| 41. |
- Jafari Jam, R., et al.
(författare)
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Embedded sacrificial AlAs segments in GaAs nanowires for substrate reuse
- 2020
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Ingår i: Nanotechnology. - Bristol : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 31:20
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Tidskriftsartikel (refereegranskat)abstract
- We report on the use of a sacrificial AlAs segment to enable substrate reuse for nanowire synthesis. A silicon nitride template was deposited on a p-type GaAs substrate. Then a pattern was transferred to the substrate by nanoimprint lithography and reactive ion etching. Thermal evaporation was used to define Au seed particles. Metalorganic vapour phase epitaxy was used to grow AlAs-GaAs NWs in the vapour-liquid-solid growth mode. The yield of synthesised nanowires, compared to the number expected from the patterned template, was more than 80%. After growth, the nanowires were embedded in a polymer and mechanically removed from the parent substrate. The parent substrate was then immersed in an HCl:H2O (1:1) mixture to dissolve the remaining stub of the sacrificial AlAs segment. The pattern fidelity was preserved after peeling off the nanowires and cleaning, and the semiconductor surface was flat and ready for reuse. Au seed particles were then deposited on the substrate by use of pulse electrodeposition, which was selective to the openings in the growth template, and then nanowires were regrown. The yield of regrowth was less optimal compared to the first growth but the pattern was preserved. Our results show a promising approach to reduce the final cost of III-V nanowire based solar cells. © 2020 The Author(s). Published by IOP Publishing Ltd.
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| 42. |
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| 43. |
- Kesarimangalam, Sriram, 1983, et al.
(författare)
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Fluorescence Microscopy of Nanochannel-Confined DNA
- 2024
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Ingår i: Methods in Molecular Biology. - 1940-6029 .- 1064-3745. - 9781071633779 - 9781071633762 ; , s. 175-202
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Stretching of DNA in nanoscale confinement allows for several important studies. The genetic contents of the DNA can be visualized on the single DNA molecule level, and the polymer physics of confined DNA and also DNA/protein and other DNA/DNA-binding molecule interactions can be explored. This chapter describes the basic steps to fabricate the nanostructures, perform the experiments, and analyze the data.
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| 44. |
- Kim, Rebekah, et al.
(författare)
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DNA sample cleanup using deterministic lateral displacement
- 2016
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Ingår i: 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016. - 9780979806490 ; , s. 1527-1528
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Konferensbidrag (refereegranskat)abstract
- Optical mapping relies on the preparation of fluorescent DNA. DNA must be imaged with good signal to noise and therefore the background of unwanted DNA fragments, fluorescent dyes and other reagents need to be removed. We use deterministic lateral displacement to separate 48.5 kbp DNA from < 10 kbp DNA. We also show the removal of 48.5 kbp DNA fragments from a background of fluorescent ATTO647N molecules and the recovery of >50 kbp molecules from a background of shorter digested fragments. In both cases improving signal to noise during imaging.
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| 45. |
- Kumra Ahnlide, Vibha, et al.
(författare)
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Nanoscale binding site localization by molecular distance estimation on native cell surfaces using topological image averaging
- 2022
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Ingår i: eLife. - 2050-084X. ; 11, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Antibody binding to cell surface proteins plays a crucial role in immunity, and the location of an epitope can altogether determine the immunological outcome of a host-target interaction. Techniques available today for epitope identification are costly, time-consuming, and unsuited for high-throughput analysis. Fast and efficient screening of epitope location can be useful for the development of therapeutic monoclonal antibodies and vaccines. Cellular morphology typically varies, and antibodies often bind heterogeneously across a cell surface, making traditional particle-averaging strategies challenging for accurate native antibody localization. In the present work, we have developed a method, SiteLoc, for imaging-based molecular localization on cellular surface proteins. Nanometer-scale resolution is achieved through localization in one dimension, namely, the distance from a bound ligand to a reference surface. This is done by using topological image averaging. Our results show that this method is well suited for antibody binding site measurements on native cell surface morphology and that it can be applied to other molecular distance estimations as well.
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| 46. |
- Lard, Mercy, et al.
(författare)
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Use of dielectrophoresis for directing T cells to microwells before nanostraw transfection : modelling and experiments
- 2022
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 12:47, s. 30295-30303
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Tidskriftsartikel (refereegranskat)abstract
- Nanostraw substrates have great potential for achieving minimally invasive cell transfection. Cells located on the nanostraw substrate are subjected to mild DC electric pulses applied across the nanostraw substrate, which open pores in the cell membrane on top of the nanostraws and drives charged cargo through these pores via electrophoresis. However, with this method, the current may leak through uncovered nanostraws, thereby decreasing the desired effect in the cell-covered nanostraws. A minimization of the number of uncovered nanostraws could be achieved by high cell coverage, but this is challenging when working with small cell populations. Nanostraw substrates of smaller area could be covered by smaller cell populations but are hard to integrate into fluidics systems. Here, we use simulations and experiments to show that this issue can be addressed by covering the nanostraw substrate with an insulating layer containing pores of similar size to cells. The pores act as traps into which cells can be guided using dielectrophoresis, ensuring a high degree of occupancy while maintaining a high cell viability, even if the total number of cells is low.
