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Träfflista för sökning "WFRF:(Toprak Muhammet 1973 ) "

Sökning: WFRF:(Toprak Muhammet 1973 )

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1.
  • Abdollahi, Farnoosh, et al. (författare)
  • Angiogenesis in bone tissue engineering via ceramic scaffolds: A review of concepts and recent advancements
  • 2024
  • Ingår i: Biomaterials Advances. - : Elsevier BV. - 2772-9516 .- 2772-9508. ; 159
  • Forskningsöversikt (refereegranskat)abstract
    • Due to organ donor shortages, long transplant waitlists, and the complications/limitations associated with auto and allotransplantation, biomaterials and tissue-engineered models are gaining attention as feasible alternatives for replacing and reconstructing damaged organs and tissues. Among various tissue engineering applications, bone tissue engineering has become a promising strategy to replace or repair damaged bone. We aimed to provide an overview of bioactive ceramic scaffolds in bone tissue engineering, focusing on angiogenesis and the effect of different biofunctionalization strategies. Different routes to angiogenesis, including chemical induction through signaling molecules immobilized covalently or non-covalently, in situ secretion of angiogenic growth factors, and the degradation of inorganic scaffolds, are described. Physical induction mechanisms are also discussed, followed by a review of methods for fabricating bioactive ceramic scaffolds via microfabrication methods, such as photolithography and 3D printing. Finally, the strengths and weaknesses of the commonly used methodologies and future directions are discussed.
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3.
  • Akan, Rabia (författare)
  • Metal-assisted chemical etching for nanofabrication of hard X-ray zone plates
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Hard X-ray scanning microscopes, or nanoprobes, make it possible to image samples and probe their chemical, elemental and structural properties at nanoscale resolution. This is enabled by the use of nanofocusing optics. Commonly used optics in nanoprobes for high resolution X-ray experiments are zone plates. Zone plates are circular diffraction optics with radially decreasing grating periods. Their performance depends on their geometrical properties and material. The width of the outermost zone, which today is in the order of a few tens of nanometers, defines the zone plate resolution, while the zone thickness and the material define the X-ray focusing efficiency. For hard X-ray zone plates, the required zone thickness is several micrometers. Therefore, high-aspect ratio nanostructures are a prerequisite for high-resolution, high-efficiency zone plates. The very small structures together with the high-aspect ratios make zone plates one of the most challenging devices to fabricate. A wet-chemical nanofabrication process that has proved its capability of providing silicon nanostructures with ultra-high aspect ratios is metal-assisted chemical etching (MACE). MACE is an electroless, autocatalytic pattern transfer method that uses an etching solution to selectively etch a predefined noble metal pattern into silicon. In this thesis, MACE is optimized specifically for zone plate nanostructures and used in the development of a new zone plate device nanofabrication process. The MACE optimization for silicon zone plate nanostructures involved a systematic investigation of a wide parameter space. The preferable etching solution composition, process temperature, zone plate catalyst design and silicon type were identified. Parameter dependencies were characterized with respect to etching depth and verticality, mechanical stability of zones and silicon surface roughness. Zone plate molds with aspect ratios of 30:1 at 30 nm zone widths were nanofabricated using the optimized MACE process. For use with hard X-rays, the silicon molds were metallized with palladium using electroless deposition (ELD). The first order diffraction efficiency of such a palladium/silicon zone plate was characterized as 1.9 %. Both MACE for the zone plate pattern transfer and ELD for the silicon mold metalization are conceptually simple, relatively low-cost and accessible methods, which opens up for further developments of zone plate device nanofabrication processes.
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4.
  • Al-Farsi, Hissa M., et al. (författare)
  • Effects of the Antimicrobial Peptide LL-37 and Innate Effector Mechanisms in Colistin-Resistant Klebsiella pneumoniae With mgrB Insertions
  • 2019
  • Ingår i: Frontiers in Microbiology. - : FRONTIERS MEDIA SA. - 1664-302X. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Colistin is a polypeptide antibiotic drug that targets lipopolysaccharides in the outer membrane of Gram-negative bacteria. Inactivation of the mgrB-gene is a common mechanism behind colistin-resistance in Klebsiella pneumoniae (Kpn). Since colistin is a cyclic polypeptide, it may exhibit cross-resistance with the antimicrobial peptide LL-37, and with other innate effector mechanisms, but previous results are inconclusive. Objective To study potential cross-resistance between colistin and LL-37, as well as with other innate effector mechanisms, and to compare virulence of colistin-resistant and susceptible Kpn strains. Materials/Methods Carbapenemase-producing Kpn from Oman (n = 17) were subjected to antimicrobial susceptibility testing and whole genome sequencing. Susceptibility to colistin and LL-37 was studied. The surface charge was determined by zeta-potential measurements and the morphology of treated bacteria was analyzed with electron microscopy. Bacterial survival was assessed in human whole blood and serum, as well as in a zebrafish infection-model. Results Genome-analysis revealed insertion-sequences in the mgrB gene, as a cause of colistin resistance in 8/17 isolates. Colistin-resistant (Col-R) isolates were found to be more resistant to LL-37 compared to colistin-susceptible (Col-S) isolates, but only at concentrations >= 50 mu g/ml. There was no significant difference in surface charge between the isolates. The morphological changes were similar in both Col-R and Col-S isolates after exposure to LL-37. Finally, no survival difference between the Col-R and Col-S isolates was observed in whole blood or serum, or in zebrafish embryos. Conclusion Cross-resistance between colistin and LL-37 was observed at elevated concentrations of LL-37. However, Col-R and Col-S isolates exhibited similar survival in serum and whole blood, and in a zebrafish infection-model, suggesting that cross-resistance most likely play a limited role during physiological conditions. However, it cannot be ruled out that the observed cross-resistance could be relevant in conditions where LL-37 levels reach high concentrations, such as during infection or inflammation.
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5.
  • Alaghmandfard, A., et al. (författare)
  • Recent advances in the modification of carbon-based quantum dots for biomedical applications
  • 2021
  • Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 120
  • Forskningsöversikt (refereegranskat)abstract
    • Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface functionalization, polymer capping, nano-composite and core-shell structures, and the drawbacks and challenges in each of these methods are discussed.
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6.
  • Almessiere, M. A., et al. (författare)
  • Effects of Ce-Dy rare earths co-doping on various features of Ni-Co spinel ferrite microspheres prepared via hydrothermal approach
  • 2021
  • Ingår i: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 14, s. 2534-2553
  • Tidskriftsartikel (refereegranskat)abstract
    • The effects of Ce-Dy co-doping on the crystal structure, optical, dielectric, magnetic properties, and hyperfine interactions of Ni-Co spinel ferrite microspheres synthesized hydrothermally have been studied. A series of ferrites with the general formula Ni0.5-Co0.5CexDyxFe2-2xO4 were synthesized with x values ranging from 0.00 to 0.10. The phase, crystallinity, and morphology of ferrite microspheres were analyzed by X-ray powder diffractometry (XRD), scanning and transmission electron microscopes (SEM and TEM), respectively. The structural analyses of the synthesized ferrite microspheres confirmed their high purity and cubic crystalline phase. The Diffuse reflectance spectroscopic (DRS) measurements were presented to calculate direct optical energy band gaps (E-g) and is found in the range 1.63 eV - 1.84 eV. Fe-57 Mossbauer spectroscopy showed that the hyperfine magnetic field of tetrahedral (A) and octahedral (B) sites decreased with the substitution of Dy3+-Ce3+ ions that preferrentially occupy the B site. The impact of the rare-earth content (x) on the magnetic features of the prepared NiCo ferrite microspheres was investigated by analyzing M-H loops, which showed soft ferrimagnetism. The magnetic features illustrate a great impact of the incorporation of Ce3+-Dy3+ ions within the NiCo ferrite structure. The saturation magnetization (M-s), remanence (M-r), and coercivity (H-c) increased gradually with increasing Ce-Dy content. At x = 0.04, M-s, M-r, and H-c attain maximum values of about 31.2 emu/g, 11.5 emu/g, and 512.4 Oe, respectively. The Bohr magneton (n(B)) and magneto-crystalline anisotropy constant (K-eff) were also determined and evaluated with correlation to other magnetic parameters. Further increase in Ce3+-Dy3+ content (i.e., x >= 0.06) was found to decrease M-s, M-r, and H-c values. The variations in magnetic parameters (M-s, M-r, and H-c) were largely caused by the surface spins effect, the variations in crystallite/particle size, the distribution of magnetic ions into the different sublattices, the evolutions of magneto-crystalline anisotropy, and the variations in the magnetic moment (n(B)). The squareness ratios were found to be lower than the predicted theoretical value of 0.5 for various samples, indicating that the prepared Ce-Dy substituted NiCo ferrite microspheres are composed of NPs with single-magnetic domain (SMD). Temperature and frequency-dependent electrical and dielectric measurements have been done to estimate the ac/dc conductivity, dielectric constant, and tangent loss values for all the samples. The ac conductivity measurements confirmed the power-law rules, largely dependent on Ce-Dy content. Impedance analysis stated that the conduction mechanisms in all samples are mainly due to the grains-grain boundaries. The dielectric constant of NiCo ferrite microspheres give rise to normal dielectric distribution, with the frequency depending strongly on the Ce-Dy content. The observed variation in tangential loss with frequency can be attributed to the conduction mechanism in ferrites, like Koop's phenomenological model.
