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| 2. |
- Abrahamsson, Christoffer K., et al.
(författare)
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Magnetically induced structural anisotropy in binary colloidal gels and its effect on diffusion and pressure driven permeability
- 2014
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 10:24, s. 4403-4412
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Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis, microstructure and mass transport properties of a colloidal hydrogel self-assembled from a mixture of colloidal silica and nontronite clay plates at different particle concentrations. The gel-structure had uniaxial long-range anisotropy caused by alignment of the clay particles in a strong external magnetic field. After gelation the colloidal silica covered the clay particle network, fixing the orientation of the clay plates. Comparing gels with a clay concentration between 0 and 0.7 vol%, the magnetically oriented gels had a maximum water permeability and self-diffusion coefficient at 0.3 and 0.7 vol% clay, respectively. Hence the specific clay concentration resulting in the highest liquid flux was pressure dependent. This study gives new insight into the effect of anisotropy, particle concentration and bound water on mass transport properties in nano/microporous materials. Such findings merit consideration when designing porous composite materials for use in for example fuel cell, chromatography and membrane technology.
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| 3. |
- Abrahamsson, Christoffer, 1984, et al.
(författare)
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Magnetically induced structural anisotropy in binary colloidal gels and its effect on diffusion and pressure driven permeability
- 2014
-
Ingår i: Soft Matter. - 1744-683X .- 1744-6848. ; 10:24, s. 4403-4412
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis, microstructure and mass transport properties of a colloidal hydrogel selfassembled from a mixture of colloidal silica and nontronite clay plates at different particle concentrations. The gel-structure had uniaxial long-range anisotropy caused by alignment of the clay particles in a strong external magnetic field. After gelation the colloidal silica covered the clay particle network, fixing the orientation of the clay plates. Comparing gels with a clay concentration between 0 and 0.7 vol%, the magnetically oriented gels had a maximum water permeability and self-diffusion coefficient at 0.3 and 0.7 vol% clay, respectively. Hence the specific clay concentration resulting in the highest liquid flux was pressure dependent. This study gives new insight into the effect of anisotropy, particle concentration and bound water on mass transport properties in nano/microporous materials. Such findings merit consideration when designing porous composite materials for use in for example fuel cell, chromatography and membrane technology.
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| 4. |
- Abrikossov, Alexei, et al.
(författare)
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Self-assembly of spherical colloidal particles with off-centered magnetic dipoles
- 2013
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 9:37, s. 8904-8913
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Tidskriftsartikel (refereegranskat)abstract
- Fluids of spherical colloids possessing an off-centered embedded magnetic dipole were investigated by using Monte Carlo simulations. Systems of colloids with different strengths and directions of the embedded dipole moment confined in a 2D space without and with an external magnetic field applied were considered. The fluids were characterized by radial distribution functions, angular distribution functions, cluster data, and energetic data. In the absence of an external field, the colloids form dimers and trimers at sufficiently large magnetic moment without the tendency of forming chains of colloids as appearing in systems with particles possessing a central magnetic dipole. In the presence of an external field, chains of colloids aligned in a zigzag fashion were formed for a field parallel to the plane of the particles, whereas the colloidal ordering was suppressed in the presence of a field perpendicular to that plane. The findings agree surprisingly well with the recent experimental observations on fluids containing spherical polymer colloids with embedded single-domain magnetic hematite cubes (S. Sacanna, L. Rossi, and D. J. Pine, J. Am. Chem. Soc., 2012, 134, 6112).
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| 5. |
- Abrikossov, Alexei, et al.
(författare)
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Steering patchy particles using multivalent electrolytes
- 2017
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 13:26, s. 4591-4597
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Tidskriftsartikel (refereegranskat)abstract
- Proteins and many recently designed colloids can be regarded as patchy particles where directional interactions strongly influence and govern assembly behavior. Using explicit ion implicit solvent Metropolis Monte Carlo simulations, we investigate spherical model particles, carrying both charge and electric patches, in dilute aqueous 1 : 1, 1 : 3, and 3 : 1 electrolyte solutions. Striking differences in pair interaction free energies and orientational correlations are induced by three different salts which are discussed and rationalized in terms of ion-binding to surface groups, ion-ion correlations, and double layer forces. These findings suggest a general strategy where directional, intermolecular interactions can be invoked and tuned via small amounts of a carefully chosen electrolyte.
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| 6. |
- Acciaro, Roberta, et al.
