| 1. |
- Ahrén, Maria, et al.
(författare)
-
A simple polyol-free synthesis route to Gd 2O 3 nanoparticles for MRI applications : An experimental and theoretical study
- 2012
-
Ingår i: Journal of nanoparticle research. - : Springer. - 1388-0764 .- 1572-896X. ; 14:8
-
Tidskriftsartikel (refereegranskat)abstract
- Chelated gadolinium ions, e.g., Gd-DTPA, are today used clinically as contrast agents for magnetic resonance imaging (MRI). An attractive alternative contrast agent is composed of gadolinium oxide nanoparticles as they have shown to provide enhanced contrast and, in principle, more straightforward molecular capping possibilities. In this study, we report a new, simple, and polyol-free way of synthesizing 4-5-nm-sized Gd 2O 3 nanoparticles at room temperature, with high stability and water solubility. The nanoparticles induce high-proton relaxivity compared to Gd-DTPA showing r 1 and r 2 values almost as high as those for free Gd 3+ ions in water. The Gd 2O 3 nanoparticles are capped with acetate and carbonate groups, as shown with infrared spectroscopy, near-edge X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and combined thermogravimetric and mass spectroscopy analysis. Interpretation of infrared spectroscopy data is corroborated by extensive quantum chemical calculations. This nanomaterial is easily prepared and has promising properties to function as a core in a future contrast agent for MRI.
|
|
| 2. |
- Ausanio, G., et al.
(författare)
-
Influence of film thickness on topology and related magnetic interactions in Fe nanoparticle films
- 2013
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 15:8
-
Tidskriftsartikel (refereegranskat)abstract
- Fe nanoparticle (NP)-assembled thin films with different thickness were prepared by femtosecond-pulsed laser deposition using different deposition times. The proper selection of the deposition time allows to control, to a certain degree, the morphology and topology of the deposited Fe nanoparticles (NPs) assembly, fostering non-uniform dense assemblies of NPs, with the consequent reduction of the influence of the exchange interactions on the macroscopic magnetic properties with decreasing thickness. The magnetic behavior of the Fe NP-assembled films with decreasing thickness is characterized by higher coercive field (H-c) values (a factor approximate to 4.5) and a good compromise between the hysteresis loops squareness and moderate exchange interactions, strongly correlated with the NPs topology.
|
|
| 3. |
- Ballem, Mohamed A., et al.
(författare)
-
Mesoporous silica templated zirconia nanoparticles
- 2011
-
Ingår i: Journal of nanoparticle research. - : SpringerLink. - 1388-0764 .- 1572-896X. ; 13:7, s. 2743-2748
-
Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles of zirconium oxide (ZrO2)were synthesized by infiltration of a zirconia precursor(ZrOCl28H2O) into a SBA-15 mesoporous silicamold using a wet-impregnation technique. X-raydiffractometry and high-resolution transmission electronmicroscopy show formation of stable ZrO2nanoparticles inside the silica pores after a thermaltreatment at 550 C. Subsequent leaching out of thesilica template by NaOH resulted in well-dispersedZrO2 nanoparticles with an average diameter of*4 nm. The formed single crystal nanoparticles arefaceted with 110 surfaces termination suggesting it tobe the preferred growth orientation. A growth modelof these nanoparticles is also suggested.
|
|
| 4. |
- Boholm, Max, 1982, et al.
(författare)
-
The many faces of nano in newspaper reporting
- 2012
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 14:2, s. 722-740
-
Tidskriftsartikel (refereegranskat)abstract
- The morpheme nano in languages such as Swedish and English is a constituent of many words. This article linguistically analyses the meaning potential of nano by focusing on word use in a Swedish newspaper corpus comprising 2,564 articles (1.6 million words) covering a 22-year period (1988–2010). Close to 400 word forms having nano as a constituent have been identified and analyzed. The results suggest that nano covers a broad and heterogeneous conceptual field: (i) as a prefix of the SI system; (ii) in relation to the scientific activities of nanoscience and nanotechnology, including their sub-processes and actors; and (iii) in relation to objects. The identified meanings of nano, besides the standard definition (i.e. ‘billionth part’ in relation to SI units), are ‘operating at the nanometre level’ in relation to activities and their actors and ‘nanometre sized’ and ‘nanotechnological’ in relation to objects; in addition, the less precise and non-technical meaning ‘very small’ is identified. We discuss the implications of the findings for a hypothesis about media influence on public understanding of technology, suggesting that repeated findings in Europe and the USA of little self-reported understanding and knowledge of nanotechnology or nanoscience among the public make sense in light of the polysemy of nano reflected in its broad variety of verbal forms and usages.
|
|
| 5. |
- Bose, Partha Pratim, et al.