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| 47. |
- Mafla-Endara, Paola M, et al.
(författare)
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Exposure to polystyrene nanoplastics reduces bacterial and fungal biomass in microfabricated soil models
- 2023
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Ingår i: Science of the Total Environment. - 1879-1026. ; 904
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Tidskriftsartikel (refereegranskat)abstract
- Nanoplastics have been proven to induce toxicity in diverse organisms, yet their effect on soil microbes like bacteria and fungi remains largely unexplored. In this paper, we used micro-engineered soil models to investigate the effect of polystyrene (PS) nanospheres on Pseudomonas putida and Coprinopsis cinerea. Specifically, we explored the effects of increasing concentrations of 60 nm carboxylated bovine serum albumin (BSA) coated nanospheres (0, 0.5, 2, and 10 mg/L) on these bacterial and fungal model organisms respectively, over time. We found that both microorganisms could disperse through the PS solution, but long-distance dispersal was reduced by high concentrations. Microbial biomass decreased in all treatments, in which bacteria showed a linear dose response with the strongest effect at 10 mg/L concentration, and fungi showed a non-linear response with the strongest effect at 2 mg/L concentration. At the highest nanoplastics concentration, the first colonizing fungal hyphae adsorbed most of the PS nanospheres present in their vicinity, in a process that we termed the 'vacuum cleaner effect'. As a result, the toxicity effect of the original treatment on subsequently growing fungal hyphae was reduced to a growth level indistinguishable from the control. We did not find evidence that nanoplastics are able to penetrate bacterial nor fungal cell walls. Overall, our findings provide evidence that nanoplastics can cause a direct negative effect on soil microbes and highlight the need for further studies that can explain how the microbial stress response might affect soil functions.
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| 48. |
- Porro, Gloria, et al.
(författare)
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Deterministic lateral displacement systems with arrayed three-dimensional electrodes for tunable particle sorting
- 2020
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Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 655-656
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Konferensbidrag (refereegranskat)abstract
- Deterministic Lateral Displacement (DLD) is a passive technique employed for particles sorting. We recently introduced a DLD device composed of arrayed three-dimensional metal-covered pillars that can be used to locally apply an electric field. With our system we can exploit the dielectrophoretic (DEP) effect to exert forces on the bioparticles to be sorted, thus dynamically tuning the critical size of the passive sorting device.
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| 49. |
- Samuelsson, Malin, et al.
(författare)
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RhoB controls the Rab11-mediated recycling and surface reappearance of LFA-1 in migrating T lymphocytes
- 2017
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Ingår i: Science Signaling. - Washington, DC, USA : American Association for the Advancement of Science (A A A S). - 1945-0877 .- 1937-9145. ; 10:509
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Tidskriftsartikel (refereegranskat)abstract
- The regulation of cell adhesion and motility is complex and requires the intracellular trafficking of integrins to and from sites of cell adhesion, especially in fast-moving cells such as leukocytes. The Rab family of guanosine triphosphatases (GTPases) is essential for vesicle transport, and vesicles mediate intracellular integrin trafficking. We showed that RhoB regulates the vesicular transport of the integrin LFA-1 along the microtubule network in migrating T lymphocytes. Impairment in RhoB function resulted in the accumulation of both LFA-1 and the recycling endosomal marker Rab11 at the rear of migrating T lymphocytes and decreased the association between these molecules. T lymphocytes lacking functional RhoB exhibited impaired recycling and subsequently decreased surface amounts of LFA-1, leading to reduced T cell adhesion and migration mediated by the cell adhesion molecule ICAM-1 (intercellular adhesion molecule-1). We propose that vesicle-associated RhoB is a regulator of the Rab11-mediated recycling of LFA-1 to the cell surface, an event that is necessary for T lymphocyte motility.
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| 50. |
- Ström, Oskar E., et al.
(författare)
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DNA concentration wave formation in pillar arrays
- 2020
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Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 240-241
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Konferensbidrag (refereegranskat)abstract
- High throughput in particle and molecular sorting schemes is an important performance indicator and can be realized through increased volumetric processing rates or increased concentrations. Here we investigate the effect of increased concentration of high-molecular weight DNA in micropillar arrays for deterministic lateral displacement (DLD). We find that the array imposes regular fluctuations in the concentration of the DNA if the sample concentration and flow rates exceed respective threshold values. We characterize the resulting concentration waves and study their influence on microsphere trajectories in the device. We expect our results to be relevant e.g. for sample preparation of cell lysates which can often be complicated by the release of chromosomal DNA.
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