(författare)
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Investigation of the formation, structure and release characteristics of self-assembled composite films of cellulose nanofibrils and temperature responsive microgels
- 2011
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 7:4, s. 1369-1377
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of forming self-organized films using charge-stabilized dispersions of cellulose I nanofibrils and microgel beads of poly-(N-isopropylacrylamide-co-acrylic acid) copolymer is presented. The build-up behavior and the properties of the layer-by-layer (LbL)-constructed films were studied using quartz crystal microbalance with dissipation (QCM-D) and ellipsometry. The morphology of the formed films was also characterized using atomic force microscopy (AFM) imaging. The applied methods clearly demonstrated the successful LbL-assembly of the monodisperse microgels and nanofibrils. The in situ QCM-D measurements also revealed that contrary to the polyelectrolyte bound microgel particles, the nanofibrils-bound gel beads preserve their highly swollen state and do not suffer a partial collapse due to the lack of interdigitation of the oppositely charged components. To probe the accessibility of the gel beads in the formed films, the room temperature (similar to 25 degrees C) loading and release of a fluorescent dye (FITC) was also investigated. The incorporation of the cellulose nanofibrils into the multilayer resulted in an open structure that was found easily penetrable for the dye molecules even at constant room temperature, which is in sharp contrast with previously reported systems based on synthetic polyelectrolytes. The amount of dye released from the multilayer films could be fine-tuned with the number of bilayers. Finally, the thermoresponsivity of the films was also shown by triggering the burst release of the loaded dye when the film was collapsed.
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| 7. |
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| 8. |
- Ainalem, Marie-Louise, et al.
(författare)
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DNA condensation using cationic dendrimers-morphology and supramolecular structure of formed aggregates
- 2011
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 7:10, s. 4577-4594
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Forskningsöversikt (refereegranskat)abstract
- The control of DNA condensation, i.e. packaging or compaction, is essential for the living cell, but also important in many applications. One example is gene therapy that often utilises vehicles with the ability to condense DNA and thereby protect DNA against degradation, transport DNA across membranes (which act as barriers towards gene delivery), and regulate gene expression. This review discusses the ability of poly(amido amine) dendrimers to condense DNA molecules via attractive electrostatic interactions, which in turn leads to self-assembled structures with a rich variety of morphologies. The process of condensation is cooperative and kinetically controlled, and the structure of the aggregates strongly depends on the size and charge of the dendrimer, and the salt concentration of the aqueous solution. While globular aggregates are formed by large dendrimers, rods and toroids are formed by smaller sized dendrimers with lower total charge per molecule. The globular aggregates appear to be disordered, but the smaller dendrimers give rise to high-ordered packing of the DNA in ordered arrays according to a square or hexagonal unit cell. The high-ordered packing also indicates that the dendrimers deform while inducing the DNA to condense.
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| 9. |
- Akesson, Anna, et al.
(författare)
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Composition and structure of mixed phospholipid supported bilayers formed by POPC and DPPC
- 2012
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 8:20, s. 5658-5665
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a systematic study of the morphology and composition of supported lipid bilayers (SLBs) formed by vesicle fusion using a wide variety of surface sensitive techniques that give information about the lateral as well as vertical structure and bilayer fluidity. SLBs of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) mixtures at five different bulk vesicle compositions were formed in such a way that the phase separation boundaries were crossed. For all compositions studied, the SLBs were systematically enriched with POPC compared to the nominal vesicle composition. Nevertheless, gel-fluid domain coexistence was observed for SLB compositions in which phase separation was expected based on the bulk phase diagram. The probable causes for the compositional difference in the SLBs are discussed in terms of the phase behaviour of the mixture and its effect on the membrane formation process by vesicle fusion.
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| 10. |
- Albet-Torres, Nuria, et al.
(författare)
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Molecular motors on lipid bilayers and silicon dioxide: different driving forces for adsorption
- 2010
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 6:14, s. 3211-3219
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how different types of interactions govern adsorption of the myosin motor fragment heavy meromyosin (HMM) onto different substrates is important in functional studies of actomyosin and for the development of motor powered lab-on-a-chip applications. In this study, we have combined in vitro motility assays and quartz crystal microbalance with dissipation (QCM-D) monitoring to investigate the underlying adsorption mechanisms of HMM onto supported lipid bilayers in comparison with pure and silanized SiO2. The QCM-D results, combined with data showing actin transportation by HMM adsorbed onto positively charged supported lipid bilayers, suggest reversible HMM surface adsorption via the negatively charged coiled-coil tail region. In contrast, the QCM-D data for HMM adsorption onto negatively charged lipids support a model according to which HMM adsorbs onto negatively charged surfaces largely via the positively charged actin binding regions. Adsorption studies at low (30-65 mM) and high (185-245 mM) ionic strengths onto piranha cleaned SiO2 surfaces (contact angle
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