| 1. |
- Fernandez, Yuri A. Diaz, 1978, et al.
(författare)
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The conquest of middle-earth: combining top-down and bottom-up nanofabrication for constructing nanoparticle based devices
- 2014
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 6:24, s. 14605-14616
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Tidskriftsartikel (refereegranskat)abstract
- The development of top-down nanofabrication techniques has opened many possibilities for the design and realization of complex devices based on single molecule phenomena such as e. g. single molecule electronic devices. These impressive achievements have been complemented by the fundamental understanding of self-assembly phenomena, leading to bottom-up strategies to obtain hybrid nanomaterials that can be used as building blocks for more complex structures. In this feature article we highlight some relevant published work as well as present new experimental results, illustrating the versatility of self-assembly methods combined with top-down fabrication techniques for solving relevant challenges in modern nanotechnology. We present recent developments on the use of hierarchical self-assembly methods to bridge the gap between sub-nanometer and micrometer length scales. By the use of non-covalent self-assembly methods, we show that we are able to control the positioning of nanoparticles on surfaces, and to address the deterministic assembly of nano-devices with potential applications in plasmonic sensing and single-molecule electronics experiments.
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| 2. |
- Gschneidtner, Tina, 1985, et al.
(författare)
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A Versatile Self-Assembly Strategy for the Synthesis of Shape-Selected Colloidal Noble Metal Nanoparticle Heterodimers
- 2014
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 30:11, s. 3041-3050
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Tidskriftsartikel (refereegranskat)abstract
- The self-assembly of individual nanoparticles into-dimers so-called heterodimers-is relevant for a broad range of applications, in particular in the vibrant field of nano-plasmonics and nanooptics. In this paper we report the synthesis and characterization of material- and shape-selected nanoparticle heterodimers assembled from individual particles via electrostatic interaction. The versatility of the synthetic strategy is shown by assembling combinations of metal particles of different shapes, sizes, and metal compositions like a gold sphere (90 nm) with either a gold cube (35 nm), gold rhombic dodecahedron (50 nm), palladium truncated cube (120 nm), palladium rhombic dodecahedron (110 nm), palladium octahedron (130 nm), or palladium cubes (25 and 70 nm) as well as a silver sphere (90 nm) with palladium cubes (25 and 70 nm). The obtained heterodimer combinations are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), scanning transmission electron microscopy energy dispersive X-ray spectroscopy (STEM-EDX), dynamic light scattering (DLS), and zeta-potential measurements. We describe the optimal experimental conditions to achieve the highest yield of heterodimers compared to other aggregates. The experimental results have been rationalized using theoretical modeling. A proof-of-principle experiment where individual Au-Pd heterodimers are exploited for indirect plasmonic sensing of hydrogen finally illustrates the potential of these structures to probe catalytic processes at the single particle level.
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| 3. |
- Levin, Sune, 1991, et al.
(författare)
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Nanofluidic Trapping of Faceted Colloidal Nanocrystals for Parallel Single-Particle Catalysis
- 2022
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Ingår i: Acs Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:9
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Tidskriftsartikel (refereegranskat)abstract
- Catalyst activity can depend distinctly on nano -particle size and shape. Therefore, understanding the structure sensitivity of catalytic reactions is of fundamental and technical importance. Experiments with single-particle resolution, where ensemble-averaging is eliminated, are required to study it. Here, we implement the selective trapping of individual spherical, cubic, and octahedral colloidal Au nanocrystals in 100 parallel nanofluidic channels to determine their activity for fluorescein reduction by sodium borohydride using fluorescence microscopy. As the main result, we identify distinct structure sensitivity of the rate-limiting borohydride oxidation step originating from different edge site abundance on the three particle types, as confirmed by first -principles calculations. This advertises nanofluidic reactors for the study of structure-function correlations in catalysis and identifies nanoparticle shape as a key factor in borohydride-mediated catalytic reactions.
