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Chemically Synthesized Nano-Structured Materials for Biomedical and Photonic Applications
KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.ORCID iD: 0000-0002-1679-1316
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. , xii, 45 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2012:12
National Category
Nano Technology
Identifiers
URN: urn:nbn:se:kth:diva-96261OAI: oai:DiVA.org:kth-96261DiVA: diva2:529974
Public defence
2012-06-12, Sal/Hall C2, Electrum, KTH-ICT, Isafjordsgatan 26, Kista, 10:00 (English)
Opponent
Supervisors
Note
QC 20120605Available from: 2012-06-05 Created: 2012-05-31 Last updated: 2012-06-05Bibliographically 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. Uniform mesoporous silica coated iron oxide nanoparticles as a highly efficient, nontoxic MRI T2 contrast agent with tunable proton relaxivities
Open this publication in new window or tab >>Uniform mesoporous silica coated iron oxide nanoparticles as a highly efficient, nontoxic MRI T2 contrast agent with tunable proton relaxivities
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2012 (English)In: Contrast Media & Molecular Imaging, ISSN 1555-4309, E-ISSN 1555-4317, Vol. 7, no 5, 460-468 p.Article 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.

Keyword
MRI, contrast agent, superparamagnetic, iron oxide, mesoporous silica, coating thickness, tunable relaxivity, biocompatibility
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-96493 (URN)10.1002/cmmi.1473 (DOI)000306671100004 ()2-s2.0-84864143614 (Scopus ID)
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: 2017-12-07Bibliographically approved
4. Gold nanorod/mesoporoussilica/gadolinium oxide carbonate hydrate core/shell nanoparticles: A multimodalcontrast agent for MRI, CT and fluorescence imaging
Open this publication in new window or tab >>Gold nanorod/mesoporoussilica/gadolinium oxide carbonate hydrate core/shell nanoparticles: A multimodalcontrast agent for MRI, CT and fluorescence imaging
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2012 (English)Manuscript (preprint) (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-96495 (URN)
Note
QS 2012Available from: 2012-06-05 Created: 2012-06-05 Last updated: 2012-06-05Bibliographically approved
5. 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
6. Polymeric/inorganic multifunctional nanoparticles for simultaneous drug delivery and visualization
Open this publication in new window or tab >>Polymeric/inorganic multifunctional nanoparticles for simultaneous drug delivery and visualization
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2010 (English)In: Materials Research Society Symposium Proceedings, ISSN 0272-9172, E-ISSN 1946-4274, Vol. 1257Article in journal (Refereed) Published
Abstract [en]

Nanoparticles consisting of different biocompatible materials are attracting a lot of interest in the biomedical area as useful tools for drug delivery, photo-therapy and contrast enhancement agents in MRI, fluorescence and confocal microscopy. This work mainly focuses on the synthesis of polymeric/inorganic multifunctional nanoparticles (PIMN) based on biocompatible di-block copolymer poly(L,L-lactide-co-ethylene glycol) (PLLA-PEG) via an emulsion-evaporation method. Besides containing a hydrophobic drug (Indomethacin), these polymeric nanoparticles incorporate different visualization agents such as superparamagnetic iron oxide nanoparticles (SPION) and fluorescent Quantum Dots (QDs) that are used as contrast agents for Magnetic Resonance Imaging (MRI) and fluorescence microscopy together. Gold Nanorods are also incorporated in such nanostructures to allow simultaneous visualization and photodynamic therapy. MRI studies are performed with different loading of SPION into PIMN, showing an enhancement in T2 contrast superior to commercial contrast agents. Core-shell QDs absorption and emission spectra are recorded before and after their loading into PIMN. With these polymeric/inorganic multifunctional nanoparticles, both MRI visualization and confocal fluorescence microscopy studies can be performed. Gold nanorods are also synthesized and incorporated into PIMN without changing their longitudinal absorption peak usable for lased excitation and phototherapy. In-vitro cytotoxicity studies have also been performed to confirm the low cytotoxicity of PIMN for further in-vivo studies.