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7.
  • Almessiere, M. A., et al. (författare)
  • Review on functional bi-component nanocomposites based on hard/soft ferrites : Structural, magnetic, electrical and microwave absorption properties
  • 2021
  • Ingår i: Nano-Structures and Nano-Objects. - : Elsevier B.V.. - 2352-507X. ; 26
  • Tidskriftsartikel (refereegranskat)abstract
    • Bi-component hard (H) (hexaferrite) and soft (S) (spinel) ferrites nanocomposites are gaining interest scientifically and technically, not only for combining the high magnetization of spinel ferrite nanomaterials and the high coercivity of hexaferrite magnetic nanomaterials but also for the outstanding exchange-coupling behavior among hard and soft magnetic phase. The improved magnetic features lead to produce a new nanocomposite with higher microwave absorption capacity in comparison with ferrites with a single absorption mechanism. Exchange-coupled effect has a potential application based on microwave absorption, recording media, permanent magnets, biomedical and other applications. Intensive studies have been conducted on this topic to produce hard/soft (H/S) ferrite nanocomposites with establishment of exchange coupled effect between the two phases. Preparation methods, microstructure, magnetics features, microwave and dielectric properties, and applications are elaborated. Consequently, a comprehensive effort has been made to contain an original reference investigating in detail the precise outcomes of the published papers. 
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8.
  • Arsana, Komang G.Y., et al. (författare)
  • Laboratory Liquid-Jet X-ray Microscopy and X-ray Fluorescence Imaging for Biomedical Applications
  • 2024
  • Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 25:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Diffraction-limited resolution and low penetration depth are fundamental constraints in optical microscopy and in vivo imaging. Recently, liquid-jet X-ray technology has enabled the generation of X-rays with high-power intensities in laboratory settings. By allowing the observation of cellular processes in their natural state, liquid-jet soft X-ray microscopy (SXM) can provide morphological information on living cells without staining. Furthermore, X-ray fluorescence imaging (XFI) permits the tracking of contrast agents in vivo with high elemental specificity, going beyond attenuation contrast. In this study, we established a methodology to investigate nanoparticle (NP) interactions in vitro and in vivo, solely based on X-ray imaging. We employed soft (0.5 keV) and hard (24 keV) X-rays for cellular studies and preclinical evaluations, respectively. Our results demonstrated the possibility of localizing NPs in the intracellular environment via SXM and evaluating their biodistribution with in vivo multiplexed XFI. We envisage that laboratory liquid-jet X-ray technology will significantly contribute to advancing our understanding of biological systems in the field of nanomedical research.
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9.
  • Azadpour, Behnam, et al. (författare)
  • Magnetically-assisted viral transduction (magnetofection) medical applications : An update
  • 2023
  • Ingår i: Biomaterials Advances. - : Elsevier BV. - 2772-9516 .- 2772-9508. ; 154
  • Forskningsöversikt (refereegranskat)abstract
    • Gene therapy involves replacing a faulty gene or adding a new gene inside the body's cells to cure disease or improve the body's ability to fight disease. Its popularity is evident from emerging concepts such as CRISPR-based genome editing and epigenetic studies and has been moved to a clinical setting. The strategy for therapeutic gene design includes; suppressing the expression of pathogenic genes, enhancing necessary protein production, and stimulating the immune system, which can be incorporated into both viral and non-viral gene vectors. Although non-viral gene delivery provides a safer platform, it suffers from an inefficient rate of gene transfection, which means a few genes could be successfully transfected and expressed within the cells. Incorporating nucleic acids into the viruses and using these viral vectors to infect cells increases gene transfection efficiency. Consequently, more cells will respond, more genes will be expressed, and sustained and successful gene therapy can be achieved. Combining nanoparticles (NPs) and nucleic acids protects genetic materials from enzymatic degradation. Furthermore, the vectors can be transferred faster, facilitating cell attachment and cellular uptake. Magnetically assisted viral transduction (magnetofection) enhances gene therapy efficiency by mixing magnetic nanoparticles (MNPs) with gene vectors and exerting a magnetic field to guide a significant number of vectors directly onto the cells. This research critically reviews the MNPs and the physiochemical properties needed to assemble an appropriate magnetic viral vector, discussing cellular hurdles and attitudes toward overcoming these barriers to reach clinical gene therapy perspectives. We focus on the studies conducted on the various applications of magnetic viral vectors in cancer therapies, regenerative medicine, tissue engineering, cell sorting, and virus isolation.
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10.
  • Batili, Hazal, et al. (författare)
  • A comparative study on the surface chemistry and electronic transport properties of Bi2Te3 synthesized through hydrothermal and thermolysis routes
  • 2024
  • Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 682
  • Tidskriftsartikel (refereegranskat)abstract
    • Bismuth telluride-Bi2Te3 is the most promising material for harvesting thermal energy near room temperature. There are numerous works on Bi2Te3 reporting significantly different transport properties, with no clear connection to the synthetic routes used and the resultant surface chemistry of the synthesized materials. It is of utmost importance to characterize the constituent particles’ surface and interfaces to get a better understanding of their influence on the transport properties, that will significantly improve the material design starting from the synthesis step. Electrophoretic deposition (EPD) is a promising technique, enabling the formation of thick films using colloidally stabilized suspensions of pre-made nanoparticles, which can enable the study of the effect of surface chemistry, in connection to the synthetic route, on the material's transport properties. In order to explore the differences in surface chemistry and the resultant transport properties in relation to the synthetic scheme used, here we report on Bi2Te3 synthesised through two wet-chemical routes in water (Hydro-) and oil (Thermo-) as the solvents. XRD analysis showed a high phase purity of the synthesized materials. SEM analysis revealed hexagonal platelet morphology of the synthesized materials, which were then used to fabricate EPD films. Characterization of the EPD films reveal significant differences between the Hydro- and Thermo-Bi2Te3 samples, leading to about 8 times better electrical conductivity values in the Thermo-Bi2Te3. XPS analysis revealed a higher metal oxides content in the Hydro-Bi2Te3 sample, contributing to the formation of a resistive layer, thus lowering the electrical conductivity. Arrhenius plots of electrical conductivity vs inverse temperature was used for the estimation of the activation energy for conduction, revealing a higher activation energy need for the Hydro-Bi2Te3 film, in agreement with the resistive barrier oxide content. Both the samples exhibited negative Seebeck coefficient (S) in the order of 160–170 mV/K. The small difference in S of Hydro- and Themo-Bi2Te3 films was explained by the effective medium theory, revealing that the magnitude of S is linearly correlated with the surface oxide content. Based on the findings, TE materials synthesized through thermolysis route is recommended for further studies using soft treatment/processing of pre-made TE materials. EPD platform presented here is shown to clearly expose the differences in the electronic transport in connection to nanoparticle surface chemistry, proving a promising methodology for the evaluation of morphology, size and surface chemistry dependence of electronic transport for a wide range of materials.
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11.
  • Batili, Hazal, et al. (författare)
  • Electrophoretic assembly and electronic transport properties of rapidly synthesized Sb2Te3 nanoparticles
  • 2023
  • Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 637
  • Tidskriftsartikel (refereegranskat)abstract
    • With the recent advances in thermoelectric (TE) technology, there is an increasing demand to develop thick films that would enable large-scale TE devices. Assembly of TE-films from size and morphology-controlled nano particles has been a challenging issue that can be addressed by the use of electrophoretic deposition (EPD) technique. In this work, morphology-controlled Sb2Te3 nanoparticles were synthesized through microwave assisted thermolysis, which were subsequently used for EPD of TE films on specially developed glass substrates. The electronic transport properties were measured in the temp-range of 22-45 degrees C. The as-made EPD films showed a high initial resistance, ascribed to high porosity and the presence of surface oxide/passivating layers. The impact of two types of small organic molecules-as hexanedithiol and dodecanethiol, on the electronic transport was investigated, resulting in a significant improvement in the electrical conductivity of the films. The XPS analysis suggests that the thiols bind to the surface of nanoparticles through formation of sulfides. Seebeck coefficient in the range of + 160 to + 190 & mu;V/K was measured, revealing the p-type transport through the deposited films. Finally, a power factor of about 2.5 & mu;W/K2.m was estimated the first time for p-type EPD films, revealing the potential of the developed nanoparticles and substrate, the small molecule additives and the EPD process presented in this work.
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12.