(författare)
-
Template-directed nucleation and growth of CdS nanocrystal : the role of helical and nonhelical nanofibers on their shape and size
- 2010
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 12:3, s. 713-718
-
Tidskriftsartikel (refereegranskat)abstract
- This study describes the use of chiral nature of synthetic self-assembled nanofibers for nucleation and growth of Cadmium sulfide (CdS) nanocrystals with different sizes and shapes in room temperature. The templates are built by immobilizing a peptide capping agent on the surface of synthetic self-assembled helical or nonhelical nanofibers and CdS nanocrystals were allowed to grow on them. It is observed that there are differences in shapes and sizes of the nanocrystals depending on the chiral nature of the nanofibers on which they were growing. Even the CdS nanocrystals grown on different chiral and achiral nanofibers differ markedly in their photoluminescence properties. Thus, here we introduce a new way of using chirality of nanofibers to nucleate and grow CdS nanocrystals of different shape, size, and optical property.
|
|
| 6. |
|
|
| 7. |
- Chinga-Carrasco, Gary, et al.
(författare)
-
Bleached and unbleached MFC nanobarriers: : Properties and hydrophobisation with hexamethyldisilazane
- 2012
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 14:12
-
Tidskriftsartikel (refereegranskat)abstract
- This study explores the production and surface modification of microfibrillated cellulose (MFC), based on unbleached and bleached Pinus radiata pulp fibres. Unbleached Pinus radiata pulp fibres tend to fibrillate easier by homogenisation without pre-treatment, compared to the corresponding bleached MFC. The resulting unbleached MFC films have higher barrier against oxygen, lower water wettability and higher tensile strength than the corresponding bleached MFC qualities. In addition, it is demonstrated that carboxymethylation can also be applied for production of highly fibrillated unbleached MFC. The nanofibril size distribution of the carboxymethylated MFC is narrow with diameters less than 20 nm, as quantified on high-resolution field-emission scanning electron microscopy images. The carboxymetylation had a larger fibrillation effect on the bleached pulp fibres than on the unbleached one. Importantly, the suitability of hexamethyldisilazane (HMDS) as a new alternative for rendering MFC films hydrophobic was demonstrated. TheHMDS-modifiedfilmsmade of carboxymethylated MFC had oxygen permeability levels better than 0.06 mL mm m-2 day-1 atm-1,which is a good property for some packaging applications.
|
|
| 8. |
- Chinga-Carrasco, Gary, et al.
(författare)
-
Inkjet-printed silver nanoparticles on nano-engineered cellulose films for electrically conducting structures and organic transistors: : concept and challenges
- 2012
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 14:11
-
Tidskriftsartikel (refereegranskat)abstract
- This study explores the suitability of microfibrillated cellulose (MFC) films as a substrate for printing electrically conductive structures and multilayer electronic structures such as organic field effect transistors. Various MFC qualities were tested, including mechanically produced MFC, 2,2,6,6-tetramethylpiperidinyl- 1-oxyl pre-treated MFC and carboxymethylated- MFC. The films differed significantly with respect to the surface structure. In addition, the carboxymethylated-MFC films were surface modified with hexamethyldisilazane (HMDS) to reduce the water-wettability of the films, and thus, improve the print resolution of the inkjet-printed silver (Ag) nanoparticles. The Ag-particles (diameter>50 nm) were printed on the HMDS-modified films, which were mainly composed of nanofibrils with diameters >20 nm. The effect of surface roughness and surface chemical characteristics on the ink spreading and print resolution of the Ag-structures was explored. It was demonstrated that organic transistors operating at low voltages can be fabricated on nano-engineered MFC films.
|
|
| 9. |
- Coelho, S. C., et al.
(författare)
-
Encapsulation of a proteasome inhibitor with gold-polysaccharide nanocarriers
- 2014
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16:4
-
Tidskriftsartikel (refereegranskat)abstract
- Organic-inorganic hybrid nanoparticles are potential effective systems for drug delivery in cancer therapy and diagnosis. Chitosan-gum arabic with entrapped gold nanoparticles were developed as a carrier for an anticancer drug bortezomib. The nanosystem was designed to enhance the proteasome inhibitor activity in pancreatic cell lines, S2-013 and hTERT-HPNE. The hydrodynamic diameter of chitosan-gum arabic-gold nanoparticles loaded with bortezomib is around 330 nm. Laser scanning confocal microscopy images show the uptake of the gold nanoparticle/bortezomib encapsulated in chitosan-gum arabic matrix and the fast internalization of these nano combinations into pancreatic cells. Cytotoxic assays assessed that positively charged nanosystems reduce the cell growth and cell proliferation of S2-013s, but the same effect was not observed in cytotoxic response in hTERT-HPNE cells. The outcomes of this study demonstrate the capacity of chitosan-gum arabic nanocarriers to deliver gold nanoparticles/anticancer drug and to increase the permeation and retention effect in S2-013 cells and minimize drug side effects in HPNE cells. © 2014 Springer Science+Business Media.
|
|
| 10. |
- Concina, Isabella, et al.
