| 1. |
- Sköld, Niklas, et al.
(författare)
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Nanofluidics in hollow nanowires
- 2010
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Ingår i: NANOTECHNOLOGY. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 21:15
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel scheme for producing nanotube membranes using free-standing hollow nanowires, with easily controllable dimensions. GaAs–AlInP core–shell nanowires were grown by metal–organic vapor phase epitaxy and were partially embedded in a polymer film. The GaAs core and substrate were etched selectively, leaving tubes with open access to both sides of the membrane. Electrophoretic transport of T4-phage DNA through the hollow nanowires was demonstrated using epifluorescence microscopy.
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| 2. |
- Beck, Marc, et al.
(författare)
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Fabrication and characterization of a molecular adhesive layer for micro- and nanofabricated electrochemical electrodes
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- When making nanoelectrodes for applications in liquid cells it is plausible that the less noble metal layer may be negatively affected, i.e. it will be etched away leading to very unstable conditions during operation. Here we describe a dry method to produce such a molecular layer consisting of mercaptopropyltriethoxysilane (MPTS) making it possible to controllable and reproducibly form a covalently bound monolayer of MPTS to the SiO2 surface. From Photoelectron Spectroscopy measurements we could conclude that the layer thickness corresponds to a monolayer. We have electrochemically characterized such electrodes by cyclic voltammetry. Furthermore, we have successfully patterned such layers at both micro- and nanometer scale showing the possibilities to fabricate chemically selective and active areas that may be used in various applications
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| 3. |
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| 4. |
- Ling, TGI, et al.
(författare)
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Fa-brication and characterization of a molecular adhesive layer for micro- and nanofabricated electrochemical electrodes
- 2003
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Ingår i: Microelectronic Engineering. - 1873-5568. ; 67-8, s. 887-892
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Tidskriftsartikel (refereegranskat)abstract
- In the microelectronics industry, gold electrodes on silicon dioxide are produced using an adhesive layer of chromium or titanium. This method is applicable whenever a dry environment is present. However, when such an electrode is exposed to an electrolyte a galvanic cell is formed and the less noble metal will dissolve and eventually destroy the electrode. We describe here how a monolayer of mercaptopropyl-trimethoxysilane (MPTS) can be used as an adhesive. The layer can be structured lithographically making gold electrodes in the micro- and nano-range applicable for use in electrochemistry. The properties of the MPTS layer were investigated with photoelectron microscopy, atomic force microscopy and the electrochemical performance of the gold electrodes was determined by cyclic voltammetry. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 5. |
- Mansson, A, et al.
(författare)
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Actin-based molecular motors for cargo transportation in nanotechnology - Potentials and challenges
- 2005
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Ingår i: IEEE Transactions on Advanced Packaging. - 1521-3323. ; 28:4, s. 547-555
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Tidskriftsartikel (refereegranskat)abstract
- Here, we review the use of actin-based motors, (myosins; e.g., the molecular motor of muscle) in. nanotechnology. The review starts from the viewpoints of the molecular motors as being important devices responsible of cargo transportation in the cell and end in discussions about their employment in nanotechnological applications. First, we describe basic biophysics of the myosin motors with focus on their involvement in cargo transportation in the living cell, leading us over into a discussion about in vitro motility assays. These are biological test systems where the myosin-induced translocation of actin filaments is studied on an artificial surface outside the cell. Then follows a review about modified motility assays for production of ordered motion. Here, we discuss ours and others' work with regards to making micro- and nanostructured surfaces and channels where the position and direction of movement produced by molecular motors is controlled. In this section, we consider the role of the channel size in promoting unidirectional myosin-induced motion of actin filaments. Furthermore, we consider the usefulness of surface modifications, e.g., various silanization procedures in order to promote and hinder molecular motility, respectively. Particularly, we describe our latest test system being both morphologically and chemically nanostructured giving us unsurpassed possibilities to perform functional studies as well as extremely good spatio-temporal control. Then follows a section about nanotechnological cargo transportation systems based on the actomyosin motor system. For instance, we present results of attaching fluorescent quantum dots as cargoes to the actin filaments. In this section, we also discuss the possibilities of having cargo attachment and detachment being performed on demand. Finally, we consider the usefulness of molecular motors for lab-on-a-chip applications and the requirements for incorporating these motors in commercially viable devices. In this context, the significant potential of the actomyosin motor system to overcome traditional limitations of micro- and nanofluidics is stressed.