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| 4. |
- Lubart, Quentin, 1989, et al.
(författare)
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High throughput size-determination and multiplexed fluorescence analysis of single biological particles in a nanofluidic device
- 2019
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Ingår i: 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019. ; , s. 1420-1421
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Konferensbidrag (refereegranskat)abstract
- Biological nanoparticles, such as exosomes and viruses, are responsible for a multitude of important functions, but methods to characterize them on the single particle level are rare. We here present a nanofluidic platform for multi-parametric characterization of biological nanoparticles with high throughput. The device consists of feeding microchannels and an array of ~100 nanochannels where the nanoparticles can be characterized. We determine the size by analyzing the Brownian motion of the particles and quantify their content based on fluorescence imaging of up to three different colors. We successfully benchmark our method against existing techniques, such as Nanoparticle Tracking Analysis (NTA).
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| 5. |
- Syrenova, Svetlana, 1987, et al.
(författare)
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Hydride formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape
- 2015
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Ingår i: Nature Materials. - 1476-4660 .- 1476-1122. ; 14:12, s. 1236-1244
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Tidskriftsartikel (refereegranskat)abstract
- Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of hydride formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during hydride formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that hydride decomposition either occurs incoherently or via different kinetic pathways.
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| 6. |
- Friedrich, R., et al.
(författare)
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A nano flow cytometer for single lipid vesicle analysis
- 2017
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Ingår i: Lab on a Chip - Miniaturisation for Chemistry and Biology. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 17:5, s. 830-841
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Tidskriftsartikel (refereegranskat)abstract
- We present a nanofluidic device for fluorescence-based detection and characterization of small lipid vesicles on a single particle basis. The device works like a nano flow cytometer where individual vesicles are visualized by fluorescence microscopy while passing through parallel nanochannels in a pressure-driven flow. An experiment requires less than 20 mu l sample volume to quantify both the vesicle content and the fluorescence signals emitted by individual vesicles. We show that the device can be used to accurately count the number of fluorescent synthetic lipid vesicles down to a vesicle concentration of 170 fM. We also show that the size-distribution of the vesicles can be resolved from their fluorescence intensity distribution after calibration. We demonstrate the applicability of the assay in two different examples. In the first, we use the nanofluidic device to determine the particle concentration in a sample containing cell-derived extracellular vesicles labelled with a lipophilic dye. In the second, we demonstrate that dual-color detection can be used to probe peptide binding to synthetic lipid vesicles; we identify a positive membrane-curvature sensing behavior of an arginine enriched version of the Antennapedia homeodomain peptide penetratin. Altogether, these results illustrate the potential of this nanofluidic-based methodology for characterization and quantification of small biological vesicles and their interactors without ensemble averaging. The device is therefore likely to find use as a quantitative analytical tool in a variety of fields ranging from diagnostics to fundamental biology research. Moreover, our results have potential to facilitate further development of automated lab-on-a-chip devices for vesicle analysis.
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| 7. |
- Levin, Sune, 1991, et al.
(författare)
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A nanofluidic device for parallel single nanoparticle catalysis in solution
- 2019
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Studying single catalyst nanoparticles, during reaction, eliminates averaging effects that are an inherent limitation of ensemble experiments. It enables establishing structure-function correlations beyond averaged properties by including particle-specific descriptors such as defects, chemical heterogeneity and microstructure. Driven by these prospects, several single particle catalysis concepts have been implemented. However, they all have limitations such as low throughput, or that they require very low reactant concentrations and/or reaction rates. In response, we present a nanofluidic device for highly parallelized single nanoparticle catalysis in solution, based on fluorescence microscopy. Our device enables parallel scrutiny of tens of single nanoparticles, each isolated inside its own nanofluidic channel, and at tunable reaction conditions, ranging from the fully mass transport limited regime to the surface reaction limited regime. In a wider perspective, our concept provides a versatile platform for highly parallelized single particle catalysis in solution and constitutes a promising application area for nanofluidics.