  • Batili, Hazal, et al. (författare)
  • Electrophoretic Deposition and Characterization of Bi2Te3 Synthesized through Hydrothermal and Thermolysis Routes
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Bismuth telluride-Bi2Te3 is a promising material for harvesting thermal energyfor applications near room temperature, where large-area applications requirenew methods of depositing pre-made particulate materials. Electrophoretic deposition(EPD) technique has the promise of enabling the formation of thickfilms using colloidally stabilized suspensions of pre-made nanoparticles. It isvery important to understand the thermoelectric (TE) materials’ performancein relation to the synthetic process, to enable promising and scalable materialstechnologies. EPD films allow to study the effect of surface chemistry, stronglylinked to the synthetic route, on the material’s physico-chemical and transportproperties. Here we report on the synthesis of Bi2Te3 through wet-chemicalreactions performed in two different media as water (hydrothermal-Hydro) andoil (thermolysis-Thermo). Synthesized materials possess platelet morphology,which were then used to fabricated EPD films on specially developed glass substrates. Characterization of the materials and films reveal significant differencesbetween the surface chemistry of the EPD films of Hydro- and Thermo-Bi2Te3samples, where a higher content of metal oxide phases are observed in the Hydro-Bi2Te3 sample. This has a big impact the electronic transport properties, asrevealed by about nine times higher resistance, confirmed by significantly higheractivation energy, of the Hydro-Bi2Te3 film as compared to the Thermo-Bi2Te3film. Slight difference in the Seebeck coefficient (S) was explained by the effectivemedium theory, revealing that the magnitude of S is linearly correlatedwith the surface oxide content. Based on the findings, TE materials synthesizedthrough thermolysis route is recommended for future studies focusing on EPD of TE materials.
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13.
  • Batili, Hazal, et al. (författare)
  • On the electrophoretic deposition of Bi2Te3 nanoparticles through electrolyte optimization and substrate design
  • 2022
  • Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 649, s. 129537-
  • Tidskriftsartikel (refereegranskat)abstract
    • Assembly of thermoelectric nanostructures with pre-defined morphology and surface chemistry on solid sub-strates has been one of the challenges for in-plane TE devices. Electrophoretic deposition (EPD) has the potential to be used for this purpose, where the use of non-conductive substrates is required to enable a reliable evaluation of the transport property of electrically active films. Bi2Te3 nanoparticles, which were synthesized using microwave-assisted hydrothermal route, were used for the EPD of thermoelectric films on glass substrates. A special substrate was fabricated using maskless photolithography, to evaluate the electronic transport properties of the TE films without the interference of the substrate. Electrolyte composition was optimized for high mobility of the suspended nanoparticles, and Bi2Te3 EPD films were fabricated with a high deposition rate, reaching 10 mu m/min. Initial EPD films showed high resistivity, ascribed to the surface oxide layer and capping ligands. The resistance was significantly reduced by the addition of a dithiol molecular linker, capable of interconnecting the Bi2Te3 nanoparticles through ligand-exchange. Seebeck coefficient in the range-150 to-180 mu V/K was measured, revealing the transport through the deposited films. Finally, a power factor of 169 nW/K-2.m was estimated, revealing the potential for the application of this technology to large area TE films as active coatings using the developed EPD process.
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14.
  • Batili, Hazal (författare)
  • Synthesis, Electrophoretic Deposition, and Characterization of Nanostructured Thermoelectric Materials
  • 2023
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The world’s increasing demand for energy and supplying this energy dominantlyfrom fossil fuels has a major impact on global climate change. Theenergy crisis has gotten more alarming in the recent years which increasedthe motivation for replacing fossil fuels with greener routes for energy harvest.There are various technologies developed for harvesting energy, andthe ability to recover energy from waste heat at a wide range of temperatures (from room temperature to more than 1000 ∘C) distinguished thethermoelectric (TE) materials from the rest. The drawback about the thermoelectricdevices is that they are too inefficient to be cost-effective in manyapplications, and the developments in nanotechnology is providing somesolutions to increase the efficiency of these materials and devices.The field of thermoelectrics suffer from large discrepancy of theresults in the literature, which is generally attributed to the variations inthe materials qualities, urging a need for the development of synthetictechniques that can lead to large-scale TE materials in reasonable timeframe. In this thesis, three different routes for rapid, scalable, and energyefficient, wet-chemical synthetic techniques for bismuth chalcogenidecompounds are presented. Microwave assisted heating during reactionprovided better control over the particle properties while reducing thereaction time and carbon footprint of the synthetic method, leading tomaterials bismuth chalcogenides with promising TE transport propertiesin a scalable and reproducible manner.Hybrid TE materials, and recently emerging solid-liquid TE materialsconcept, requires fabrication of porous TE films, to study the effect of variousinterfaces, including solid and liquid electrolytes. For this purpose, wedeveloped and optimized the electrophoretic deposition (EPD) process toprepare nanostructured porous TE films by preserving the size and morphologyof the as-synthesized bismuth chalcogenide particles. A new glass based substrate is designed and fabricated to study the electronic transportproperties of the electrically active films prepared via EPD. Using this platform,we could clearly demonstrate the significance of the synthetic methodon the surface chemistry and resultant transport properties of the TE materials.The methods and materials developed in this thesis are expected toimpact and expedite further developments in the field of thermoelectrics.
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15.
  • Costa, A. L., et al. (författare)
  • Eco design for Ag-based solutions against SARS-CoV-2 and E. coli
  • 2022
  • Ingår i: Environmental Science: Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 9:11, s. 4295-4304
  • Tidskriftsartikel (refereegranskat)abstract
    • For the first time, we exploited the antiviral and antibacterial properties of Ag NPs stabilised by quaternized hydroxyethyl cellulose (Ag-HEC) against SARS-CoV-2 and Escherichia coli through an eco-friendly process at room temperature in three different environments: 1) water, where Ag was dispersed as a nanosol, 2) textiles, where Ag was applied as a coating, and 3) hydrogel where Ag is embedded. The antiviral performance of Ag-HEC nanosols was quantified through the selectivity index (SI), defined as the ratio between 50% cytotoxic and inhibitory concentration, in order to evaluate the ability to be active in a concentration range below the cytotoxicity value. The collected results pointed out an actual enhanced risk/benefit profile of Ag-HEC NPs with respect to chloroquine, with an SI of 22.2 and 8.4, respectively. Antibacterial and antiviral activities of Ag-HEC NPs immobilized on textiles or mucosa-like hydrogels were also assessed and their efficacy in potential application as protective clothing or nasal molecular masks was verified. This work demonstrated that a modern, safe and sustainable design allows traditional colloidal silver-based technologies to be efficiently exploited for a broad spectrum of antimicrobial solutions against bacterial and viral infections.
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16.
  • Demirci, Yunus, et al. (författare)
  • The Effect of Crystal Mismatch on the Thermoelectric Performance Enhancement of Nano Cu2Se
  • 2021
  • Ingår i: FRONTIERS IN MATERIALS. - : Frontiers Media SA. - 2296-8016. ; 7
  • Tidskriftsartikel (refereegranskat)abstract
    • In the past decades, Cu2-x Se compounds have attracted great attention due to the inclusion of non-toxic and abundant elements, besides having a promising thermoelectric (TE) performance. In this work, we investigated the effect of a crystal mismatch of a nanoinclusion phase on the TE properties of Cu2-x Se. Nano-Cu2Se was synthesized using microwave assisted thermolysis, while the p-type skutterudite, Fe3.25Co0.75Sb12 (FeCoSb), compound was synthesized using a chemical alloying route. Nano-Cu2Se, and (nano-Cu2Se)(1-x )(nano-FeCoSb)( x ) composites, where x = 0.05 and 0.1, were prepared via mechanical alloying followed by Spark Plasma Sintering process. Structural properties were evaluated by PXRD and SEM analysis, while the high temperature transport properties were examined via electrical conductivity, Seebeck coefficient, and thermal conductivity measurements in the temperature range of 300-800 K. Powder X-ray diffraction (PXRD) confirmed a single phase of nano Cu2Se, while the samples with FeCoSb inclusion consist of two phases as Cu2Se and CoSb3. SEM micrographs of all samples show that Cu2Se has randomly oriented grains with different sizes. Cu2Se samples with a FeCoSb inclusion show a rather different structure. In these samples, a rod-shaped FeCoSb phase, with a size varying between 20 and 100 nm, showed an inhomogeneous distribution in the structure and stacked between the Cu2Se layers. Transport data indicate that crystal mismatch between Cu2Se and FeCoSb has a strong effect on the TE transport properties. Electrical conductivity decreases but Seebeck coefficient enhances with nano FeCoSb inclusion. Total thermal conductivity was suppressed by 30% and ZT value enhanced by 15% with 5% nano FeCoSb inclusion at 750 K, likely due to a decrease in the electronic contribution of the thermal conductivity. Structural and transport data show that small amount of nanoinclusion of FeCoSb has a beneficial effect on the TE performance of nano Cu2Se at temperatures below 800 K.
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17.
