| 1. |
- Shaali, Mehrnaz, 1981, et al.
(author)
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Site-selective immobilization of functionalized DNA origami on nanopatterned Teflon AF
- 2017
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In: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 5:30, s. 7637-7643
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Journal article (peer-reviewed)abstract
- We demonstrate the use of arrays of Teflon AF nanopillars for directing the assembly of single rectangular DNA origami scaffolds, functionalized with covalently linked fluorophore molecules, in defined positions on patterned surfaces. This is achieved by introducing Teflon AF as a non-amplified negative e-beam resist, which is exposed and chemically developed to generate arrays of hydrophobic nanopillars with a minimum feature size 40 nm. Binding of the DNA origami to the pillars is facilitated by porphyrin moieties that act as hydrophobic molecular anchors, reaching 80% coverage of the available sites. This combination of top-down lithography and bottom-up self assembly is an efficient means of fabricating hierarchically structured bio-nanointerfaces in which the positioning of functional units is precisely controlled on the molecular scale inside the DNA assembly, and on the nanoscale at pre-designed locations on the substrate.
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| 2. |
- Gözen, Irep, 1980, et al.
(author)
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Thermal migration of molecular lipid films as a contactless fabrication strategy for lipid nanotube networks
- 2013
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In: Lab on a Chip - Miniaturisation for Chemistry and Biology. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 13:19, s. 3822-3826
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Journal article (peer-reviewed)abstract
- We demonstrate the contactless generation of lipid nanotube networks by means of thermally induced migration of flat giant unilamellar vesicles (FGUVs), covering micro-scale areas on oxidized aluminum surfaces. A temperature gradient with a reach of 20 mm was generated using a focused IR laser, leading to a surface adhesion gradient, along which FGUVs could be relocated. We report on suitable lipid-substrate combinations, highlighting the critical importance of the electrostatic interactions between the engineered substrate and the membrane for reversible migration of intact vesicles.
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| 3. |
- Kim, Anna, 1989, et al.
(author)
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SU-8 free-standing microfluidic probes
- 2017
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In: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 11:1
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Journal article (peer-reviewed)abstract
- We present a process for fabrication of free-standing SU-8 probes, with a dry, mechanical release of the final micro-devices. The process utilizes the thermal release tape, a commonly used cleanroom material, for facile heat-release from the sacrificial layer. For characterization of the SU-8 microfluidic probes, two liquid interfaces were designed: a disposable interface with integrated wells and an interface with external liquid reservoirs. The versatility of the fabrication and the release procedures was illustrated by further developing the process to functionalize the SU-8 probes for impedance sensing, by integrating metal thin-film electrodes. An additional interface scheme which contains electronic components for impedance measurements was developed. We investigated the possibilities of introducing perforations in the SU-8 device by photolithography, for solution sampling predominantly by diffusion. The SU-8 processes described here allow for a convenient batch production of versatile free-standing microfluidic devices with well-defined tip-geometry. (C) 2017 Author(s).
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| 4. |
- Kirejev, Vladimir, 1984, et al.
(author)
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Contactless Stimulation and Control of Biomimetic Nanotubes by Calcium Ion Gradients
- 2018
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In: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 14:21
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Journal article (peer-reviewed)abstract
- Membrane tubular structures are important communication pathways between cells and cellular compartments. Studying these structures in their native environment is challenging, due to the complexity of membranes and varying chemical conditions within and outside of the cells. This work demonstrates that a calcium ion gradient, applied to a synthetic lipid nanotube, triggers lipid flow directed toward the application site, resulting in the formation of a bulge aggregate. This bulge can be translated in a contactless manner by moving a calcium ion source along the lipid nanotube. Furthermore, entrapment of polystyrene nanobeads within the bulge does not tamper the bulge movement and allows transporting of the nanoparticle cargo along the lipid nanotube. In addition to the synthetic lipid nanotubes, the response of cell plasma membrane tethers to local calcium ion stimulation is investigated. The directed membrane transport in these tethers is observed, but with slower kinetics in comparison to the synthetic lipid nanotubes. The findings of this work demonstrate a novel and contactless mode of transport in lipid nanotubes, guided by local exposure to calcium ions. The observed lipid nanotube behavior can advance the current understanding of the cell membrane tubular structures, which are constantly reshaped during dynamic cellular processes.
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| 5. |
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| 6. |
- Shaali, Mehrnaz, 1981
(author)
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Advances in Soft Matter Nanofabrication
- 2015
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Doctoral thesis (other academic/artistic)abstract
- The focus of this thesis is placed on the fabrication of engineered nanodevices for the manipulation of soft matter thin films. By combining top-down micro- and nanofabrication approaches with bottom-up self-assembly strategies, new research platforms were developed, tested and characterized.A large part of the studies described herein were performed on electron beam-sculpted Teflon AF surfaces, which served as substrate for molecular lipid films and biological cells. The effects of e-beam exposure of Teflon AF deposits, including changes in hydrophobicity, topography, surface potential and roughness, have been investigated in detail. Lipophilic nanolanes of 50 nm width were created in this manner. The studies show, for example, how spreading of a phospholipid monolayer film originating from a single giant multilamellar vesicle source can be confined and guided by e-beam-exposed frames on the polymer surface. The studies also reveal the preferential adhesion of biological cells on these e-beam-treated Teflon AF surfaces, where the shape of the patterned areas strongly affects cell adhesion.By applying perfluorinated solvent as developer to complete the ebeam-lithography procedure, Teflon AF was introduced as non-amplified negative e-beam resist. Nanostructures with feature sizes as small as 30 nm in width and 40 nm in pitch were fabricated. This new resist was characterized by determining its contrast, sensitivity, and film thickness. The accommodation of single DNA origami scaffolds on developed Teflon AF nanopillars has been investigated as an exemplary application, and about 80% coverage of the available pillar surface was achieved.Moreover, a novel, contact-free technology was developed to generate surface-supported networks of lipid nanotubes and flat giant unilamellar vesicles on a micro-patterned SU-8 substrate. The nanotubes were formed by thermomigration of a phospholipid double bilayer, where the migration of lipid material on the patterned surface was initiated and controlled by a temperature gradient created with an IR laser. In the work presented here, a number of specific problems have been tackled in an interdisciplinary approach, making use of micro- and nanotechnologies, new materials and biomimetic principles that can open up new experimental opportunities to address further fundamental research questions.
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| 7. |
- Shaali, Mehrnaz, 1981, et al.
(author)
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Nanopatterning of Mobile Lipid Mono layers on Electron-Beam-Sculpted Teflon AF Surfaces
- 2015
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In: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 9:2, s. 1271-1279
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Journal article (peer-reviewed)abstract
- Direct electron-beam lithography is used to fabricate nanostructured Teflon AF surfaces, which are utilized to pattern,surface-supported monolayer phospholipid films with 50 nm lateral feature size. In comparison with unexposed Teflon AF coatings, e-beam-irradiated areas show reduced surface tension and surface potential. For phospholipid monolayer spreading experiments, these areas can be designed to function as barriers that enclose unexposed areas of nanometer dimensions and confine the lipid film within. We show that the effectiveness of the barrier is defined by pattern geometry and radiation dose. This surface preparation technique represents an efficient, yet simple, nanopatterning strategy supporting studies of lipid monolayer behavior in ultraconfined spaces. The generated structures are useful for imaging studies of biomimetic membranes and other specialized surface applications requiring spatially controlled formation of self-assembled, molecularly thin films on optically transparent patterned polymer surfaces with very low autofluorescence.
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