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Synthesis of nanostructured and hierarchical materials for bio-applications
KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.ORCID iD: 0000-0002-1679-1316
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In recent years, nanostructured materials incorporated with inorganic particles and polymers have attracted attention for simultaneous multifunctional biomedical applications. This thesis summarized three works, which are preparation of mesoporous silica coated superparamagnetic iron oxide (Fe3O4@mSiO2) nanoparticles (NPs) as magnetic resonance imaging T2 contrast agents, polymer grafted Fe3O4@mSiO2 NPs response to temperature change, synthesis and biocompatibility evaluation of high aspect ratio (AR) gold nanorods.

Monodisperse Fe3O4@mSiO2 NPs have been prepared through a sol-gel process. The coating thickness and particle sizes can be precisely controlled by varying the synthesis parameters. Impact of surface coatings on magnetometric and relaxometric properties of Fe3O4 NPs is studied. The efficiency of these contrast agents, evaluated by MR relaxivities ratio (r2/r1), is much higher than that of the commercial ones. This coating-thickness dependent relaxation behavior is explained due to the effects of mSiO2 coatings on water exclusion.

Multifunctional core-shell composite NPs have been developed by growing thermo-sensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) on Fe3O4@mSiO2 NPs through free radical polymerization. Their phase transition behavior is studied, and their lower critical solution temperature (LCST) can be subtly tuned from ca. 34 to ca. 42 °C, suitable for further in vivo applications.

A seedless surfactant-mediated protocol has been applied for synthesis of high AR gold nanorods with the additive of HNO3. A growth mechanism based on the effect of nitrate ions on surfactant micelle elongation and Ostwald ripening process is proposed. The biocompatibility of high AR nanorods was evaluated on primary human monocyte derived dendritic cells (MDDCs). Their minor effects on viability and immune regulatory markers support further development for medical applications.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2011. , x, 54 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2011:4
Keyword [en]
Fe3O4, mSiO2, core-shell, MRI, multifunctional, PNIPAAm, LCST, gold, nanorod, nitric acid, AR, MDDC, biocompatibility, immunomodulation
National Category
Materials Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-35518ISBN: 978-91-7415-903-5 (print)OAI: oai:DiVA.org:kth-35518DiVA: diva2:428932
Presentation
2011-05-30, Sal C2, Isafjordsgatan 22, KTH, Stockholm, 14:00 (English)
Opponent
Supervisors
Note
QC 20110701Available from: 2011-07-01 Created: 2011-07-01 Last updated: 2011-09-29Bibliographically approved
List of papers
1. Synthesis of high aspect ratio gold nanorods and their effects on human antigen presenting dendritic cells
Open this publication in new window or tab >>Synthesis of high aspect ratio gold nanorods and their effects on human antigen presenting dendritic cells
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2011 (English)In: International Journal Of Nanotechnology, ISSN 1475-7435, Vol. 8, no 8-9, 631-652 p.Article in journal (Refereed) Published
Abstract [en]

High aspect ratio (AR) gold nanorods (NRs) attract great interest for biomedical applications due to their novel physicochemical properties. Here, we report a facile method for preparation of high AR gold NRs through a seedless surfactant-mediated protocol with the additive of nitric acid. High-resolution transmission electron microscopy studies showed that the concentration of nitric acid has great effects on the crystal structures of the initially formed nuclei and consequently the growth of gold NRs. A mechanism based on the effect of nitrate ions on surfactant micelle elongation and Ostwald ripening process is proposed for the growth of high AR gold NRs. The biocompatibility of high AR NRs was evaluated on primary human monocyte derived dendritic cells (MDDCs), and compared with that of spherical gold nanoparticles (NPs) and low AR NRs. Low AR (similar to 4.5) gold NRs induced considerable cell death due to CTAB, while spherical gold NPs (7 nm) and high AR (similar to 21) gold NRs showed no or minor effects on viability and immune regulatory markers, which supports the further development of high AR gold NRs for medical applications.