  • Du, Yong, et al. (författare)
  • Investigation of the Heteroepitaxial Process Optimization of Ge Layers on Si (001) by RPCVD
  • 2021
  • Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 11:4
  • Tidskriftsartikel (refereegranskat)abstract
    • This work presents the growth of high-quality Ge epilayers on Si (001) substrates using a reduced pressure chemical vapor deposition (RPCVD) chamber. Based on the initial nucleation, a low temperature high temperature (LT-HT) two-step approach, we systematically investigate the nucleation time and surface topography, influence of a LT-Ge buffer layer thickness, a HT-Ge growth temperature, layer thickness, and high temperature thermal treatment on the morphological and crystalline quality of the Ge epilayers. It is also a unique study in the initial growth of Ge epitaxy; the start point of the experiments includes Stranski-Krastanov mode in which the Ge wet layer is initially formed and later the growth is developed to form nuclides. Afterwards, a two-dimensional Ge layer is formed from the coalescing of the nuclides. The evolution of the strain from the beginning stage of the growth up to the full Ge layer has been investigated. Material characterization results show that Ge epilayer with 400 nm LT-Ge buffer layer features at least the root mean square (RMS) value and it's threading dislocation density (TDD) decreases by a factor of 2. In view of the 400 nm LT-Ge buffer layer, the 1000 nm Ge epilayer with HT-Ge growth temperature of 650 degrees C showed the best material quality, which is conducive to the merging of the crystals into a connected structure eventually forming a continuous and two-dimensional film. After increasing the thickness of Ge layer from 900 nm to 2000 nm, Ge surface roughness decreased first and then increased slowly (the RMS value for 1400 nm Ge layer was 0.81 nm). Finally, a high-temperature annealing process was carried out and high-quality Ge layer was obtained (TDD=2.78 x 10(7) cm(-2)). In addition, room temperature strong photoluminescence (PL) peak intensity and narrow full width at half maximum (11 meV) spectra further confirm the high crystalline quality of the Ge layer manufactured by this optimized process. This work highlights the inducing, increasing, and relaxing of the strain in the Ge buffer and the signature of the defect formation.
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18.
  • Gholizadeh, Armin, et al. (författare)
  • Facile synthesis of nanographene by a high-yield and scalable method
  • 2020
  • Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 46:14, s. 22861-22868
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this work was to synthesize nanographene (NG) through a simple, efficient, and cost-effective method. In this regard, a combination of microwave (MW) and shear mixing with a kitchen blender was used. Atomic force microscopy (AFM), Raman spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis were used to investigate the structure of synthesized NG. The Results of the characterizations demonstrated that most of the synthesized NG exhibited OD structure and bilayer characteristics. The obtained results introduce a method for synthesizing NG at a large scale through a combination of MW and shear, in a relatively short time, without any need for purification.
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19.
  • Gupta, Govind, et al. (författare)
  • Silver nanoparticles with excellent biocompatibility block pseudotyped SARS-CoV-2 in the presence of lung surfactant
  • 2022
  • Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media SA. - 2296-4185. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Silver (Ag) is known to possess antimicrobial properties which is commonly attributed to soluble Ag ions. Here, we showed that Ag nanoparticles (NPs) potently inhibited SARS-CoV-2 infection using two different pseudovirus neutralization assays. We also evaluated a set of Ag nanoparticles of different sizes with varying surface properties, including polyvinylpyrrolidone (PVP)-coated and poly (ethylene glycol) (PEG)-modified Ag nanoparticles, and found that only the bare (unmodified) nanoparticles were able to prevent virus infection. For comparison, TiO2 nanoparticles failed to intercept the virus. Proteins and lipids may adsorb to nanoparticles forming a so-called bio-corona; however, Ag nanoparticles pre-incubated with pulmonary surfactant retained their ability to block virus infection in the present model. Furthermore, the secondary structure of the spike protein of SARS-CoV-2 was perturbed by the Ag nanoparticles, but not by the ionic control (AgNO3) nor by the TiO2 nanoparticles. Finally, Ag nanoparticles were shown to be non-cytotoxic towards the human lung epithelial cell line BEAS-2B and this was confirmed by using primary human nasal epithelial cells. These results further support that Ag nanoparticles may find use as anti-viral agents.
  •  
20.
  • Hamawandi, Bejan, PhD, et al. (författare)
  • A Comparative Study on the Thermoelectric Properties of Bismuth Chalcogenide Alloys Synthesized through Mechanochemical Alloying and Microwave-Assisted Solution Synthesis Routes
  • 2020
  • Ingår i: Frontiers in Materials. - : Frontiers Media S.A.. - 2296-8016. ; 7
  • Tidskriftsartikel (refereegranskat)abstract
    • The way a material is synthesized and processed has an immense effect on its microstructure, which in turn has a big impact on its transport properties. Here, we compare the thermoelectric (TE) properties of n- and p-type Bi2−xSbxTe3 (x: 0 and 1.5) materials synthesized through two different routes, specifically mechanochemical alloying (MA)—as a solid-state synthesis route—and microwave(MW)-assisted polyol synthesis—as a solution synthesis route. Reaction time is significantly reduced in the MW synthesis, leading to significantly lower energy consumption (i.e., higher energy efficiency) per batch than using the MA route. The resultant materials are compared for their crystallinity, phase purity, morphology, and microstructure. Spark plasma sintering was used to prepare pellets, and the resultant consolidates were evaluated for their transport properties. TE properties and microstructure of the specimens were investigated in relation to processing conditions and composition. MA samples formed fused structures (from 200 nm to several micrometers in size) composed of smaller particles. MW-synthesized materials exhibited hexagonal platelet morphology, high crystallinity, and phase purity. They also showed lower thermal conductivity, leading to a higher resultant TE figure-of-merit ZT. TE properties of Bi2−xSbxTe3 samples were studied on sintered cylindrical pellet samples, where the highest ZT values achieved were 1.04 (at 440 K) for MW-Bi2Te3 and 0.76 (at 523 K) for MW-Bi0.5Sb1.5Te3 samples, while MA-Bi2Te3 and MA-Bi0.5Sb1.5Te3 samples showed maximum ZT values of 0.74 (at 460 K) and 0.27 (at 300 K), respectively, as n- and p-type TE materials. The observed trend is much higher ZT values for MW samples, ascribed to their higher degree of texturing and nanostructured grains reducing the thermal conductivity, thus achieving a better overall performance, verifying the prospect to enhance ZT using MW-assisted solution synthesis approach.
  •  
21.
  • Hamawandi, Bejan, PhD (författare)
  • Design, Synthesis and Characterization of Nanostructured Thermoelectric Materials
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The demand for energy is rapidly increasing, triggering more carbon emission and global warming. Alternative green energy sources are essential to secure the future generation from the effect of pollution and global warming. During the last few decades, thermoelectric (TE) materials gained interest, due to their capability of directly interconverting between heat and power, which can be used to convert waste heat to electricity.  One of the strategic TE adaptation approaches is to develop high efficiency TE materials from earth-abundant and non-toxic components. Not only the TE materials’ composition, but also the synthesis method, has to be environment friendly in order to create a green transition, with minimum adverse environmental impacts. Bottom-up microwave (MW) assisted synthesis routes, using water and polyalcohol as green solvents were demonstrated feasible to generate binary and ternary compositions of Bi2-xSbxTe3, which were effective in room temperature. A more earth abundant and environment friendly material composition, copper selenide (Cu2-XSe), effective at intermediate temperature regime (200-600 °C), was synthesized by MW-assisted thermolysis. The synthesized materials were characterized in terms of structure, microstructure, surface chemistry and TE transport properties, and showed significant improvement of TE performance compared to materials synthesized using conventional methods - mainly attributed to the preservation of nanostructure. Significant results have been achieved with improved material characteristics, while the time and the energy investment were substantially reduced. The developed processes with reduced time and carbon footprint offer excellent sustainable synthesis routes for large-scale synthesis of high-performance nanostructured TE materials as strategic energy materials. 
  •  
22.
  • Hamawandi, Bejan, PhD, et al. (författare)
  • Facile Solution Synthesis, Processing and Characterization of n- and p-Type Binary and Ternary Bi-Sb Tellurides
  • 2020
  • Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 10:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The solution synthesis route as a scalable bottom-up synthetic method possesses significant advantages for synthesizing nanostructured bulk thermoelectric (TE) materials with improved performance. Tuning the composition of the materials directly in the solution, without needing any further processing, is important for adjusting the dominant carrier type. Here, we report a very rapid (2 min) and high yield (>8 g/batch) synthetic method using microwave-assisted heating, for the controlled growth of Bi2-xSbxTe3 (x: 0-2) nanoplatelets. Resultant materials exhibit a high crystallinity and phase purity, as characterized by XRD, and platelet morphology, as revealed by SEM. Surface chemistry of as-made materials showed a mixture of metallic and oxide phases, as evidenced by XPS. Zeta-potential analysis exhibited a systematic change of isoelectric point as a function of the material composition. As-made materials were directly sintered into pellets by using spark plasma sintering process. TE performance of Bi2-xSbxTe3 pellets were studied, where the highest ZT values of 1.04 (at 440 K) for Bi2Te3 and 1.37 (at 523 K) for Sb2Te3 were obtained, as n- and p-type TE materials. The presented microwave-assisted synthesis method is energy effective, a truly scalable and reproducible method, paving the way for large scale production and implementation of towards large-area TE applications.
  •  
23.