(författare)
-
Stabilisation of monometallic nanoparticles by polyamide 6
- 2011
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 13:3, s. 1289-1300
-
Tidskriftsartikel (refereegranskat)abstract
- Monometallic metal nanoparticles (Pd, Pt, Ag and Ru) stabilised by polyamide 6 (PA6) have been prepared via a polyol process sustained by microwave irradiation. PA6 proved to be a good stabiliser, being spherical particles with little dimensional dispersion identified by transmission electron microscopy. Due to the inclusion of the metals in small amount (up to 3% w/w) into the macromolecular lattice, the polymer underwent changes in thermal behaviour, which, however, do not impair the possibility to process the material. The observed changes in differential scanning calorimetry curves indicated that metal containing PA6 materials are less crystalline and ordered than pure PA6. This was confirmed by diffuse reflectance infrared Fourier transform analysis, which indicated that the introduction of the metal nanoparticles lowered the conformational order of the polymer matrix and partly disrupted the hydrogen bond network of the polyamide.
|
|
| 11. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
-
Multimethod 3D characterization of natural plate-like nanoparticles: shape effects on equivalent size measurements
- 2014
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16:5
-
Tidskriftsartikel (refereegranskat)abstract
- The fundamental properties and processes that govern nanoparticle behavior in colloidal dispersions are critical to predict their performance in applications and also their environmental and health implications. Illite is a platy clay mineral that is present in large amounts in aquatic environments and can be used as a model natural particle for environmental risk assessment. However, the high-aspect ratio of illite makes conventional analysis, usually assuming a spherical size, insufficient for the assessment of shape-dependent properties. In the current paper, a multimethod characterization of a suspension of illite particles was done using atomic force microscopy, scanning electron microscopy, dynamic light scattering (DLS), nanoparticle tracking analysis, differential centrifugal sedimentation, and centrifugal- field flow fractionation coupled to multiangle light scattering and DLS. The relation between the different measurands was investigated, and the effect of the shape on the equivalent particle size was reported. While some of the used techniques are capable of assessing the aspect ratio of illite, the results confirm the need for multiple techniques and analysis of different types of measurands especially for high-aspect-ratio particles.
|
|
| 12. |
- Jafri, Syed Hassan Mujtaba, et al.
(författare)
-
Stability optimisation of molecular electronic devices based on nanoelectrode-nanoparticle bridge platform in air and different storage liquids
- 2014
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16:12, s. 2811-
-
Tidskriftsartikel (refereegranskat)abstract
- The long-term stability of metal nanoparticle-molecule junctions in molecular electronic devices based on nanoelectrodes (NEL) is a major challenge in the effort to bring related molecular electronic devices to application. To optimize the reproducibility of molecular electronic nanodevices, the time-dependent modification of such junctions as exposed to different media needs to be known. Here, we have studied (1) the stability of Au-NEL and (2) the electrical stability of molecule-Au nanoparticle (AuNP) junctions themselves with the molecule being 1,8-octanedithiol (ODT). Both the NELs only and the junctions were exposed to air and liquids such as deionized water, tetrahydrofuran, toluene and tetramethylethylenediamine (TMEDA) over a period of 1 month. The nanogaps remained stable in width when stored in either deionized water or toluene, whereas the current through 1,8-octanedithiol-NP junctions remained most stable when stored in TMEDA as compared to other solvents. Although it is difficult to follow the chemical processes in such devices in the 10-nm range with analytical methods, the behavior can be interpreted from known interactions of solvent molecules with electrodes and ODT.
|
|
| 13. |
- Kreyling, Wolfgang G., et al.
(författare)
-
Generation and characterization of stable, highly concentrated titanium dioxide nanoparticle aerosols for rodent inhalation studies
- 2011
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1572-896X .- 1388-0764. ; 13:2, s. 511-524
-
Tidskriftsartikel (refereegranskat)abstract
- The intensive use of nano-sized titanium dioxide (TiO2) particles in many different applications necessitates studies on their risk assessment as there are still open questions on their safe handling and utilization. For reliable risk assessment, the interaction of TiO2 nanoparticles (NP) with biological systems ideally needs to be investigated using physico-chemically uniform and well-characterized NP. In this article, we describe the reproducible production of TiO2 NP aerosols using spark ignition technology. Because currently no data are available on inhaled NP in the 10-50 nm diameter range, the emphasis was to generate NP as small as 20 nm for inhalation studies in rodents. For anticipated in vivo dosimetry analyses, TiO2 NP were radiolabeled with V-48 by proton irradiation of the titanium electrodes of the spark generator. The dissolution rate of the V-48 label was about 1% within the first day. The highly concentrated, polydisperse TiO2 NP aerosol (3-6 x 10(6) cm(-3)) proved to be constant over several hours in terms of its count median mobility diameter, its geometric standard deviation, and number concentration. Extensive characterization of NP chemical composition, physical structure, morphology, and specific surface area was performed. The originally generated amorphous TiO2 NP were converted into crystalline anatase TiO2 NP by thermal annealing at 950 A degrees C. Both crystalline and amorphous 20-nm TiO2 NP were chain agglomerated/aggregated, consisting of primary particles in the range of 5 nm. Disintegration of the deposited TiO2 NP in lung tissue was not detectable within 24 h.
