| 1. |
- Glomm, Wilhelm R., et al.
(författare)
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Europium(III)-cored fluorinated dendrimers at the air-water surface
- 2007
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Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 299:03-jan, s. 186-197
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Tidskriftsartikel (refereegranskat)abstract
- A series of lanthanide (Eu3+) cored fluorinated dendrimers of generations I through 4 (G1-G4) have been studied with respect to their film-forming properties at the air-water surface. All dendrimers studied here formed stable films at the air-water surface. At the air-water surface, the dendrimers are likely to adopt asymmetric funnel-like conformations wherein the lanthanide core is directed towards the water surface and the fluorinated phenyl groups are directed away from the bulk phase. This hypothesis was further tested by addition of an electrolyte (0.01 M MgSO4) to the subphase. The added electrolyte was found to (i) advance the onset of network formation, as well as completion of monolayers, and (ii) increase the collapse pressure. Both features support the asymmetric conformation hypothesis, in that addition of an electrolyte promotes further conformational changes and shields electrostatic repulsion between lanthanide cores, thus allowing for closer packing of the molecules.
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| 2. |
- Bandyopadhyay, Sulalit, et al.
(författare)
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Growing gold nanostructures for shape-selective cellular uptake
- 2018
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Ingår i: Nanoscale Research Letters. - : SpringerOpen. - 1931-7573 .- 1556-276X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- With development in the synthesis of shape- and size-dependent gold (Au) nanostructures (NSs) and their applications in nanomedicine, one of the biggest challenges is to understand the interaction of these shapes with cancer cells. Herein, we study the interaction of Au NSs of five different shapes with glioblastoma-astrocytoma cells. Three different shapes (nanorods, tetrahexahedra, and bipyramids), possessing tunable optical properties, have been synthesized by a single-step seed-mediated growth approach employing binary surfactant mixtures of CTAB and a secondary surfactant By the use of two-step seed-mediated approach, we obtained new NSs, named nanomakura (Makura is a Japanese word used for pillow) which is reported for the first time here. Spherical Au nanoparticles were prepared by the Turkevich method. To study NS-cell interactions, we functionalized the NSs using thiolated PEG followed by 11-Mercaptoundecanoic acid. The influence of shape and concentration of NSs on the cytotoxicity were assessed with a LIVE/DEAD assay in glioblastoma-astrocytoma cells. Furthermore, the time-dependent uptake of nanomakura was studied with TEM. Our results indicate that unlike the other shapes studied here, the nanomakura were taken up both via receptor-mediated endocytosis and macropinocytosis. Thus, from our library of different NSs with similar surface functionality, the shape is found to be an important parameter for cellular uptake.
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| 3. |
- Baumann, Anne, et al.
(författare)
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HAMLET Forms Annular Oligomers When Deposited with Phospholipid Monolayers
- 2012
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 418:1-2, s. 90-102
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Tidskriftsartikel (refereegranskat)abstract
- Recently, the anticancer activity of human a-lactalbumin made lethal to tumor cells (HAMLET) has been linked to its increased membrane affinity in vitro, at neutral pH, and ability to cause leakage relative to the inactive native bovine alpha-lactalbumin (BLA) protein. In this study, atomic force microscopy resolved membrane distortions and annular oligomers (AOs) produced by HAMLET when deposited at neutral pH on mica together with a negatively charged lipid monolayer. BLA, BAMLET (HAMLET's bovine counterpart) and membrane-binding Peptide C, corresponding to BLA residues 75-100, also form AO-like structures under these conditions but at higher subphase concentrations than HAMLET. The N-terminal Peptide A, which binds to membranes at acidic but not at neutral pH, did not form AOs. This suggests a correlation between the capacity of the proteins/peptides to integrate into the membrane at neutral pH as observed by liposome content leakage and circular dichroism experiments and the formation of AOs, albeit at higher concentrations. Formation of AOs, which might be important to HAMLET's tumor toxic action, appears related to the increased tendency of the protein to populate intermediately folded states compared to the native protein, the formation of which is promoted by, but not uniquely dependent on, the oleic acid molecules associated with HAMLET. (C) 2012 Elsevier Ltd. All rights reserved.
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| 4. |
- Kumar, P. Anil, et al.
(författare)
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Superspin glass state and exchange bias in amorphous Fe/Fe-O core/shell nanoparticles
- 2014
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Ingår i: Materials Research Express. - : IOP Publishing. - 2053-1591. ; 1:3
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles of iron and iron oxide are widely explored in several biomedical and technological applications. We report on the magnetic properties of amorphous Fe/Fe-O core/shell nanoparticles compared to those of a reference system with crystalline Fe-O nanoparticles. These nanoparticles are prepared by thermal decomposition of iron precursor, where the amorphous and crystalline nature of core and shell is determined by the choice and concentration of the ligand. The crystalline system exhibits a blocking temperature higher than 300K and negligible exchange bias effect. In contrast, the amorphous systems display large exchange bias, and collective magnetic behavior at low temperatures, with features of magnetic frustration and disorder reminiscent of those observed in spin glass and superspin glass systems. We discuss the origin of the dynamical magnetic behavior of the amorphous particles and study the dependence of the exchange bias field on the cooling field.
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| 5. |
- McDonagh, Birgitte H, et al.