  • Hamawandi, Bejan, PhD, et al. (författare)
  • Minute-Made, High-Efficiency Nanostructured Bi2Te3 via High-Throughput Green Solution Chemical Synthesis
  • 2021
  • Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 11:8
  • Tidskriftsartikel (refereegranskat)abstract
    • Scalable synthetic strategies for high-quality and reproducible thermoelectric (TE) materials is an essential step for advancing the TE technology. We present here very rapid and effective methods for the synthesis of nanostructured bismuth telluride materials with promising TE performance. The methodology is based on an effective volume heating using microwaves, leading to highly crystalline nanostructured powders, in a reaction duration of two minutes. As the solvents, we demonstrate that water with a high dielectric constant is as good a solvent as ethylene glycol (EG) for the synthetic process, providing a greener reaction media. Crystal structure, crystallinity, morphology, microstructure and surface chemistry of these materials were evaluated using XRD, SEM/TEM, XPS and zeta potential characterization techniques. Nanostructured particles with hexagonal platelet morphology were observed in both systems. Surfaces show various degrees of oxidation, and signatures of the precursors used. Thermoelectric transport properties were evaluated using electrical conductivity, Seebeck coefficient and thermal conductivity measurements to estimate the TE figure-of-merit, ZT. Low thermal conductivity values were obtained, mainly due to the increased density of boundaries via materials nanostructuring. The estimated ZT values of 0.8-0.9 was reached in the 300-375 K temperature range for the hydrothermally synthesized sample, while 0.9-1 was reached in the 425-525 K temperature range for the polyol (EG) sample. Considering the energy and time efficiency of the synthetic processes developed in this work, these are rather promising ZT values paving the way for a wider impact of these strategic materials with a minimum environmental impact.
  •  
24.
  • Jermy, B. Rabindran, et al. (författare)
  • Targeted therapeutic effect against the breast cancer cell line MCF-7 with a CuFe2O4/silica/cisplatin nanocomposite formulation
  • 2019
  • Ingår i: Beilstein Journal of Nanotechnology. - : BEILSTEIN-INSTITUT. - 2190-4286. ; 10, s. 2217-2228
  • Tidskriftsartikel (refereegranskat)abstract
    • The combination of magnetic nanoparticles with a porous silica is a composite that has attracted significant attention for potential multifunctional theranostic applications. In this study, 30 wt % CuFe2O4 was impregnated into a matrix of monodispersed spherical hydrophilic silica (HYPS) nanoparticles through a simple dry impregnation technique. The chemotherapy drug cisplatin was loaded through electrostatic equilibrium adsorption over 24 h in normal saline solution. The presence of cubic spinel CuFe2O4 on HYPS was confirmed through powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and diffuse reflectance UV-vis spectroscopy (DR UV-vis) analysis. The HYPS particles showed a surface area of 170 m(2)/g, pore size of 8.3 nm and pore volume of 0.35 cm(3)/g. The cisplatin/CuFe2O4/HYPS nanoformulation showed the accumulation of copper ferrite nanoparticles on the surface and in the pores of HYPS with a surface area of 45 m(2)/g, pore size of 16 nm and pore volume of 0.18 cm(3)/g. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) mapping analysis showed the presence of homogeneous silica particles with nanoclusters of copper ferrite distributed on the HYPS support. Vibrating sample magnetometry (VSM) analysis of CuFe2O4/HYPS showed paramagnetic behavior with a saturated magnetization value of 7.65 emu/g. DRS UV-vis analysis revealed the functionalization of cisplatin in tetrahedral and octahedral coordination in the CuFe2O4/HYPS composite. Compared to other supports such as mesocellular foam and silicalite, the release of cisplatin using the dialysis membrane technique was found to be superior when CuFe2O4/HYPS was applied as the support. An in vitro experiment was conducted to determine the potential of CuFe2O4/HYPS as an anticancer agent against the human breast cancer cell line MCF-7. The results show that the nanoparticle formulation can effectively target cancerous cells and could be an effective tumor imaging guide and drug delivery system.
  •  
25.
  • Karlsson, Hanna L., et al. (författare)
  • Toxicity of Metal and Metal Oxide Nanoparticles
  • 2015
  • Ingår i: Handbook on the Toxicology of Metals: Fourth Edition. - : Elsevier BV. ; , s. 75-112
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • Engineered nanomaterials hold great potential in many sectors of society, not least in medicine. However, the increasing production and use of engineered nanomaterials also raises concerns about inadvertent exposure and the potential for adverse effects on human health and the environment. This chapter provides an overview of metal and metal oxide nanoparticles, their applications, and the potential for human exposure. This is followed by a discussion of general principles of nanoparticle-induced toxicity and methods for toxicity testing of nanomaterials. Careful assessment of the material properties is required for a full understanding of nanomaterial toxicity; a section of the chapter is therefore devoted to physicochemical characterization. This is followed by a detailed description of the current knowledge concerning 12 of the most important metal and metal oxide nanoparticles, with a systematic evaluation of invitro (cell culture) and invivo (animal) toxicity studies. Ecotoxicological effects are not discussed because the chapter is focused on implications for human health.
  •  
26.
  • Karlsson, H. L., et al. (författare)
  • Toxicity of metal and metal oxide nanoparticles
  • 2021
  • Ingår i: Handbook on the Toxicology of Metals: Volume I: General Considerations. - : Elsevier BV. ; , s. 87-126
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • Engineered nanomaterials hold great potential in many sectors of society, not least in medicine. However, the increasing production and use of engineered nanomaterials also raises concerns regarding inadvertent exposure and the potential for adverse effects on human health. The chapter provides an overview of metal and metal oxide nanoparticles, their principal applications, and the potential for human exposure. This is followed by a discussion of general principles of nanoparticle-induced toxicity and methods for toxicity testing of nanomaterials. Careful characterization of material properties is required for a full understanding of nanomaterial toxicity and a section of the chapter is devoted to physicochemical characterization. This is followed by a comprehensive description of the most common metal and metal oxide nanoparticles, with a systematic evaluation of in vitro and in vivo toxicity studies. Finally, an overview of emerging, two-dimensional (2D) metal nanomaterials is provided.
  •  
27.
  • Kertmen, Ahmet, et al. (författare)
  • Acetate-Induced Disassembly of Spherical Iron Oxide Nanoparticle Clusters into Monodispersed Core-Shell Structures upon Nanoemulsion Fusion
  • 2017
  • Ingår i: Langmuir. - : AMER CHEMICAL SOC. - 0743-7463 .- 1520-5827. ; 33:39, s. 10351-10365
  • Tidskriftsartikel (refereegranskat)abstract
    • It has been long known that the physical encapsulation of oleic acid-capped iron oxide nanoparticles (OA-IONPs) with the cetyltrimethylammonium (CTA(+)) surfactant induces the formation of spherical iron oxide nanoparticle clusters (IONPCs). However, the behavior and functional properties of IONPCs in chemical reactions have been largely neglected and are still not well-understood. Herein, we report an unconventional ligand-exchange function of IONPCs activated when dispersed in an ethyl acetate/acetate buffer system. The ligand exchange can successfully transform hydrophobic OA-IONP building blocks of IONPCs into highly hydrophilic, acetate-capped iron oxide nanoparticles (Ac-IONPs). More importantly, we demonstrate that the addition of silica precursors (tetraethyl orthosilicate and 3-aminopropyltriethoxysilane) to the acetate/oleate ligand-exchange reaction of the IONPs induces the disassembly of the IONPCs into monodispersed iron oxide-acetate-silica core-shell-shell (IONPs@acetate@SiO2) nanoparticles. Our observations evidence that the formation of IONPs@acetate@SiO2 nanoparticles is initiated by a unique micellar fusion mechanism between the Pickering-type emulsions of IONPCs and nanoemulsions of silica precursors formed under ethyl acetate buffered conditions. A dynamic rearrangement of the CTA(+)-oleate bilayer on the IONPC surfaces is proposed to be responsible for the templating process of the silica shells around the individual IONPs. In comparison to previously reported methods in the literature, our work provides a much more detailed experimental evidence of the silica-coating mechanism in a nanoemulsion system. Overall, ethyl acetate is proven to be a very efficient agent for an effortless preparation of monodispersed IONPs@acetate@SiO2 and hydrophilic Ac-IONPs from IONPCs.
  •  
28.
  • Khan, A., et al. (författare)
  • Holographic recording in cross-linked polymeric matrices through photoacid generation
  • 2008
  • Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 20:11, s. 3669-3674
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a novel strategy for writing volume holograms by photoacid generation and subsequent acid-catalyzed degradation leading to increased free volume/refractive index modulation in the exposed regions of a cross-linked rigid polymeric matrix. This strategy offers nondestructive read out and high diffraction efficiency and allows optical-quality, millimeter thick films to be fabricated that possess excellent thermal and dimensional stability. A key feature of this approach is the efficient acid-catalyzed degradation of functional groups in the cross-linked matrix leading to release of volatile products which diffuse readily out of the thick films. Furthermore, the reported data storage material is lightweight and inexpensive and can be easily processed into different shapes, making it an attractive candidate for data storage applications.
  •  
29.