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| 6. |
- Montelius, Lars, et al.
(författare)
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Fabrication and characterization of a nanosensor for admittance spectroscopy of biomolecules
- 1995
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Ingår i: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 13:3, s. 1755-1760
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Tidskriftsartikel (refereegranskat)abstract
- We have fabricated nanometer-sized interdigitated electrode patterns using electron beam lithography and liftoff techniques. The aim of the investigation was to find out whether the dimensions (i.e., the electrode separations) of the pattern would affect the admittance signal of the biomolecules in between the electrodes. Since the admittance signal scales with the geometrical factor A/d, where A is the electrode area and d is the separation, we chose to keep A/d constant when changing the electrode separation in order to eliminate this trivial effect on the admittance signal. An interdigitated electrode structure having an interelectrode spacing in the nanometer regime makes it possible to reach high nonstationary as well as stationary electric field strengths while having a low applied voltage level. Hence, electrode reactions will be as small as possible, while a high signal to noise ratio is obtained. We have been able to experimentally study the response of the impedance behavior to high electric fields exhibiting either a positive or a negative shift of the permittivity as a function of the field being a high alternating-current or a direct-current field, respectively.
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| 7. |
- Stollenwerk, Maria, et al.
(författare)
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Quantitation of bacterial adhesion to polymer surfaces by bioluminescence
- 1998
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Ingår i: Zentralblatt fur Bakteriologie. - 0934-8840. ; 287:1-2, s. 7-18
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Tidskriftsartikel (refereegranskat)abstract
- Quantitation of microbes adhering to a surface is commonly used in studies of microbial adhesion to different surfaces. We have quantified different staphylococcal strains adhering to polymer surfaces by measuring bacterial ATP (adenosine triphosphate) by bioluminescence. The method is sensitive, having a detection limit of 104 bacterial cells. Viable counting of bacterial cells may yield falsely low results due to the presence of 'dormant' and adherent bacteria. By using bioluminescence, this can be avoided. Cells of different bacterial species and cells of strains of the same species were shown to differ significantly in their basal ATP content (8.7 x 10-13 - 5.2 x 10-22 MATP). The size of adherent and planktonic bacteria decreased with time (0.7 μm → 0.3 μm, 20 days). During incubation in nutrient-poor buffer ('starvation'), the ATP content of adherent bacteria decreased after 24-96 h whereas that of planktonic bacteria was stable over 20 days. The presence of human serum or plasma did not interfere significantly with the test results. Since the ATP concentration of bacterial strains of different species varies and is also influenced by the growth conditions of bacteria (solid or liquid culture medium), a species-specific standard curve has to be established for bacteria grown under the same culture conditions. We conclude that the method is a sensitive tool to quantify adherent bacteria during experiments lasting for less than 6 h and constitutes a valuable method to be used in conjunction with different microscopical techniques.
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| 8. |
- Tegenfeldt, Jonas, et al.
(författare)
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A Nanosensor for Admittance Spectroscopy
- 1995
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Ingår i: Ultimate Limits of Fabrication and Measurements. - 9789401100410 ; , s. 115-122
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Bokkapitel (refereegranskat)
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| 9. |
- Tegenfeldt, Jonas O., et al.
(författare)
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Image widening not only a question of tip sample convolution
- 1995
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Ingår i: Applied Physics Letters. - 0003-6951.
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Tidskriftsartikel (refereegranskat)abstract
- As the tip in the atomic force microscope is scanned over the sample surface an image results which contains information from the sample as well as from the tip. This mainly results in an increase of the apparent size of the sample. If the tip is reasonably sharp the contribution from the tip is small. In some cases the widening still persists in spite of a very sharp tip. In this letter, a model is presented which ascribes this to the lateral forces twisting the cantilever giving an offset between the apparent point of contact and the real point of contact. This results in a shift between forward and reverse scan of the sample position in the imaging window and, if the lateral forces due to the sample and substrate are different, a change in the apparent width of the sample.
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