Lascialfari
Nanomaterials 2023, 13(5), 804; https://doi.org/10.3390/nano13050804 - 22 Feb 2023
Cited by 2 | Viewed by 1192
Abstract
We investigated the effect of different organic coatings on the 1H-NMR relaxation properties of ultra-small iron-oxide-based magnetic nanoparticles. The first set of nanoparticles, with a magnetic core diameter ds1 = 4.4 ± 0.7 nm, was coated with polyacrylic acid (PAA) [...] Read more.
We investigated the effect of different organic coatings on the 1H-NMR relaxation properties of ultra-small iron-oxide-based magnetic nanoparticles. The first set of nanoparticles, with a magnetic core diameter ds1 = 4.4 ± 0.7 nm, was coated with polyacrylic acid (PAA) and dimercaptosuccinic acid (DMSA), while the second set, ds2 = 8.9 ± 0.9 nm, was coated with aminopropylphosphonic acid (APPA) and DMSA. At fixed core diameters but different coatings, magnetization measurements revealed a similar behavior as a function of temperature and field. On the other hand, the 1H-NMR longitudinal r1 nuclear relaxivity in the frequency range ν = 10 kHz ÷ 300 MHz displayed, for the smallest particles (diameter ds1), an intensity and a frequency behavior dependent on the kind of coating, thus indicating different electronic spin dynamics. Conversely, no differences were found in the r1 relaxivity of the biggest particles (ds2) when the coating was changed. It is concluded that, when the surface to volume ratio, i.e., the surface to bulk spins ratio, increases (smallest nanoparticles), the spin dynamics change significantly, possibly due to the contribution of surface spin dynamics/topology. Full article
(This article belongs to the Special Issue Nanomaterials as Contrast Agents for MRI)
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19 pages, 4457 KiB  
Article
Effect of Europium Substitution on the Structural, Magnetic and Relaxivity Properties of Mn-Zn Ferrite Nanoparticles: A Dual-Mode MRI Contrast-Agent Candidate
by Hamidreza Saeidi, Morteza Mozaffari, Serhat Ilbey, Silvio Dutz, Diana Zahn, Gholamhassan Azimi and Michael Bock
Nanomaterials 2023, 13(2), 331; https://doi.org/10.3390/nano13020331 - 12 Jan 2023
Cited by 7 | Viewed by 1492
Abstract
Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal [...] Read more.
Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal stability and sufficient biocompatibility. In this work, we present a detailed description of the synthesis and the characterizations of europium-substituted Mn–Zn ferrite (Mn0.6Zn0.4EuxFe2−xO4, x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.15, herein named MZF for x = 0.00 and EuMZF for others). MNPs were synthesized by the coprecipitation method and subsequent hydrothermal treatment, coated with citric acid (CA) or pluronic F127 (PF-127) and finally characterized by X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP), Vibrating Sample Magnetometry (VSM), Fourier-Transform Infrared (FTIR), Dynamic Light Scattering (DLS) and MRI Relaxometry at 3T methods. The XRD studies revealed that all main diffraction peaks are matched with the spinel structure very well, so they are nearly single phase. Furthermore, XRD study showed that, although there are no significant changes in lattice constants, crystallite sizes are affected by europium substitution significantly. Room-temperature magnetometry showed that, in addition to coercivity, both saturation and remnant magnetizations decrease with increasing europium substitution and coating with pluronic F127. FTIR study confirmed the presence of citric acid and poloxamer (pluronic F127) coatings on the surface of the nanoparticles. Relaxometry measurements illustrated that, although the europium-free sample is an excellent negative contrast agent with a high r2 relaxivity, it does not show a positive contrast enhancement as the concentration of nanoparticles increases. By increasing the europium to x = 0.15, r1 relaxivity increased significantly. On the contrary, europium substitution decreased r2 relaxivity due to a reduction in saturation magnetization. The ratio of r2/r1 decreased from 152 for the europium-free sample to 11.2 for x = 0.15, which indicates that Mn0.6Zn0.4Eu0.15Fe1.85O4 is a suitable candidate for dual-mode MRI contrast agent potentially. The samples with citric acid coating had higher r1 and lower r2 relaxivities than those of pluronic F127-coated samples. Full article
(This article belongs to the Special Issue Nanomaterials as Contrast Agents for MRI)
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12 pages, 2782 KiB  
Article
Effects of PEG Chain Length on Relaxometric Properties of Iron Oxide Nanoparticles-Based MRI Contrast Agent
by Jianxian Ge, Cang Li, Ning Wang, Ruru Zhang, Mohammad Javad Afshari, Can Chen, Dandan Kou, Dandan Zhou, Ling Wen, Jianfeng Zeng and Mingyuan Gao
Nanomaterials 2022, 12(15), 2673; https://doi.org/10.3390/nano12152673 - 04 Aug 2022
Cited by 5 | Viewed by 1948
Abstract
Iron oxide nanoparticles (IONPs) as magnetic resonance imaging (MRI) contrast agents have received considerable interest due to their superior magnetic properties. To increase the biocompatibility and blood circulation time, polyethylene glycol (PEG) is usually chosen to decorate IONPs. Although the surface effect induced [...] Read more.
Iron oxide nanoparticles (IONPs) as magnetic resonance imaging (MRI) contrast agents have received considerable interest due to their superior magnetic properties. To increase the biocompatibility and blood circulation time, polyethylene glycol (PEG) is usually chosen to decorate IONPs. Although the surface effect induced by the PEGylation has an impact on the relaxometric properties of IONPs and can subsequently affect the imaging results, the occurrence of particle aggregation has troubled researchers to deeply explore this correlation. To shed light on this relationship, three diphosphonate PEGs with molecular weights of 1000, 2000, and 5000 Da were used to replace the hydrophobic oleate ligands of 3.6 nm and 10.9 nm IONPs. Then, the contrast enhancement properties of the resultant “aggregation-free” nanoparticles were carefully evaluated. Moreover, related theories were adopted to predict certain properties of IONPs and to compare with the experimental data, as well as obtain profound knowledge about the impacts of the PEG chain length on transverse relaxivity (r2) and longitudinal relaxivity (r1). It was found that r2 and the saturated magnetization of the IONPs, independent of particle size, was closely related to the chain length of PEG. The results unveiled the correlation between the chain length of the coated PEG and the relaxometric properties of IONPs, providing valuable information which might hold great promise in designing optimized, high-performance IONPs for MRI-related applications. Full article
(This article belongs to the Special Issue Nanomaterials as Contrast Agents for MRI)
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