|
|
| 14. |
- Li, Cuiyan, et al.
(författare)
-
Polyacrylamide-metal nanocomposites : one-pot synthesis, antibacterial properties, and thermal stability
- 2013
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 15:9, s. UNSP 1922-
-
Tidskriftsartikel (refereegranskat)abstract
- The incorporation of inorganic nanoparticles into polymers is a hot research spot, since it endows the nanocomposites with new or improved properties by exploiting synergistic effects. Here we report a facile one-pot synthesis of polyacrylamide (PAM)-metal (M = Au, Ag, or Pd) nanocomposites in ethylene glycol (EG). The simultaneous polymerization of the acylamide (AM) monomer and formation of metal nanoparticles lead to a homogeneous distribution of metal nanoparticles in the PAM matrix. The sizes of Au, Ag, and Pd nanoparticles are 55.50 +/- 10.6, 14.15 +/- 2.57, and 7.74 +/- 1.82 nm, respectively. The reaction system only includes EG, AM monomer, and corresponding metal salt. EG acts as both the solvent and the reducing reagent. Also, no initiator for AM polymerization and no surfactant for stabilization of metal nanoparticles are used. Furthermore, this simple synthetic route does not rely on any special or expensive equipment, thus can be exploited to the synthesis of similar polymer-inorganic nanocomposites. Compared to PAM, the PAM-metal nanocomposites showed enhanced thermal stability and antibacterial properties.
|
|
| 15. |
- Nikkam, Nader, 1978-, et al.
(författare)
-
Novel Nanofluids Based on Mesoporous Silica for Enhanced Heat Transfer
- 2011
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 13:11, s. 6201-6206
-
Tidskriftsartikel (refereegranskat)abstract
- Nanofluids, which are liquids with engineered nanometer-sized particles suspensions, have drawn remarkable attraction from the researchers because of their enormous potential to enhance the efficiency in heat-transfer fluids. In the present study, water-based calcined mesoporous silica nanofluids were prepared and characterized. The commercial mesoporous silica (MPSiO2) nanoparticles were dispersed in deionized water by means of pH adjustment and ultrasonic agitation. MPSiO2 nanoparticles were observed to have an average particle size of 350 ± 100 nm by SEM analysis. The concentration of MPSiO2 was varied between 1 and 6 wt%. The physicochemical properties of nanofluids were characterized using various techniques, such as particle size analyzer, zeta-potential meter, TEM, and FT-IR. The thermal conductivity was measured by Transient Plane Source (TPS) method, and nanofluids showed a higher thermal conductivity than the base liquid for all the tested concentrations.
|
|
| 16. |
- Nilsson, Patrik, et al.
(författare)
-
Nano-objects emitted during maintenance of common particle generators: direct chemical characterization with aerosol mass spectrometry and implications for risk assessments
- 2013
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1572-896X .- 1388-0764. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- Nanotechnology gives us materials with enhanced or completely new properties. At the same time, inhalation of manufactured nano-objects has been related to an array of adverse biological effects. We characterized particle emissions, which occurred during maintenance of common metal nanoparticle generators and contrasted the properties of the emitted particles with those originally produced by the generators. A new approach using online aerosol mass spectrometry (AMS), for time-and size-resolved measurements of the particle chemical composition, was applied in combination with more conventional techniques for particle sampling and analysis, including electron microscopy. Emissions during maintenance work, in terms of mass and surface area concentration in the size range of 0.02-10 mu m, were dominated by large agglomerates (1-5 mu m). With AMS, we show that the particle composition depends on both generator type and maintenance task being performed and that the instrument can be used for highly time-resolved selective studies of metal nanoparticle emissions. The emitted agglomerates have a relatively high probability to be deposited in the lower respiratory tract, since the mean particle diameter coincided with a peak in the lung deposition curve. Each of these agglomerates consisted of a very high number (10(3)-10(5)/agglomerate) of nanometer-sized primary particles originating from the particle synthesis process. This made them possess large surface areas, one of the key properties in nanotoxicology. Similar agglomerates may be emitted in a wide range of processes when nanoparticles are manufactured or handled. The fate of such agglomerates, once deposited in the respiratory tract, is unknown and should therefore be considered in future particle toxicological studies. Our results highlight the importance of including micrometer-sized particles in exposure and emission assessments.
|
|
| 17. |
- Okoli, Chuka, et al.