  • Kilic, Nuzhet I., et al. (författare)
  • Two-Photon Polymerization Printing with High Metal Nanoparticle Loading
  • 2023
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 15:42, s. 49794-49804
  • Tidskriftsartikel (refereegranskat)abstract
    • Two-photon polymerization (2PP) is an efficient technique to achieve high-resolution, three-dimensional (3D)-printed complex structures. However, it is restricted to photocurable monomer combinations, thus presenting constraints when aiming at attaining functionally active resist formulations and structures. In this context, metal nanoparticle (NP) integration as an additive can enable functionality and pave the way to more dedicated applications. Challenges lay on the maximum NP concentrations that can be incorporated into photocurable resist formulations due to the laser-triggered interactions, which primarily originate from laser scattering and absorption, as well as the limited dispersibility threshold. In this study, we propose an approach to address these two constraints by integrating metallic Rh NPs formed ex situ, purposely designed for this scope. The absence of surface plasmon resonance (SPR) within the visible and near-infrared spectra, coupled with the limited absorption value measured at the laser operating wavelength (780 nm), significantly limits the laser-induced interactions. Moreover, the dispersibility threshold is increased by engineering the NP surface to be compatible with the photocurable resin, permitting us to achieve concentrations of up to 2 wt %, which, to our knowledge, is significantly higher than the previously reported limit (or threshold) for embedded metal NPs. Another distinctive advantage of employing Rh NPs is their role as promising contrast agents for X-ray fluorescence (XRF) bioimaging. We demonstrated the presence of Rh NPs within the whole 2PP-printed structure and emphasized the potential use of NP-loaded 3D-printed nanostructures for medical devices.
  •  
30.
  •  
31.
  • Kördel, Mikael, et al. (författare)
  • Quantitative conversion of biomass in giant DNA virus infection
  • 2021
  • Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Bioconversion of organic materials is the foundation of many applications in chemical engineering, microbiology and biochemistry. Herein, we introduce a new methodology to quantitatively determine conversion of biomass in viral infections while simultaneously imaging morphological changes of the host cell. As proof of concept, the viral replication of an unidentified giant DNA virus and the cellular response of an amoebal host are studied using soft X-ray microscopy, titration dilution measurements and thermal gravimetric analysis. We find that virions produced inside the cell are visible from 18 h post infection and their numbers increase gradually to a burst size of 280-660 virions. Due to the large size of the virion and its strong X-ray absorption contrast, we estimate that the burst size corresponds to a conversion of 6-12% of carbonaceous biomass from amoebal host to virus. The occurrence of virion production correlates with the appearance of a possible viral factory and morphological changes in the phagosomes and contractile vacuole complex of the amoeba, whereas the nucleus and nucleolus appear unaffected throughout most of the replication cycle.
  •  
32.
  • Lalegani, Z., et al. (författare)
  • Modeling, design, and synthesis of gram-scale monodispersed silver nanoparticles using microwave-assisted polyol process for metamaterial applications
  • 2020
  • Ingår i: Optical materials (Amsterdam). - : Elsevier BV. - 0925-3467 .- 1873-1252. ; 108
  • Tidskriftsartikel (refereegranskat)abstract
    • High-yield monodispersed silver (Ag) nanospheres were modeled, designed, and synthesized by microwaveassisted (MW-assisted) polyol method from AgNO3, polyvinyl pyrrolidone (PVP), and ethylene glycol (EG), as precursors, at 145 degrees C within a short reaction time of 2 min, and the results were compared to those of conventional polyol method. Maintaining the PVP:AgNO3 molar ratio, the effect of increasing the amounts of AgNO3 and PVP at a constant amount of EG (40 mL) on the final product was evaluated. The synthesized nanoparticles (NPs) were characterized by SEM, UV-Vis spectroscopy, FTIR and DLS analysis. The results showed that with increasing the amount of AgNO3 to 0.5 and 1 g, monodispersed Ag nanoparticles (Ag NPs) with particle sizes of 54 and 61 nm were formed, as per the plasmon absorption peaks at 436 and 442 nm, respectively. Moreover, using 40 mL of the EG solution, we could obtain a high yield of the NPs (similar to 90%). The sub-gram yield was excellently high, offering great opportunities for commercializing the procedure. Also, the proposed study paves a new way for Ag NPs realization for different practical applications ranging from MW to optics.
  •  
33.
  • Lalegani, Z., et al. (författare)
  • Targeted dielectric coating of silver nanoparticles with silica to manipulate optical properties for metasurface applications
  • 2022
  • Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 287, s. 126250-
  • Tidskriftsartikel (refereegranskat)abstract
    • An epsilon-negative metamaterial (ENM) containing core@shell nanoparticles (NPs) was designed, where silver (Ag) NPs served as core and silica (SiO2) was used as spacer shell. AgNPs were synthesized in large scale, using microwave-assisted polyol method, in three average particle sizes, as 30, 54, and 61 nm, with a narrow particle size distribution. Optical absorption of Ag NPs was investigated using UV-Vis spectroscopy. Their optical behavior was also theoretically predicted for different thicknesses of the SiO2 shell immersed in media of different refractive indices using the Clausius Mossotti equation. Based on the results, optimal outputs were obtained with a SiO2 shell of 10 nm in thickness encompassing 54 nm Ag NPs based on the analytical model and numerical simulations here developed for core-shell structures. Then 10 nm SiO2 shell was grown on 54 nm Ag NPs by sol-gel synthesis. The NPs were then characterized by UV-Vis, TEM, SEM, EDX, DLS, and zeta potential analyses. The synthesized core-shell NPs can be used to establish epsilon-negative properties in polymer layers within visible range of wavelengths.
  •  
34.
  • Larsson, Jakob C., et al. (författare)
  • High-spatial-resolution x-ray fluorescence tomography with spectrally matched nanoparticles
  • 2018
  • Ingår i: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 63, s. 164001-
  • Tidskriftsartikel (refereegranskat)abstract
    • Present macroscopic biomedical imaging methods provide either morphology with high spatial resolution (e.g. CT) or functional/molecular information with lower resolution (e.g. PET). X-ray fluorescence (XRF) from targeted nanoparticles allows molecular or functional imaging but sensitivity has so far been insufficient resulting in low spatial resolution, despite long exposure times and high dose. In the present paper, we show that laboratory XRF tomography with metal-core nanoparticles (NPs) provides a path to functional/molecular biomedical imaging with ~100 µm resolution in living rodents. The high sensitivity and resolution rely on the combination of a high-brightness liquid-metal-jet x-ray source, pencil-beam optics, photon-counting energy-dispersive detection, and spectrally matched NPs. The method is demonstrated on mice for 3D tumor imaging via passive targeting of in-house-fabricated molybdenum NPs. Exposure times, nanoparticle dose, and radiation dose agree well with in vivo imaging.
  •  
35.
  • Li, Shanghua, 1980-, et al. (författare)
  • Nanocomposites of polymer and inorganic nanoparticles for optical and magnetic applications
  • 2010
  • Ingår i: Nano reviews. - : CoAction Publishing. - 2000-5121. ; 1, s. 5214-
  • Tidskriftsartikel (refereegranskat)abstract
    • This article provides an up-to-date review on nanocomposites composed of inorganic nanoparticles and the polymer matrix for optical and magnetic applications. Optical or magnetic characteristics can change upon the decrease of particle sizes to very small dimensions, which are, in general, of major interest in the area of nanocomposite materials. The use of inorganic nanoparticles into the polymer matrix can provide high-performance novel materials that find applications in many industrial fields. With this respect, frequently considered features are optical properties such as light absorption (UV and color), and the extent of light scattering or, in the case of metal particles, photoluminescence, dichroism, and so on, and magnetic properties such as superparamagnetism, electromagnetic wave absorption, and electromagnetic interference shielding. A general introduction, definition, and historical development of polymer-inorganic nanocomposites as well as a comprehensive review of synthetic techniques for polymer-inorganic nanocomposites will be given. Future possibilities for the development of nanocomposites for optical and magnetic applications are also introduced. It is expected that the use of new functional inorganic nano-fillers will lead to new polymer-inorganic nanocomposites with unique combinations of material properties. By careful selection of synthetic techniques and understanding/exploiting the unique physics of the polymeric nanocomposites in such materials, novel functional polymer-inorganic nanocomposites can be designed and fabricated for new interesting applications such as optoelectronic and magneto-optic applications.
  •  
36.
  • Li, Yuyang (författare)
  • Synthesis and Characterization of Nanoprobes for X-Ray Fluorescence Computed Tomography (XFCT) Bio-imaging
  • 2020
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • X-ray fluorescence computed tomography (XFCT) is an emerging biomedical imaging technique. The KTH-XFCT laboratory system offers a characteristic 24 keV emission line, and high spatial resolution (200 ?m) images. XFCT as a newly emerging modality also requires the exploration and development of suitable contrast agents. Nanomaterials have been widely used as contrast agents in many popular imaging modalities like MRI, PET, and CT. They have several advantages including long blood circulation time, high ratio of surface area to volume, and enhanced image contrast. However, the use of nanomaterials as contrast agents is limited by their biocompatibility and toxicity, which are determined by the physicochemical properties including size, morphology, surface chemistry. Therefore, the study on the synthesis and characterization of nanomaterials is an indispensable step. In this thesis, a group of elements (Y, Zr, Nb, Ru, Rh) are selected based on the X-ray K?-absorption energy, matching with the 24 keV emission line of KTH-XFCT source. Y, Zr, Nb, Ru and Rh based nanoparticles are synthesized by hydrothermal and polyol method, identified as the ceramic and metallic groups. XRF performance is demonstrated by the XFCT system. Metallic Ru and Rh nanoparticles are further selected to study the synthesis conditions and in vitro toxicity for their smaller TEM and hydrodynamic size. Surface properties are investigated to show the isoelectric point and polymer coating on the metallic nanoparticles. Morphological different Rh nanoparticles are obtained by introducing different additives during the synthesis, indicating the different cytotoxicity performance attributed to different morphologies. Silica coating is further performed on the surface of metallic and metallic nanoparticles to improve their biocompatibility. The in vitro toxicity assessment are performed on the murine macrophages and human ovarian cancer cell lines. X-ray fluorescence performance is evaluated for each nanoparticles by using soft-tissue equivalent holder and in situ small-animal imaging experiments. The results indicates the spatial resolution and detection sensitivity of the concentration of the metallic nanoparticles. In this work, we demonstrate the potential of a group selected nanomaterials as XFCT contrast agents for the first time, especially, investigate the synthesis, surface properties, in vitro toxicity as well as detection sensitivity of the metallic nanoparticles.
