| 1. |
- Grzhibovskis, Richards, 1978, et al.
(author)
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Shape of red blood cells in contact with artificial surfaces
- 2017
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In: European Biophysics Journal. - : Springer Science and Business Media LLC. - 1432-1017 .- 0175-7571. ; 46:2, s. 141-148
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Journal article (peer-reviewed)abstract
- The phenomenon of physical contact between red blood cells and artificial surfaces is considered. A fully three-dimensional mathematical model of a bilayer membrane in contact with an artificial surface is presented. Numerical results for the different geometries and adhesion intensities are found to be in agreement with experimentally observed geometries obtained by means of digital holographic microscopy.
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| 2. |
- Voinova, Marina, 1958, et al.
(author)
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Physical processes in polymeric filters used for dialysis
- 2019
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In: Polymers. - : MDPI AG. - 2073-4360. ; 11:3
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Research review (peer-reviewed)abstract
- The key physical processes in polymeric filters used for the blood purification include transport across the capillary wall and the interaction of blood cells with the polymer membrane surface. Theoretical modeling of membrane transport is an important tool which provides researchers with a quantification of the complex phenomena involved in dialysis. In the paper, we present a dense review of the most successful theoretical approaches to the description of transport across the polymeric membrane wall as well as the cell-polymer surface interaction, and refer to the corresponding experimental methods while studying these phenomena in dialyzing filters.
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| 3. |
- Adams, Kelly L., et al.
(author)
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Steady-State Electrochemical Determination of Lipidic Nanotube Diameter Utilizing an Artificial Cell Model
- 2010
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 82:3, s. 1020-1026
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Journal article (peer-reviewed)abstract
- By exploiting the capabilities of steady-state electrochemical measurements, we have measured the inner diameter of a lipid nanotube using Fick’s first law of diffusion in conjunction with an imposed linear concentration gradient of electroactive molecules over the length of the nanotube. Fick’s law has been used in this way to provide a direct relationship between the nanotube diameter and the measurable experimental parameters Δi (change in current) and nanotube length. Catechol was used to determine the Δi attributed to its flux out of the nanotube. Comparing the nanotube diameter as a function of nanotube length revealed that membrane elastic energy was playing an important role in determining the size of the nanotube and was different when the tube was connected to either end of two vesicles or to a vesicle on one end and a pipet tip on the other. We assume that repulsive interaction between neck regions can be used to explain the trends observed. This theoretical approach based on elastic energy considerations provides a qualitative description consistent with experimental data.
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| 4. |
- Carlsson, Nils, 1978, et al.
(author)
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Bicontinuous cubic phase of monoolein and water as medium for electrophoresis of both membrane-bound probes and DNA
- 2006
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In: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 22:9, s. 4408-4414
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Journal article (peer-reviewed)abstract
- Porous hydrogels such as agarose are commonly used to analyze DNA and water-soluble proteins by electrophoresis. However, the hydrophilic environment of these gels is not suitable for separation of important amphiphilic molecules such as native membrane proteins. We show that an amphiphilic liquid crystal of the lipid monoolein and water can be used as a medium for electrophoresis of amphiphilic molecules. In fact, both membrane-bound fluorescent probes and water-soluble oligonucleotides can migrate through the same bicontinuous cubic crystal because both the lipid membrane and the aqueous phase are continuous. Both types of analytes exhibit a field-independent electrophoretic mobility, which suggests that the lipid crystal structure is not perturbed by their migration. Diffusion studies with four membrane probes indicate that membrane-bound analytes experience a friction in the cubic phase that increases with increasing size of the hydrophilic headgroup, while the size of the membrane-anchoring part has comparatively small effect on the retardation.
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| 5. |
- Karlsson, Roger, 1975, et al.
(author)
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Mechanics of lipid bilayer junctions affecting the size of a connecting lipid nanotube
- 2011
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In: Nanoscale Research Letters. - : Springer Science and Business Media LLC. - 1931-7573 .- 1556-276X. ; 6
-
Journal article (peer-reviewed)abstract
- In this study we report a physical analysis of the membrane mechanics affecting the size of the highly curved region of a lipid nanotube (LNT) that is either connected between a lipid bilayer vesicle and the tip of a glass microinjection pipette (tube-only) or between a lipid bilayer vesicle and a vesicle that is attached to the tip of a glass microinjection pipette (two-vesicle). For the tube-only configuration (TOC), a micropipette is used to pull a LNT into the interior of a surface-immobilized vesicle, where the length of the tube L is determined by the distance of the micropipette to the vesicle wall. For the two-vesicle configuration (TVC), a small vesicle is inflated at the tip of the micropipette tip and the length of the tube L is in this case determined by the distance between the two interconnected vesicles. An electrochemical method monitoring diffusion of electroactive molecules through the nanotube has been used to determine the radius of the nanotube R as a function of nanotube length L for the two configurations. The data show that the LNT connected in the TVC constricts to a smaller radius in comparison to the tube-only mode and that tube radius shrinks at shorter tube lengths. To explain these electrochemical data, we developed a theoretical model taking into account the free energy of the membrane regions of the vesicles, the LNT and the high curvature junctions. In particular, this model allows us to estimate the surface tension coefficients from R(L) measurements.