(författare)
-
Protein-functionalized magnetic iron oxide nanoparticles : time efficient potential-water treatment
- 2012
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 14:10, s. 1194-
-
Tidskriftsartikel (refereegranskat)abstract
- Recent advances in nanoscience suggest that the existing issues involving water quality could be resolved or greatly improved using nanomaterials, especially magnetic iron oxide nanoparticles. Magnetic nanoparticles have been synthesized for the development and use, in association with natural coagulant protein for water treatment. The nanoparticles size, morphology, structure, and magnetic properties were characterized by transmission electron microscope, X-ray diffraction, and superconducting quantum interference device magnetometry. Purified Moringa oleifera protein was attached onto microemulsions-prepared magnetic iron oxide nanoparticles (ME-MION) to form stable protein-functionalized magnetic nanoparticles (PMO+ME-MION). The turbidity removal efficiency in both synthetic and surface water samples were investigated and compared with the commonly used synthetic coagulant (alum) as well as PMO. More than 90 % turbidity could be removed from the surface waters within 12 min by magnetic separation of PMO? ME-MION; whereas gravimetrically, 70 % removal in high and low turbid waters can be achieved within 60 min. In contrast, alum requires 180 min to reduce the turbidity of low turbid water sample. These data support the advantage of separation with external magnetic field (magnetophoresis) over gravitational force. Time kinetics studies show a significant enhancement in ME-MION efficiency after binding with PMO implying the availability of large surface of the ME-MION. The coagulated particles (impurities) can be removed from PMO+ME-MIONby washing with mild detergent or cleaning solution. To our knowledge, this is the first report on surface water turbidity removal using protein-functionalized magnetic nanoparticle.
|
|
| 18. |
- Promnimit, S., et al.
(författare)
-
Hydrothermal growth of ZnO hexagonal nanocrystals : Effect of growth conditions
- 2013
-
Ingår i: Journal of Nano Research. - : Trans Tech Publications Inc.. - 1662-5250 .- 1388-0764 .- 1572-896X. ; 21, s. 57-63
-
Tidskriftsartikel (refereegranskat)abstract
- Hexagonal ZnO nanocrystals were synthesized through a hydrothermal route under mild conditions (growth temperature of 90°C at atmospheric pressure). Pre-synthesized ZnO nanoparticles were used to serve as nucleation sites for the growth of the nanocrystals. The growth of ZnO nanorods was found to be surface independent. The dimensions of the hexagonal ZnO nanocrystals were observed to be dependent on the concentration of the reactants used (sources of Zn2+ and OH- ions), pH of the growth bath and also on the duration of crystal growth. The average diameter and height of the ZnO nanocrystals was found to be directly proportional to the concentration of the reactants as well as hydrolysis time. The orientation of the nanocrystals was found to be dependent upon the seeding method employed. Hexagonal single crystals of a wide range of dimensions and aspect ratios could be successfully synthesized through a control of growth parameters.
|
|
| 19. |
- Qian, Zhao, et al.
(författare)
-
Oxygen- and nitrogen-chemisorbed carbon nanostructures for Z-scheme photocatalysis applications
- 2012
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 14:8, s. 895-
-
Tidskriftsartikel (refereegranskat)abstract
- Here focusing on the very new experimental finding on carbon nanomaterials for solid-state electron mediator applications in Z-scheme photocatalysis, we have investigated different graphene-based nanostructures chemisorbed by various types and amounts of species such as oxygen (O), nitrogen (N) and hydroxyl (OH) and their electronic structures using density functional theory. The work functions of different nanostructures have also been investigated by us to evaluate their potential applications in Z-scheme photocatalysis for water splitting. The N-, O-N-, and N-N-chemisorbed graphene-based nanostructures (32 carbon atoms supercell, corresponding to lattice parameter of about 1 nm) are found promising to be utilized as electron mediators between reduction level and oxidation level of water splitting. The O- or OH-chemisorbed nanostructures have potential to be used as electron conductors between H-2-evolving photocatalysts and the reduction level (H+/H-2). This systematic study is proposed to understand the properties of graphene-based carbon nanostructures in Z-scheme photocatalysis and guide experimentalists to develop better carbon-based nanomaterials for more efficient Z-scheme photocatalysis applications in the future.
|
|
| 20. |
- Sahoo, Dibakar, et al.