Keyword
gold nanorod, non-seeded, nitric acid, high aspect ratio, biocompatibility, dendritic cells, immunomodulatory effects
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-35502 (URN)10.1504/IJNT.2011.041435 (DOI)000295368600003 ()2-s2.0-79960812642 (Scopus ID)
Note
QC 20111028 Uppdaterad från Submitted till PublishedAvailable from: 2011-07-01 Created: 2011-07-01 Last updated: 2012-06-05Bibliographically approved
2. Multifunctional core-shell nanoparticles: superparamagnetic, mesoporous, and thermosensitive
Open this publication in new window or tab >>Multifunctional core-shell nanoparticles: superparamagnetic, mesoporous, and thermosensitive
2011 (English)In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 13, no 11, 6157-6167 p.Article in journal (Refereed) Published
Abstract [en]

Multifunctional core-shell composite nanoparticles (NPs) have been developed by the combination of three functionalities into one entity, which is composed of a single Fe3O4 NP as the magnetic core, mesoporous silica (mSiO2) with cavities as the sandwiched layer, and thermosensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) copolymer as the outer shell. The mSiO2-coated Fe3O4 NPs (Fe3O4@mSiO2) are monodisperse and the particle sizes were varied from 25 to 95 nm by precisely controlling the thickness of mSiO2-coating layer. The P(NIPAAm-co-AAm) were then grown onto surface-initiator-modified Fe3O4@mSiO2 NPs through free radical polymerization. These core-shell composite NPs (designated as Fe3O4@mSiO2@P(NIPAAm-co-AAm)) were found to be superparamagnetic with high r2 relaxivity. To manipulate the phase transition behavior of these thermosensitive polymer-coated NPs for future in vivo applications, the characteristic lower critical solution temperature (LCST) was subtly tuned by adjusting the composition of the monomers to be around the human body temperature (i.e. 37 °C), from ca. 34 to ca. 42 °C. The thermal response of the core-shell composite NPs to the external magnetic field was also demonstrated. Owing to their multiple functionality characteristics, these porous superparamagnetic and thermosensitive NPs may prove valuable for simultaneous magnetic resonance imaging (MRI), temperature-controlled drug release, and temperature-programed magnetic targeting and separation applications.

Keyword
multifunctional, iron oxide, mesoporous silica, PNIPAAm, core-shell, LCST
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-35505 (URN)10.1007/s11051-011-0272-8 (DOI)000297351600063 ()2-s2.0-84857035953 (Scopus ID)
Note
QC 20110701. QC 20120209Available from: 2011-07-01 Created: 2011-07-01 Last updated: 2017-12-11Bibliographically approved
3. Efficient internalization of silica-coated iron oxide nanoparticles of different sizes by primary human macrophages and dendritic cells
Open this publication in new window or tab >>Efficient internalization of silica-coated iron oxide nanoparticles of different sizes by primary human macrophages and dendritic cells
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2011 (English)In: Toxicology and Applied Pharmacology, ISSN 0041-008X, E-ISSN 1096-0333, Vol. 253, no 2, 81-93 p.Article in journal (Refereed) Published
Abstract [en]

Engineered nanoparticles are being considered for a wide range of biomedical applications, from magnetic resonance imaging to "smart" drug delivery systems. The development of novel nanomaterials for biomedical applications must be accompanied by careful scrutiny of their biocompatibility. In this regard, particular attention should be paid to the possible interactions between nanoparticles and cells of the immune system, our primary defense system against foreign invasion. On the other hand, labeling of immune cells serves as an ideal tool for visualization, diagnosis or treatment of inflammatory processes, which requires the efficient internalization of the nanoparticles into the cells of interest. Here, we compare novel monodispersed silica-coated iron oxide nanoparticles with commercially available dextran-coated iron oxide nanoparticles. The silica-coated iron oxide nanoparticles displayed excellent magnetic properties. Furthermore, they were nontoxic to primary human monocyte-derived macrophages at all doses tested whereas dose-dependent toxicity of the smaller silica-coated nanoparticles (30 nm and 50 nm) was observed for primary monocyte-derived dendritic cells, but not for the similarly small dextran-coated iron oxide nanoparticles. No macrophage or dendritic cell secretion of pro-inflammatory cytokines was observed upon administration of nanoparticles. The silica-coated iron oxide nanoparticles were taken up to a significantly higher degree when compared to the dextran-coated nanoparticles, irrespective of size. Cellular internalization of the silica-coated nanoparticles was through an active, actin cytoskeleton-dependent process. We conclude that these novel silica-coated iron oxide nanoparticles are promising materials for medical imaging, cell tracking and other biomedical applications. (C) 2011 Elsevier Inc. All rights reserved.

Keyword
Superparamagnetic nanoparticles, Surface coating, Biocompatibility, Cytokine secretion, Macrophages, Dendritic cells
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-35507 (URN)10.1016/j.taap.2011.03.011 (DOI)000290822500001 ()2-s2.0-79955636194 (Scopus ID)
Note
QC 20110701Available from: 2011-07-01 Created: 2011-07-01 Last updated: 2017-12-11Bibliographically approved

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