| 1. |
- Baks, Tim, et al.
(författare)
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Schrödinger's capsule : a (micro) capsulate that is open and closed, almost, at the same time
- 2010
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Ingår i: Proceedings of the Physics with Industry 2010, 11-15 October 2010, Leiden, The Netherlands. - : Lorentz Center Leiden.
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Konferensbidrag (refereegranskat)abstract
- We exploit different routes for encapsulation of food additives, such as minerals or vitamins, in a polymeric capsule. The added active ingredients should remain inside the capsule for at least a year in an aqueous environment (e.g. a dairy product), since sensory properties or functionality of the ingredients may otherwise be affected. However, after intake the active compound should readily (within 1 h) be released due to the acidic environment in the stomach. First, we propose a phenomenological model in order to study how a polymeric matrix may limit the diffusion of incorporated active molecules. The relation between the release rate of the active compound and its molecular weight is elucidated. Second, the desired capsules may be obtained by specific binding between subunits within the capsule and the active ingredient. We show two examples that rely on this mechanism: amylose-lipid complexes and mixed metal hydroxides. Amylose is able to form inclusion complexes with various types of ligands, including iodine, monoglycerides, fatty acids and alcohols, where the hydrophobic parts of the ligands are entrapped in the hydrophobic helical cavity of amylose. Mixed metal hydroxides are a versatile class of inorganic solids that consist of sheets of metal cations that are octahedrally surrounded by hydroxide molecules. In between these layers anionic species compensate for charge neutrality. In this way, various metal cations (minerals) may be incorporated with a high loading, and negatively charged actives may be placed between the layers. Upon digestion the particles dissolve and the ingredients are digested. Finally, we show that nature has already developed many intriguing capsules.
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| 2. |
- Salieb-Beugelaar, Georgette, et al.
(författare)
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DNA movement in sub-20 nm nanoslits
- 2007
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Ingår i: Proceedings of the 11th International Conference on Miniaturized Systems for Chemistry and Life Sciences, uTAS 2007. - 9780979806407 ; , s. 1201-1203
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Konferensbidrag (refereegranskat)abstract
- The movement of XbaI digested O-DNA in 20 nanometer and O-DNA in 12 nanometer high slits was investigated. We found that DNA moved intermittently and following preferential pathways, indicating an important influence of surface roughness. From these intermittent movements two different mobilities were calculated, the total averaged mobilities and averaged mobilities between the intermittent sticking events. The friction coefficient per unit length was calculated from the latter mobilities. A three order of magnitude increase was found for the 12 nm slits compared to the theoretical value. The mobility furthermore differs less than one order of magnitude between 20 nm and 12 nm slits, and the influence of varying the ionic strength of the buffer was not significant. This work is the first time DNA movement in such shallow constrictions is investigated.
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| 3. |
- Salieb-Beugelaar, Georgette, et al.
(författare)
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Field-Dependent DNA Mobility in 20 nm High Nanoslits.
- 2008
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 8:7, s. 1785-1790
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Tidskriftsartikel (refereegranskat)abstract
- The transport behavior of lambda-DNA (48 kbp) in fused silica nanoslits is investigated upon application of electrical fields of different strengths. The slit dimensions are 20 nm in height, 3 microm in width, and 500 microm in length. With fields of 30 kV/m or below, the molecules move fluently through the slits, while at higher electrical fields, the DNA molecules move intermittently, resulting in a strongly reduced mobility. We propose that the behavior can be explained by mechanical and/or field-induced dielectrophoretic DNA trapping due to the surface roughness in the nanoslits. The observation of preferential pathways and trapping sites of the lambda-DNA molecules through the nanoslits supports this hypothesis and indicates that the classical viscous friction models to explain the DNA movement in nanoslits needs to be modified to include these effects. Preliminary experiments with the smaller XbaI-digested litmus-DNA (2.8 kbp) show that the behavior is size-dependent, suggesting that the high field electrophoresis in nanoslits can be used for DNA separation.
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