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Uniform mesoporous silica coated iron oxide nanoparticles as a highly efficient, nontoxic MRI T2 contrast agent with tunable proton relaxivities
KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.ORCID iD: 0000-0002-1679-1316
KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
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2012 (English)In: Contrast Media & Molecular Imaging, ISSN 1555-4309, E-ISSN 1555-4317, Vol. 7, no 5, p. 460-468Article in journal (Refereed) Published
Abstract [en]

Monodisperse mesoporous silica (mSiO2) coated superparamagnetic iron oxide (Fe3O4@mSiO2) nanoparticles (NPs) have been developed as a potential magnetic resonance imaging (MRI) T2 contrast agent. To evaluate the effect of surface coating on MRI contrast efficiency, we examined the proton relaxivities of Fe3O4@mSiO2 NPs with different coating thicknesses. It was found that the mSiO2 coating has a significant impact on the efficiency of Fe3O4 NPs for MRI contrast enhancement. The efficiency increases with the thickness of mSiO2 coating and is much higher than that of the commercial contrast agents. Nuclear magnetic resonance (NMR) relaxometry of Fe3O4@mSiO2 further revealed that mSiO2 coating is partially permeable to water molecules and therefore induces the decrease of longitudinal relaxivity, r1. Biocompatibility evaluation of various sized (ca. 3595 nm) Fe3O4@mSiO2 NPs was tested on OC-k3 cells and the result showed that these particles have no negative impact on cell viability. The enhanced MRI efficiency of Fe3O4@mSiO2 highlights these coreshell particles as highly efficient T2 contrast agents with high biocompatibility.

Place, publisher, year, edition, pages
2012. Vol. 7, no 5, p. 460-468
Keywords [en]
MRI, contrast agent, superparamagnetic, iron oxide, mesoporous silica, coating thickness, tunable relaxivity, biocompatibility
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-96493DOI: 10.1002/cmmi.1473ISI: 000306671100004PubMedID: 22821880Scopus ID: 2-s2.0-84864143614OAI: oai:DiVA.org:kth-96493DiVA, id: diva2:530902
Funder
EU, European Research Council, NMP4-CT-2006-026556 NMP4-SL-2008-214281
Note

QC 20120824

Available from: 2012-06-05 Created: 2012-06-05 Last updated: 2024-03-18Bibliographically approved
In thesis
1. Chemically Synthesized Nano-Structured Materials for Biomedical and Photonic Applications
Open this publication in new window or tab >>Chemically Synthesized Nano-Structured Materials for Biomedical and Photonic Applications
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanostructured materials have attracted a broad interest for applications in scientific and engineering fields due to their extraordinary properties stemming from the nanoscale dimensions. This dissertation presents the development of nanomaterials used for different applications, namely biomedicine and dye lasing.

Various inorganic nanoparticles have been developed as contrast agents for non-invasive medical imaging, such as magnetic resonance imaging (MRI) and X-ray computed tomography (CT), owing to their unique properties for efficient contrasting effect. Superparamagnetic iron oxide nanoparticles (SPIONs) are synthesized by thermo-decomposition method and phase-transferred to be hydrophilic used as MRI T2 (negative) contrast agents. Effects of surface modification of SPIONs by mesoporous silica (mSiO2) coating have been examined on the magnetic relaxivities. These contrast agents (Fe3O4@mSiO2) were found to have a coating-thickness dependent relaxation behavior and exhibit much higher contrast efficiency than that for the commercial ones. By growing thermo-sensitive poly(N-isopropylacrylamide -co-acrylamide) (P(NIPAAm-co-AAm)) as the outermost layer on Fe3O4@mSiO2 through free radical polymerization, a multifunctional core-shell nano-composite has been built up. Responding to the temperature change, these particles demonstrate phase transition behavior and were used for thermo-triggered magnetic separation. Their lower critical solution temperature (LCST) can be subtly tuned from ca. 34 to ca. 42 ˚C, suitable for further in vivo applications. An all-in-one contrast agent for MRI, CT and fluorescence imaging has been synthesized by depositing gadolinium oxide carbonate hydrate [Gd2O(CO3)2·H2O] shell on mSiO2-coated gold nanorod (Au NR), and then the particles were grafted with antibiofouling copolymer which can further link with the fluorescent dye. It shows both a higher CT and MRI contrast than the clinical iodine and gadolinium chelate contrast agent, respectively. Apart from the imaging application, owing to the morphology of Au NR, the particle has a plasmonic property of absorbing near-infrared (NIR) irradiation and suitable for future photothermal therapy. Cytotoxicity and biocompatibility of aforementioned nanoparticles have been evaluated and minor negative effects were found, which support their further development for medical applications.

Gold nanoparticles embedded in the optical gain material, water solution of Rhodamine 6G (Rh6G) in particular, used in dye lasers can both increase and damp the dye fluorescence, thus, changing the laser output intensity. The studies of size effect and coating of gold nanoparticles on photostability of the gain media reveal that small sized (ca. 5.5 nm) gold nanoparticles are found detrimental to the photostability, while for the larger ones (ca. 25 nm) fluorescence enhancement rather than quenching is likely to occur. And a noticeable improvement of the photostability for the gain material is achieved when gold is coated with SiO2.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. p. xii, 45
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2012:12
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-96261 (URN)
Public defence
2012-06-12, Sal/Hall C2, Electrum, KTH-ICT, Isafjordsgatan 26, Kista, 10:00 (English)
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Supervisors
Note
QC 20120605Available from: 2012-06-05 Created: 2012-05-31 Last updated: 2022-06-24Bibliographically approved

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Ye, FeiToprak, MuhammetMuhammed, Mamoun

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