(författare)
-
Gold nanoparticle induced conformational changes in heme protein
- 2011
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 13:12, s. 6755-6760
-
Tidskriftsartikel (refereegranskat)abstract
- Change of alpha-helical structure of heme protein (Hb) to a beta-sheet and random coil conformation because of the interaction of glycine capped gold nanoparticles (20-60 nm) as observed from attenuation total reflectance, absorption, Fourier transform infra red, and Circular Dichroism spectroscopy has been reported in this article. Upon interaction, protein takes a cylindrical shape of length 12 mu m and diameter 0.35 mu m as revealed from scanning electron microscopy and transmission electron microscopy. The Selected-Area Electron beam Diffraction pattern shows change of crystalline structure in GNP to amorphous nature with the interaction of Hb.
|
|
| 21. |
- Singh, Vidyadhar, et al.
(författare)
-
Assembly of tantalum porous films with graded oxidation profile from size-selected nanoparticles
- 2014
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16:5
-
Tidskriftsartikel (refereegranskat)abstract
- Functionally graded materials offer a way to improve the physical and chemical properties of thin films and coatings for different applications in the nanotechnology and biomedical fields. In this work, design and assembly of nanoporous tantalum films with a graded oxidation profile perpendicular to the substrate surface are reported. These nanoporous films are composed of size-selected, amorphous tantalum nanoparticles, deposited using a gas-aggregated magnetron sputtering system, and oxidized after coalescence, as samples evolve from mono- to multi-layered structures. Molecular dynamics computer simulations shed light on atomistic mechanisms of nanoparticle coalescence, which govern the films porosity. Aberration-corrected (S) TEM, GIXRD, AFM, SEM, and XPS were employed to study the morphology, phase and oxidation profiles of the tantalum nanoparticles, and the resultant films. Design and assembly of tantalum nanoparticle porous films with a graded oxidation profile perpendicular to the substrate surface were fabricated by magnetron-sputter inert-gas aggregation system. At the top-most layers of the film, the larger free-surface areas of nanoparticles enable the formation of thermodynamically stable Ta2O5.
|
|
| 22. |
- Singhal, Sonal, et al.
(författare)
-
Photoluminescence measurements in the phase transition region of Zn1-x Cd (x) S films
- 2010
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 12:4, s. 1415-1421
-
Tidskriftsartikel (refereegranskat)abstract
- Thin films of Zn1-x Cd (x) S (0.1 a parts per thousand currency sign x a parts per thousand currency sign 0.5) were prepared by using pulsed laser ablation technique on corning glass substrates. Phase transition from cubic to hexagonal in Zn1-x Cd (x) S films is determined by X-ray diffraction analysis. We observed a lowering in the phase transition temperature with increase in the cadmium concentration. Transmission electron microscopy suggests the crystalline nature of thin films with average particle size of 15 nm. The grown Zn1-x Cd (x) S samples show the high peak intensity ratio of the near band edge emission to the defect center luminescence even at room temperature, which indicates the small concentration of complex defects in the samples. Photoluminescence measurement show stoichiometric dependence of the energy band gap and is found to have quadratic dependence on x.
|
|
| 23. |
|
|
| 24. |
- Taglietti, A., et al.
(författare)
-
Mixing thiols on the surface of silver nanoparticles: Preserving antibacterial properties while introducing SERS activity
- 2013
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 15:11
-
Tidskriftsartikel (refereegranskat)abstract
- Controlling the surface composition of self-assembled monolayers is one of the major experimental challenges in nanotechnology. Despite the significant interest of the scientific community and the considerable number of publications related to this topic, the potential in this field is still far from being fully exploited. We present in this study a versatile method to coat silver nanoparticles (AgNPs) having average diameter of 7 nm with mixed monolayers of two thiols, achieving a precise control of surface composition. Different combinations of thiols have been investigated, and the nanomaterials obtained have been characterized by complementary experimental techniques, addressing the composition of the mixed monolayer. The surface-enhanced Raman spectroscopy (SERS) effect on a Raman reporter (7-mercapto-4-methylcoumarine) introduced into the mixed monolayers has also been investigated. The antibacterial activity of the coated AgNPs was investigated, showing that the colloids were active against Escherichia coli and Staphilococcus aureus irrespective of the nature of the mixed monolayer. These materials are good candidates as SERS-tags for biological applications. © Springer Science+Business Media 2013.
|
|
| 25. |
- Topel, Seda Demirel, et al.