(författare)
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Controlling the self-assembly and optical properties of gold nanoclusters and gold nanoparticles biomineralized with bovine serum albumin
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 5:122, s. 101101-101109
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Tidskriftsartikel (refereegranskat)abstract
- While the size-dependent optical properties of BSA-stabilized gold nanoclusters are well known, the timedependent growth mechanism remains to be described. Herein, we systematically compare two synthesis methods with and without ascorbic acid, and show that tuning of BSA-stabilized gold nanoclusters (AuNCs) of different sizes can be performed without the aid of an extrinsic reducing agent and with good reproducibility. We also show that adding ascorbic acid yields larger BSA-stabilized gold nanoparticles (AuNPs), and that AuNPs can only form above a threshold gold precursor concentration. Using computed tomography, we describe how these biomineralized AuNPs show size-dependent X-ray attenuation. Growth of BSA-stabilized AuNCs and AuNPs, over a range of gold precursor concentrations, was followed with steady-state fluorescence and UV-vis spectroscopy for one week, constituting the first study of its kind. Based on our results, we propose a mechanism for BSA-stabilization of AuNCs and AuNPs that can further aid in selective growth of discrete AuNCs and AuNPs.
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| 6. |
- McDonagh, Birgitte H., et al.
(författare)
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Self-assembly and characterization of transferrin-gold nanoconstructs and their interaction with bio-interfaces
- 2015
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 7:17, s. 8062-8070
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Tidskriftsartikel (refereegranskat)abstract
- Transferrin (Tf) conjugated to gold nanoparticles and clusters combine the protein's site-specific receptor targeting capabilities with the optical properties imparted by the nano-sized gold. We have described two different synthesis protocols, one yielding fluorescent Tf-stabilized gold nanoclusters (AuNCs) and one yielding Tf-stabilized gold nanoparticles that exhibit localized surface plasmon resonance. We demonstrate that the synthetic route employed has a large influence both on the gold nanostructure formed, and also on the structural integrity of the protein. A slight protein unfolding allows stronger interaction with lipids, and was found to significantly perturb lipid monolayers. Interactions between the protein-gold nanostructures and three different cell types were also assessed, indicating that the enhanced membrane affinity may be attributed to intercellular membrane differences.
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| 7. |
- Momtazi, Leva, et al.
(författare)
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Synthesis, characterization, and cellular uptake of magnetic nanocarriers for cancer drug delivery
- 2014
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 433, s. 76-85
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: The absence of targetability is the primary inadequacy of conventional chemotherapy. Targeted drug delivery systems are conceptualized to overcome this challenge. We have designed a targetable magnetic nanocarrier consisting of a superparamagnetic iron oxide (SPIO) core and biocompatible and biodegradable poly(sebacic anhydride)-block-methyl ether poly(ethylene glycol) (PSA-mPEG) polymer shell. The idea is that this type of carriers should facilitate the targeting of cancer cells. Experiments: PSA-mPEG was synthesized with poly-condensation and the in vitro degradation rate of the polymer was monitored by gel permeation chromatography (GPC). The magnetic nanocarriers were fabricated devoid of any surfactants and were capable of carrying high payload of hydrophobic dye. The successful encapsulation of SPIO within the polymer shell was confirmed by TEM. The results we obtained from measuring the size of SPIO loaded in polymeric NPs (SPIO-PNP) by dynamic light scattering (DLS) and iron content measurement of these particles by ICP-MS, indicate that SPIO is the most suitable carrier for cancer drug delivery applications. Findings: Measuring the hydrodynamic radii of SPIO-PNPs by DLS over one month revealed the high stability of these particles at both body and room temperature. We further investigated the cell viability and cellular uptake of SPIO-PNPs in vitro with MDA-MB-231 breast cancer cells. We found that SPIO-PNPs induce negligible toxicity within a concentration range of 12 mu g/ml. The TEM micrographs of thin cross-sectioned MDA-MBA-231 cells showed internalization of SPIO-PNPs within size range of 150-200 nm after 24 h. This study has provided a foundation for eventually loading these nanoparticles with anti-cancer drugs for targeted cancer therapy using an external magnetic field.
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| 8. |
- Pamies, Ramon, et al.
(författare)
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Temperature-Induced Flocculation of Gold Particles with an Adsorbed Thermoresponsive Cationic Copolymer
- 2010
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:50, s. 21960-21968
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we report a study of the adsorption of a charged thermoresponsive poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammon ium chloride) [abbreviated as PNIPAAM(24)-b-PAMPTMA(+)(18)] block copolymer onto gold nanoparticles by means of dynamic light scattering (DLS), zeta-potential measurements, cryo-TEM, rheology small-angle light scattering (rheo-SALS), and UV-visible absorbance spectroscopy. At low surface coverage, the cationic copolymer was found to mediate flocculation of the particles at elevated temperatures, whereas at higher polymer concentration, the gold particles were stabilized by the adsorbed copolymer layer. The DLS results showed that the adsorbed polymer was compressed prior to flocculation at elevated temperatures and that the flocs coexisted with single particles. The latter finding was confirmed by cryo-TEM. Rheo-SALS measurements revealed that shear flow disrupted the large flocs formed at higher temperatures. UV-visible absorbance measurements demonstrated that the temperature-induced flocculation process gives rise to a red shift of the localized surface plasmon resonance (LSPR) peak, together with the appearance of a second peak at higher wavelengths.
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| 9. |
- Singh, Gurvinder, et al.
(författare)
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Synthesis of gadolinium oxide nanodisks and gadolinium doped iron oxide nanoparticles for MR contrast agents
- 2017
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Ingår i: Journal of materials chemistry. B. - : Royal Society of Chemistry (RSC). - 2050-750X .- 2050-7518. ; 5:3, s. 418-422
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we report the synthesis of differently sized gadolinium oxide nanodisks and gadolinium doped iron oxide spherical and cubic nanoparticles through the thermal decomposition of an oleate precursor. We also demonstrate that these nanoparticles are promising candidates for MR contrast agents.
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| 10. |
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