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| 6. |
- Sanandaji, Nima, 1981, et al.
(author)
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Comparison of oligonucleotide mirgation in a bicontinuous cubic phase of monoolein and water and in a fibrous agarose hydrogel
- 2006
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In: Electrophoresis. - : Wiley. - 1522-2683 .- 0173-0835. ; 27:15, s. 3007-3017
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Journal article (peer-reviewed)abstract
- Porous hydrogels such as agarose are commonly used to analyze DNA and water-soluble proteins by electrophoresis. More recently lyotropic liquid crystals, such as the diamond cubic phase formed by the lipid monoolein and water, has become a new type of well-defined porous structure of interest for both hydrophilic and amphiphilic analytes. Here we compare these two types of matrixes by investigating the nature of retardation they confer to an oligonucleotide that migrates in their respective aqueous phases. The retardation for a 25-mer oligonucleotide was found to be about 35-fold stronger in the cubic phase than in an agarose hydrogel modified to have the same average pore size. According to modelling, the strong retardation is primarily due to the fact that hydrodynamic interaction with the continuous monoolein membrane is a stronger source of friction than the steric interactions (collisions) with discrete gel fibres. A secondary effect is that the regular liquid crystal has a narrower pore-size distribution than the random network of the agarose gel. In agreement with experiments, these two effects together predict that the retardation in the cubic phase is a 30-fold stronger than in an agarose gel with the same average pore radius.
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| 7. |
- Voinova, Marina V., 1958, et al.
(author)
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On dissipation of quartz crystal microbalance as a mechanical spectroscopy tool
- 2004
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In: Spectroscopy. - 0712-4813. ; 18:4, s. 537-544
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Journal article (peer-reviewed)abstract
- We report on theoretical analysis of dissipative effects in quartz crystal resonator applications to the dynamics of complex biological fluids and soft polymer films. As a mechanical spectroscopy tool, the quartz resonator can probe the storage and loss moduli μ(ω) of a thin material sample in small amplitude oscillations where polymers exhibit linear viscoelasticity. We show how viscosity (internal friction) and slippage (interfacial friction) of the sample affect the acoustical characteristics of the quartz resonator. With respect to biosensor's application, we present rigorous expressions for the resonant frequency and damping of the quartz crystal which allow to quantify friction effects and even distinguish between them in resonator measurements performing on various frequencies. Possible application of the results in electronic nose and electronic tongue sensors is discussed.
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| 8. |
- Voinova, Marina V., 1958
(author)
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On Mass Loading and Dissipation Measured with Acoustic Wave Sensors: A Review
- 2009
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In: Journal of Sensors. ; 2009
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Journal article (peer-reviewed)abstract
- We summarize current trends in the analysis of physical properties (surface mass density, viscosity, elasticity, friction, and charge) of various thin films measured with a solid-state sensor oscillating in a gaseous or liquid environment. We cover three different types of mechanically oscillating sensors: the quartz crystal microbalance with dissipation (QCM-D) monitoring, surface acoustic wave (SAW), resonators and magnetoelastic sensors (MESs). The fourth class of novel acoustic wave (AW) mass sensors, namely thin-film bulk acoustic resonators (TFBARs) on vibrating membranes is discussed in brief. The paper contains a survey of theoretical results and practical applications of the sensors and includes a comprehensive bibliography.
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| 9. |
- Voinova, Marina V., 1958, et al.
(author)
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The quartz crystal microbalance
- 2011
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In: Chemical sensors: Comprehensive sensor technology, Vol. 4: Solid state devices, Ch. 9 (68 pages). - New York : Momentum Press. - 9781606502334
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Book chapter (other academic/artistic)abstract
- Quartz crystal resonators are among the most popular acoustic sensor devices. In this chapter we discuss the basic principles of the quartz crystal microbalance (QCM) technique and review current approaches to analyzing QCM measurements. We also discuss a number of practical applications of the QCM device and provide selected examples of new trends.
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