(författare)
-
Hybrid silica nanoparticles for sequestration and luminescence detection of trivalent rare-earth ions (Dy3+ and Nd3+) in solution
- 2014
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16
-
Tidskriftsartikel (refereegranskat)abstract
- New hybrid material-based adsorbents acting also as luminescent probes upon uptake of trivalent rare-earth (RE) ions Nd3+ and Dy3+ have been developed. SiO2 NPs functionalized by three different organic ligands, N-aminopropylen-amidoiminodiacetic acid (L1), pyridine-alpha,beta-dicarboxylic acid bis(propylenamide) (L2), and N-propylen-iminodiacetic acid (L3), have been produced and fully characterized by C-13, H-1, and Si-29 solid-state NMR, FTIR, TGA, XRD, TEM, nitrogen gas adsorption, and also by NTA and DLS in solution. The synthesized hybrid materials are well dispersible and stable in aqueous solutions according to NTA and consist of spheres with diameters less than 100 nm. Their affinities to the lanthanide ions Dy3+ and Nd3+ have been investigated in aqueous solution and characterized by SEM-EDS and complexometric titration, demonstrating that they can be successfully used as adsorbents for sequestration of trivalent RE ions. The adsorbed RE ions can efficiently be desorbed from saturated nanoadsorbents by addition of hydrochloric acid. The produced nanomaterials may also be used as luminescent probes for Dy3+ and Nd3+ ions in solution.
|
|
| 26. |
- Unal, B., et al.
(författare)
-
Synthesis, structural and conductivity characterization of alginic acid-Fe3O4 nanocomposite
- 2010
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 12:8, s. 3039-3048
-
Tidskriftsartikel (refereegranskat)abstract
- Alginic acid-Fe3O4 nanocomposite is synthesized by the precipitation of Fe3O4 in the presence of alginic acid (AA). Structural, surface, morphological, thermal and electrical transport properties of the nanocomposite were performed by XRD, FT-IR, TEM-SEM, TGA and conductivity measurements respectively. FT-IR analysis revealed that Fe3O4 NPs are strongly capped with AA and TGA analysis showed that nanocomposite have 80% of Fe3O4 content. TEM analysis of Fe3O4 NPs show an average particle size of 9.5 nm, and upon nanocomposite formation with AA these particles are observed to form aggregates of similar to 150 nm. The frequency-dependency of the AC conductivity show electrode polarization effect. Analysis of electrical modulus and dielectric permittivity functions suggest that ionic and polymer segmental motions are strongly coupled. DC electrical conductivity is strongly temperature dependent, and is classified into three regions over a limited temperature range of up to 100 A degrees C.
|
|
| 27. |
- Uzun, K., et al.
(författare)
-
Covalent immobilization of invertase on PAMAM-dendrimer modified superparamagnetic iron oxide nanoparticles
- 2010
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 12:8, s. 3057-3067
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, polyamidoamine (PAMAM) dendrimer was synthesized on the surface of superparamagnetite nanoparticles to enhance invertase immobilization. The amount of immobilized enzyme on the surface-hyperbranched magnetite nanoparticle was up to 2.5 times (i.e., 250%) as much as that of magnetite nanoparticle modified with only amino silane. Maximum reaction rate (V (max)) and Michaelis-Menten constant (K (m)) were determined for the free and immobilized enzymes. Various characteristics of immobilized invertase such as; the temperature activity, thermal stability, operational stability, and storage stability were evaluated and results revealed that stability of the enzyme is improved upon immobilization.
|
|
| 28. |
- Vogt, Carmen M., et al.
(författare)
-
High quality and tuneable silica shell-magnetic core nanoparticles
- 2010
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 12:4, s. 1137-1147
-
Tidskriftsartikel (refereegranskat)abstract
- Obtaining small (<50 nm), monodispersed, well-separated, single iron oxide core-silica SiO2) shell nanoparticles for biomedical applications is still a challenge. Preferably, they are synthesized by inverse microemulsion method. However, substantial amount of aggregated and multicore core- shell nanoparticles is the undesired outcome of the method. In this study, we report on the production of less than 50 nm overall size, monodispersed, free of necking, single core iron oxide-SiO2 shell nanoparticles with tuneable shell thickness by a carefully optimized inverse microemulsion method. The high degree of control over the process is achieved by understanding the mechanism of core-shell nanoparticles formation. By varying the reaction time and recursor concentration, the thickness of silica layer an the core nanoparticles can be finely adjusted from to 13 nm. Residual reactions during the workup were inhibited by a combination of pH control with hock freezing and ultracentrifuging. These highquality tuneable core-shell nanocomposite particles exhibit superparamagnetic character and sufficiently high magnetization with great potential for biomedical applications (e.g. MRI, cell separation and magnetically driven drug delivery systems) either as-prepared or by additional surface modification for improved biocompatibility.
|
|
| 29. |
- Wang, Qi, et al.