  •  
37.
  • Li, Yuyang, et al. (författare)
  • Synthesis and Cytotoxicity Studies on Ru and Rh Nanoparticles as Potential X-Ray Fluorescence Computed Tomography (XFCT) Contrast Agents
  • 2020
  • Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:2
  • Tidskriftsartikel (refereegranskat)abstract
    • X-Ray fluorescence computed tomography (XFCT) is an emerging biomedical imaging technique, which demands the development of new contrast agents. Ruthenium (Ru) and rhodium (Rh) have spectrally attractive K ff edge energies, qualifying them as new XFCT bio-imaging probes. Metallic Ru and Rh nanoparticles are synthesized by polyol method, in the presence of a stabilizer. The effect of several reaction parameters, including reaction temperature time, precursor and stabilizer concentration, and stabilizer molecular weight, on the size of particles, were studied. Resultant materials were characterized in detail using XRD, TEM, FT-IR, DLS-zeta potential and TGA techniques. Ru particles in the size range of 1-3 nm, and Rh particles of 6-9 nm were obtained. At physiological pH, both material systems showed agglomeration into larger assemblies ranging from 12-104 nm for Ru and 25-50 nm for Rh. Cytotoxicity of the nanoparticles (NPs) was evaluated on macrophages and ovarian cancer cells, showing minimal toxicity in doses up to 50 mu g/mL. XFCT performance was evaluated on a small-animal-sized phantom model, demonstrating the possibility of quantitative evaluation of the measured dose with an expected linear response. This work provides a detailed route for the synthesis, size control and characterization of two materials systems as viable contrast agents for XFCT bio-imaging.
  •  
38.
  • Li, Yuyang, et al. (författare)
  • Synthesis, Physicochemical Characterization, and Cytotoxicity Assessment of Rh Nanoparticles with Different Morphologies-as Potential XFCT Nanoprobes
  • 2020
  • Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:11, s. 2129-2129
  • Tidskriftsartikel (refereegranskat)abstract
    • Morphologically controllable synthesis of Rh nanoparticles (NPs) was achieved by the use of additives during polyol synthesis. The effect of salts and surfactant additives including PVP, sodium acetate, sodiumcitrate, CTAB,CTAC,andpotassiumbromideonRhNPsmorphologywasinvestigated. When PVP was used as the only additive, trigonal NPs were obtained. Additives containing Br− ions (CTAB and KBr) resulted in NPs with a cubic morphology, while those with carboxyl groups (sodium citrate and acetate) formed spheroid NPs. The use of Cl− ions (CTAC) resulted in a mixture of polygon morphologies. Cytotoxicity of these NPs was evaluated on macrophages and ovarian cancer cell lines. Membrane integrity and cellular activity are both influenced to a similar extent, for both the cell lines, with respect to the morphology of Rh NPs. The cells exposed to trigonal Rh NPs showed the highest viability, among the NP series. Particles with a mixed polygon morphology had the highest cytotoxic impact, followed by cubic and spherical NPs. The Rh NPs were further demonstrated as contrast agents for X-ray fluorescence computed tomography (XFCT) in a small-animal imaging setting. This work provides a detailed route for the synthesis, morphology control, and characterization of Rh NPs as viable contrast agents for XFCT bio-imaging. 
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39.
  • Lobov, Gleb, et al. (författare)
  • Electro-optical effects of high aspect ratio P3HT nanofibers colloid in polymer micro-fluid cells
  • 2017
  • Ingår i: Optics Letters. - : OSA Publishing. - 0146-9592 .- 1539-4794. ; 42:11, s. 2157-2160
  • Tidskriftsartikel (refereegranskat)abstract
    • This Letter reports the electro-optical (EO) effect of Poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofibers colloid in a polymer micro-fluidic EO cell. P3HT nanofibers are high aspect ratio semiconducting nanostructures, and can be collectively aligned by an external alternating electric field. Optical transmission modulated by the electric field is a manifestation of the electro-optical effect due to high inner crystallinity of P3HT nanofibers. According to our results, the degree of alignment reaches a maximum at 0.6 V/μm of electric field strength, implying a big polarizability value due to geometry and electrical properties of P3HT nanofibers. We believe that one-dimensional crystalline organic nanostructures have a large potential in EO devices due to their significant anisotropy, wide variety of properties, low actuation voltages, and opportunity to be tailored via adjustment of the fabrication process.
  •  
40.
  • Mohamed, Alaaeldin, et al. (författare)
  • Photocatalytic degradation of organic dyes and enhanced mechanical properties of PAN/CNTs composite nanofibers
  • 2017
  • Ingår i: Separation and Purification Technology. - : Elsevier. - 1383-5866 .- 1873-3794. ; 182, s. 219-223
  • Tidskriftsartikel (refereegranskat)abstract
    • This work describes the enhanced mechanical properties of the composite nanofibers and the photodegradation of two organic dyes using PAN/CNTs under UV irradiation at different volume concentration (0.05, 0.1, 0.2, and 0.3 wt.%). The composite nanofibers was performed with polyacrylonitrile (PAN), and carbon nanotubes (CNTs) by electrospinning process. The composite nanofibers structure and morphology is characterized by XRD, FTIR, SEM, and TEM. The result indicates that with increasing CNTs content, the mechanical properties of the composite nanofibers was enhanced, and became more elastic, and the elastic modulus increased drastically. The results of mechanical properties exhibit improvements in tensile strengths, and elastic modulus by 38% and 84% respectively, at only 0.05 wt.% CNTs. Moreover, photocatalytic degradation performance in short time and low power intensity was achieved comparison to earlier reports.
  •  
41.
  • Mohamed, Alaa, et al. (författare)
  • Surface functionalized composite nanofibers for efficient removal of arsenic from aqueous solutions
  • 2017
  • Ingår i: Chemosphere. - : Elsevier Ltd. - 0045-6535 .- 1879-1298. ; 180, s. 108-116
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel composites nanofiber was synthesized based on PAN-CNT/TiO2-NH2 nanofibers using electrospinning technique followed by chemical modification of TiO2 NPs. PAN-CNT/TiO2-NH2 nanofiber were characterized by XRD, FTIR, SEM, and TEM. The effects of various experimental parameters such as initial concentration, contact time, and solution pH on As removal were investigated. The maximum adsorption capacity at pH 2 for As(III) and As(V) is 251 mg/g and 249 mg/g, respectively, which is much higher than most of the reported adsorbents. The adsorption equilibrium reached within 20 and 60 min as the initial solution concentration increased from 10 to 100 mg/L, and the data fitted well using the linear and nonlinear pseudo first and second order model. Isotherm data fitted well to the linear and nonlinear Langmuir, Freundlich, and Redlich-Peterson isotherm adsorption model. Desorption results showed that the adsorption capacity can remain up to 70% after 5 times usage. This work provides a simple and an efficient method for removing arsenic from aqueous solution.
  •  
42.
  • Muhammed, Mamoun, et al. (författare)
  • Nanostructured Skutterudites
  • 2006
  • Ingår i: Thermoelectrics Handbook. - : Taylor & Francis Group. - 0849322642 ; , s. 41-1-41-10
  • Bokkapitel (refereegranskat)
  •  
43.
  • Nikkam, Nader, et al. (författare)
  • Fabrication and thermo-physical properties characterization of ethylene glycol-MoS2 heat exchange fluids
  • 2017
  • Ingår i: International Communications in Heat and Mass Transfer. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0735-1933 .- 1879-0178. ; 89, s. 185-189
  • Tidskriftsartikel (refereegranskat)abstract
    • This study reports on the fabrication and thermo-physical properties evaluation of ethylene glycol (EG) based heat exchange fluids containing molybdenum disulfide nanoparticles (MoS2 NPs) and micrometer sized particles (MPs). For this purpose, MoS2 NPs and MPs (with average size of 90 nm and 1.2 mu m; respectively) were dispersed and stabilized in EG with particle loading of 0.25, 0.5, 1 wt%. To study the real effect of MoS2 NP/MP the use of surfactants was avoided and ultrasonic agitation was used for dispersion and preparation of stable MoS2 NFs/MFs. The objectives were investigation of impact of MoS2 particle size (including NP/MP) and particle loading on thermo-physical properties of EG based MoS2 NFs/MFs including thermal conductivity (TC) and viscosity of NFs/MFs at 20 degrees C. All suspensions (NFs/MFs) exhibited a higher TC than the EG as base liquid and NFs showed higher TC enhancement values than the MFs. A TC enhancement of 16.4% was observed for NFs containing 1 wt % MoS2 NPs while the maximum increase in viscosity of 9.7% was obtained for the same NF at 20 degrees C. It indicates this NF system may have some potential to be utilized in heat transfer applications.