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| 8. |
- Singh, Vandana, 1985, et al.
(författare)
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Quantification of single-strand DNA lesions caused by the topoisomerase II poison etoposide using single DNA molecule imaging
- 2022
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Ingår i: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 594, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- DNA-damaging agents, such as radiation and chemotherapy, are common in cancer treatment, but the dosing has proven to be challenging, leading to severe side effects in some patients. Hence, to be able to personalize DNA-damaging chemotherapy, it is important to develop fast and reliable methods to measure the resulting DNA damage in patient cells. Here, we demonstrate how single DNA molecule imaging using fluorescence microscopy can quantify DNA-damage caused by the topoisomerase II (TopoII) poison etoposide. The assay uses an enzyme cocktail consisting of base excision repair (BER) enzymes to repair the DNA damage caused by etoposide and label the sites using a DNA polymerase and fluorescently labeled nucleotides. Using this DNA-damage detection assay we find a large variation in etoposide induced DNA-damage after in vitro treatment of blood cells from healthy individuals. We furthermore used the TopoII inhibitor ICRF-193 to show that the etoposide-induced damage in DNA was TopoII dependent. We discuss how our results support a potential future use of the assay for personalized dosing of chemotherapy.
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| 9. |
- Singh, Vandana, 1985, et al.
(författare)
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Quantifying DNA damage induced by ionizing radiation and hyperthermia using single DNA molecule imaging
- 2020
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Ingår i: Translational Oncology. - : Elsevier BV. - 1936-5233. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- Ionizing radiation (IR) is a common mode of cancer therapy, where DNA damage is the major reason of cell death. Here, we use an assay based on fluorescence imaging of single damaged DNA molecules isolated from radiated lymphocytes, to quantify IR induced DNA damage. The assay uses a cocktail of DNA-repair enzymes that recognizes and excises DNA lesions and then a polymerase and a ligase incorporate fluorescent nucleotides at the damage sites, resulting in a fluorescent “spot” at each site. The individual fluorescent spots can then be counted along single stretched DNA molecules and the global level of DNA damage can be quantified. Our results demonstrate that inclusion of the human apurinic/apyrimidinic endonuclease 1 (APE1) in the enzyme cocktail increases the sensitivity of the assay for detection of IR induced damage significantly. This optimized assay also allowed detection of a cooperative increase in DNA damage when IR was combined with mild hyperthermia, which is sometimes used as an adjuvant in IR therapy. Finally, we discuss how the method may be used to identify patients that are sensitive to IR and other types of DNA damaging agents. © 2020 The Authors
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| 10. |
- Singh, Vandana, 1985, et al.
(författare)
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Shining light on single-strand lesions caused by the chemotherapy drug bleomycin
- 2021
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Ingår i: DNA Repair. - : Elsevier BV. - 1568-7864 .- 1568-7856. ; 105
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Tidskriftsartikel (refereegranskat)abstract
- Quantification of the DNA damage induced by chemotherapy in patient cells may aid in personalization of the dose used. However, assays to evaluate individual patient response to chemotherapy are not available today. Here, we present an assay that quantifies single-stranded lesions caused by the chemotherapeutic drug Bleomycin (BLM) in peripheral blood mononuclear cells (PBMCs) isolated from healthy individuals. We use base excision repair (BER) enzymes to process the DNA damage induced by BLM and then extend the processed sites with fluorescent nucleotides using a DNA polymerase. The fluorescent patches are quantified on single DNA molecules using fluorescence microscopy. Using the assay, we observe a significant variation in the in vitro induced BLM damage and its repair for different individuals. Treatment of the cells with the BER inhibitor CRT0044876 leads to a lower level of repair of BLM-induced damage, indicating the ability of the assay to detect a compromised DNA repair in patients. Overall, the data suggest that our assay could be used to sensitively detect the variation in BLM-induced DNA damage and repair in patients and can potentially be able to aid in personalizing patient doses.
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