(författare)
-
Synthesis of water-dispersible photoluminescent silicon nanoparticles and their use in biological fluorescent imaging
- 2011
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1572-896X .- 1388-0764. ; 13:1, s. 405-413
-
Tidskriftsartikel (refereegranskat)abstract
- Water-dispersible silicon nanoparticles (Si-NPs) are desirable for applications in biological techniques. A simplified method to synthesize such particles is reported here. The resulting Si-NPs are water-dispersible and luminescent. Under the excitation of UV light, the Si-NPs emit strong red light with a peak maximum at 606 nm and a quantum yield of 6%. They are highly stable, and remain so over several weeks. Fourier Transform Infrared (FTIR) spectroscopy shows a visible Si-CH2 scissoring vibration mode. Furthermore, the surface chemical bondings were confirmed by X-ray photoelectron spectroscopy (XPS). In the Si2p and C1s core levels, Si-C components are observed. The diameters of the synthesized Si-NPS as measured by atomic force microscope (AFM) are approximately 5 nm. Furthermore, the nanoparticles can be taken up by cultured cells. Fluorescence images of Si-NPs within MCF-7 human breast cancer cells show they are distributed throughout the cell tissue.
|
|
| 30. |
- Wang, Xiaodi, 1981-, et al.
(författare)
-
Synthesis of uniform quasi-octahedral CeO2 mesocrystals via a surfactant-free route
- 2011
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 13:11, s. 5879-5885
-
Tidskriftsartikel (refereegranskat)abstract
- A facile surfactant-free nonaqueous method is presented to prepare uniform quasi-octahedral ceria, CeO 2 , mesocrystals, in which only Ce(NO 3 ) 3 and octanol were used as the reactants at a reaction temperature of 150 °C. CeO 2 sample synthesized using this technique consists of well-dispersed quasi-octahedrons and exhibits an uniform size and morphology. Based on structural characterization, it is proposed that the CeO 2 mesostructure was formed by self-assembly of primary nanocrystals based on unique 3D oriented-attachment mechanism. Optical characterization exhibited a strong quantum confinement, revealing small size of primary nanocrystals. The thermal stability and UV–Vis study reveal CeO 2 mesocrystal has various potential for high temperature applications and optical apparatus applications.
|
|
| 31. |
- Wu, Ming-Chung, et al.
(författare)
-
Photocatalytic activity of nitrogen-doped TiO2-based nanowires : a photo-assisted Kelvin probe force microscopy study
- 2013
-
Ingår i: Journal of nanoparticle research. - : Springer. - 1388-0764 .- 1572-896X. ; 16:1, s. Article Number: UNSP 2143-
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, a set of nitrogen-doped TiO2-based nanomaterials demonstrating photocatalytic activity was developed by combining the efforts of lattice doping and metal nanoparticle decoration and tested for photo-degradation of methylene blue dye by applying solar simulator irradiation. The surface potential shifts of these TiO2-based photocatalytic nanomaterials measured by Kelvin probe force microscope have been used to study the degree of electron generation of the photocatalysts after irradiation and were well correlated with the photocatalytic activity. The nitrogen-doped TiO2 nanowires decorated with Pt nanoparticles can induce obvious electron accumulation and result in a large shift of surface potential. The analysis shows a clear correlation between the surface potential shift and the photodegradation activity. Furthermore, a thorough comparative photocatalytic activity study combined with X-ray photoelectron spectroscopy analysis of the materials-doped with nitrogen under various conditions-reveals that the photocatalytic efficiency of the catalysts is maintained even if the lattice doping is leached e.g., by thermal treatments after doping. By monitoring the surface potential shifts of various TiO2-based photocatalysts by photo-assisted Kelvin probe force microscopy, we obtain a useful tool for developing novel materials with high photocatalytic activity.
|
|
| 32. |
- Ye, Fei, et al.
(författare)
-
Multifunctional core-shell nanoparticles : superparamagnetic, mesoporous, and thermosensitive
- 2011
-
Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 13:11, s. 6157-6167
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 33. |
- Holmlid, Leif, 1942
(författare)
-
Nanometer interatomic distances in Rydberg Matter clusters confirmed by phase-delay spectroscopy
- 2010
-
Ingår i: Journal of Nanoparticle Research. - 1388-0764. ; 12:1, s. 273-284
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, rotational spectroscopy in the radio frequency range was used to determine the bond lengths in several types of potassium Rydberg Matter (RM) clusters with high precision (Mol Phy 105: 933–939, 2007). Due to the large bond lengths of a few nm and well-ordered structure of such clusters, it is expected that light scattering can be used to determine their dimensions. A weak carbon dioxide laser beam is introduced collinearly into a tunable RM cavity. When RM is formed, a very pronounced fringe structure with several hundred fringes is observed at the detector as a function of the grating position. These fringes show a phase delay of the carbon dioxide laser light caused by reflections within the RM clusters. The delay lengths derived from the fringe structure give distances between the rows of atoms in the clusters. The excitation level of the most easily observed clusters is n = 5. Clusters with n = 6, 7, and 8 are also commonly detected. The bond distance for n = 5 is found to be 3.804 ± 0.015 nm, while that for n = 6 is 5.525 ± 0.014 nm, in accurate agreement with values from rotational spectroscopy.
|
|