National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-26782 (URN)10.1557/PROC-1257-O04-03 (DOI)2-s2.0-79951616373 (Scopus ID)
Note
QC 20101202Available from: 2010-11-26 Created: 2010-11-26 Last updated: 2017-12-12Bibliographically approved
7. Fluorescence quenching and photobleaching in Au/Rh6G nanoassemblies: impact of competition between radiative and non-radiative decay
Open this publication in new window or tab >>Fluorescence quenching and photobleaching in Au/Rh6G nanoassemblies: impact of competition between radiative and non-radiative decay
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2011 (English)In: JOURNAL OF THE EUROPEAN OPTICAL SOCIETY-RAPID PUBLICATIONS, ISSN 1990-2573, Vol. 6, 11019- p.Article in journal (Refereed) Published
Abstract [en]

We report the study of fluorescence quenching from nanoassemblies formed by Rhodamine 6G and gold nanoparticles (Au NPs) of 2.6 nm radius. The presence of Au NPs induces long-term degradation of the photostability (photobleaching) of Rhodamine 6G used as a gain medium in a Fabry-Perot laser cavity. We found that the degradation gets profound when the Au NPs concentration is significantly increased. Calculation of the radiative rate and direct time-resolved measurement of the fluorescence decay indicates that both the decrease of radiative decay rate and increase of non-radiative decay rate are responsible for the fluorescence quenching and photostability degradation. An energy transfer from the dye molecules to gold nanoparticles is dominating within small distance between them and suppresses the quantum efficiency of Rhodamine 6G drastically. In a long time scale, the photobleaching rate was slowing down, and the laser output intensity reached a stabilized level which depends on the gold nanoparticles concentration.

Keyword
gold nanoparticles, Rhodamine 6G, fluorescence quenching, photostability
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-34659 (URN)10.2971/jeos.2011.11019 (DOI)000291056100002 ()2-s2.0-84863248410 (Scopus ID)
Note
QC 20110623Available from: 2011-06-23 Created: 2011-06-13 Last updated: 2012-06-05Bibliographically approved
8. Photostability of lasing process from water solution of Rhodamine 6G with gold nanoparticles
Open this publication in new window or tab >>Photostability of lasing process from water solution of Rhodamine 6G with gold nanoparticles
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2012 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 1, 34-36 p.Article in journal (Refereed) Published
Abstract [en]

We report the lasing performance and photobleaching of gain material containing a water solution of Rhodamine 6G dye and gold nanoparticles (NPs). In comparison to a pure dye solution, the investigated material demonstrated both enhancement and quenching of the lasing output, depending on the relative concentration of the gold NPs. Although the presence of NPs with an optimized concentration looks preferable in terms of the lasing output enhancement, such additives deteriorate the operational resource of the gain material; i.e., the photobleaching rate speeds up.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-91140 (URN)10.1364/OL.37.000034 (DOI)000299167100010 ()2-s2.0-84855776748 (Scopus ID)
Note
QC 20120605Available from: 2012-03-08 Created: 2012-03-08 Last updated: 2017-12-07Bibliographically approved
9. Lasing From Water Solution of Rhodamine 6G/Gold Nanoparticles: Impact of SiO2-Coating on Metal Surface
Open this publication in new window or tab >>Lasing From Water Solution of Rhodamine 6G/Gold Nanoparticles: Impact of SiO2-Coating on Metal Surface
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2012 (English)In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 48, no 9, 1220-1226 p.Article in journal (Refereed) Published
Abstract [en]

Gold nanoparticles embedded in an optical gain material, particularly in a water solution of Rhodamine 6G, used in dye lasers can both increase and damp dye flourescence, thus changing the laser output intensity. Simultaneously, such nanoparticles influence the gain material's resistance against photobleaching. In this paper, we report our study on the impact of the SiO2 coating of nanoparticles on the enhancement or quenching and photobleaching of the fluorescence. The investigation demonstrates a noticeable improvement of the gain material's photostability compared to uncoated gold nanoparticles when silicon dioxide coating is implemented.

Keyword
Fluorescence quenching, gold nanoparticles, photostability, Rhodamine 6G, silica coating
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-96499 (URN)10.1109/JQE.2012.2207947 (DOI)000306912800001 ()
Funder
Swedish Research CouncilEU, European Research Council, NMP4-SL-2008-214281
Note

QC 20120827. Updated from submitted to published.

Available from: 2012-06-05 Created: 2012-06-05 Last updated: 2017-12-07Bibliographically approved

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