  •  
44.
  • Noroozi, Mohammad, et al. (författare)
  • Fabrications of size-controlled SiGe nanowires using I-line lithography and focused ion beam technique
  • 2014
  • Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. ; , s. 167-174
  • Konferensbidrag (refereegranskat)abstract
    • In this study, a novel method using Focus Ion Beam (FIB) technique was applied to scale down Si1-xGex wires (x=0.27-0.57) to 20 nm width. Originally, the wires were processed by using Iline lithography and dry etching of SiGe on oxide (SGOI) substrates. The SGOI wafers were processed through condensation method where a SiGe/Si layer was grown in the beginning on SOI wafers and oxidized at 850-1050 °C. The shape of the nanowires (NWs) during the successive FIB cutting was examined by scanning electron microscopy (SEM) and the carrier transport through the NWs was checked by resistivity measurements. The contact resistance was reduced by Ni-silicide prior to metallization. The fabricated NWs were also suspended by tilting FIB. The results present the limitations and challenges of FIB technique to create NWs for advanced sensors and transistors.
  •  
45.
  • Oztan, Cagri Y., et al. (författare)
  • Thermoelectric performance of Cu2Se doped with rapidly synthesized gel-like carbon dots
  • 2021
  • Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 864
  • Tidskriftsartikel (refereegranskat)abstract
    • As an earth-abundant, inexpensive and non-toxic compound, Copper Selenide (Cu2Se) is a frequently investigated material for thermoelectric (TE) conversion applications. In this research, stoichiometric Cu2Se compounds were systematically doped with gel-like Carbon Dots (CDs), that were fabricated using a rapid and straightforward solvothermal method, at weight ratios of 2, 5 and 10%. The resultant ingots were spark plasma sintered and their TE performance was characterized. Scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDX) and powder X-ray diffraction (PXRD) were used to correlate the microstructure to the TE properties. Based on these measurements, CD doping strategy on Cu2Se yielded highly compacted, single phase grains with minimal oxidation. Characterization demonstrated a continuous enhancement of TE figure of merit (ZT) to a maximum of 2.1 at the optimum dopant ratio of 2 wt %. This enhancement was mainly due to the energy filtering effect of CD interfaces along the grain boundaries, and phonon scattering which increased the Seebeck coefficient and reduce the thermal conductivity. Doping beyond 2 wt% was recorded to inhibit this improvement. This research paved the path towards broader utilization of rapidly fabricated CDs to enhance TE conversion performance.
  •  
46.
  • Rajamani, Keerthivasan, et al. (författare)
  • Unlocking the Potential of Magnetic Refrigeration: Investigating the Compatibility of the Ga-Based Liquid Metal with a La(Fe,Mn,Si)13Hz Magnetocaloric Material for Enhanced Long-Term Stability
  • 2023
  • Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:51, s. 49027-49036
  • Tidskriftsartikel (refereegranskat)abstract
    • Magnetic refrigeration (MR) is a cutting-edge technology that promises high energy efficiency and eco-friendliness, making it an exciting alternative to traditional refrigeration systems. However, the main challenge to its widespread adoption is cost competitiveness. In this context, the use of liquid metals as heat transfer liquids in the MR has been proposed as a game-changing solution. Unfortunately, the toxicity and flammability of these liquid metals have raised serious concerns, limiting their practical use. In this study, we investigate the compatibility of a nontoxic and nonflammable GaInSn-based liquid metal with a magnetocaloric material, La(Fe,Mn,Si)13Hz, over a 1.5 year period. Our findings reveal nearly a 14% reduction in specific cooling energy and peak-specific isothermal magnetic entropy change for the considered magnetocaloric material. Our study provides valuable insights into the long-term stability of magnetocaloric materials and their compatibility with liquid metals, facilitating the development of more cost-effective and sustainable MR systems.
  •  
47.
  • Raslan, A., et al. (författare)
  • Modulation of conductivity of alginate hydrogels containing reduced graphene oxide through the addition of proteins
  • 2021
  • Ingår i: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 13:9, s. 1473-
  • Tidskriftsartikel (refereegranskat)abstract
    • Modifying hydrogels in order to enhance their conductivity is an exciting field with applications in cardio and neuro-regenerative medicine. Therefore, we have designed hybrid alginate hydrogels containing uncoated and protein-coated reduced graphene oxide (rGO). We specifically studied the adsorption of three different proteins, BSA, elastin, and collagen, and the outcomes when these protein-coated rGO nanocomposites are embedded within the hydrogels. Our results demon-strate that BSA, elastin, and collagen are adsorbed onto the rGO surface, through a non-spontaneous phenomenon that fits Langmuir and pseudo-second-order adsorption models. Protein-coated rGOs are able to preclude further adsorption of erythropoietin, but not insulin. Collagen showed better adsorption capacity than BSA and elastin due to its hydrophobic nature, although requiring more energy. Moreover, collagen-coated rGO hybrid alginate hydrogels showed an enhancement in conductivity, showing that it could be a promising conductive scaffold for regenerative medicine.
  •  
48.
  • Saladino, Giovanni, et al. (författare)
  • Carbon Quantum Dots Conjugated Rhodium Nanoparticles as Hybrid Multimodal Contrast Agents
  • 2021
  • Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 11:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Nanoparticle (NP)-based contrast agents enabling different imaging modalities are sought for non-invasive bio-diagnostics. A hybrid material, combining optical and X-ray fluorescence is presented as a bioimaging contrast agent. Core NPs based on metallic rhodium (Rh) have been demonstrated to be potential X-ray Fluorescence Computed Tomography (XFCT) contrast agents. Microwave-assisted hydrothermal method is used for NP synthesis, yielding large-scale NPs within a significantly short reaction time. Rh NP synthesis is performed by using a custom designed sugar ligand (LODAN), constituting a strong reducing agent in aqueous solution, which yields NPs with primary amines as surface functional groups. The amino groups on Rh NPs are used to directly conjugate excitation-independent nitrogen-doped carbon quantum dots (CQDs), which are synthesized through citrate pyrolysis in ammonia solution. CQDs provided the Rh NPs with optical fluorescence properties and improved their biocompatibility, as demonstrated in vitro by Real-Time Cell Analysis (RTCA) on a macrophage cell line (RAW 264.7). The multimodal characteristics of the hybrid NPs are confirmed with confocal microscopy, and X-ray Fluorescence (XRF) phantom experiments.
  •  
49.
  • Saladino, Giovanni, et al. (författare)
  • Click chemical assembly and validation of bio-functionalized superparamagnetic hybrid microspheres
  • 2020
  • Ingår i: Applied Nanoscience. - : Springer Nature. - 2190-5509 .- 2190-5517.
  • Tidskriftsartikel (refereegranskat)abstract
    • Surface derivatized magnetic nanoparticles have been commonly used for magnetic separation. Facile mechanisms are needed to be developed for the design of bio-functionalized magnetic hybrid materials, where the surfaces can be re-generated for the re-use of the developed platforms. Superparamagnetic iron oxide nanoparticles with a diameter below 10 nm were synthesized via a novel microwave-assisted hydrothermal method in the presence of citrate ions, which allowed to obtain uniform and negatively charged nanoparticles. These were then coupled with Poly-l-lysine (PLL), forming micrometer-sized self-assembled spherical entities. Cross-linking the PLL within these microspheres with glutaraldehyde stabilized them chemically and mechanically. The active bio-functionality was introduced by a protein grafting methodology, using m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (SMBS). The Moringa oleifera Coagulant Protein (MOCP) from a seed extract was employed for its characteristic coagulation activity. The performance of the MOCP functionalized microspheres was evaluated as a function of turbidity removal of problematic colloidal clay from water via magnetic separation, resulting in over 80% of activity within 15 min. Surface of these hybrid materials can be re-generated by treatment with alcohol, allowing their easy magnetic separation and re-use. The rapid and strong response with tunable magnetic property makes these hybrid microspheres a powerful tool for many potential applications, due to the general applicability of the developed methodology.
  •  
50.
  • Saladino, Giovanni, et al. (författare)
  • Iterative Nanoparticle Bioengineering Enabled by X-Ray Fluorescence Imaging
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Nanoparticles (NPs) are currently developed for drug delivery and molecular imaging. However, they often get intercepted before reaching their target, leading to low targeting efficacy and signal-to-noise ratio. They tend to accumulate in organs like lungs, liver, kidneys, and spleen. The remedy is to iteratively engineerNP surface properties and administration strategies, presently a time-consuming process that includes dissection at different time points. To improve this, we propose a rapid iterative approach using whole-animal X-ray fluorescence (XRF) imaging to systematically evaluate NP distribution in vivo. We applied this method to molybdenum-based NPs and clodronate liposomes for tumor targeting with transient macrophage depletion, leading to reduced accumulations in lungs and liver and eventual tumor detection.XRF computed tomography (XFCT) provided 3D insight into NP distribution within the tumor. We validated the results using a multiscale imaging approach with dye-doped NPs and gene expression analysis for nanotoxicological profiling. XRF imaging holds potential for advancing therapeutics and diagnostics in preclinical pharmacokinetic studies.
  •  
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