| 1. |
- Ardabili, Sahar, et al.
(författare)
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Dean flow-coupled inertial focusing for ultra-high-throughput particle filtration
- 2010
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Ingår i: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2010, MicroTAS 2010. - 9781618390622 ; , s. 1586-1588
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Konferensbidrag (refereegranskat)abstract
- Particle manipulation represents an important and fundamental step prior to counting, sorting and detecting bio-particles. In this study, we report dean-coupled inertial focusing of particles in flows through a single curve microchannel at extremely high channel Reynold numbers (∼325). We found the lateral particle focusing position, xf to be fixed and largely independent of radius of curvature and whether particles are pre-focused (at equilibrium) entering the curvature or randomly distributed. Finally, using a single inlet, u-shaped, microchannel we demonstrate filtration of 10μm particles from 2 μm particles at throughputs several orders of magnitude higher than previously shown.
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| 2. |
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| 3. |
- Ardabili, Sahar, 1982-
(författare)
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Microfluidic bases sample preparation for blood stream infections
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microfluidics promises to re-shape the current health-care system by transferring diagnostic tools from central laboratories to close vicinity of the patient (point-of-care). One of the most important operational steps in any diagnostic platform is sample preparation, which is the main subject in this thesis. The goal of sample preparation is to isolate targets of interest from their surroundings. The work in this thesis is based on three ways to isolate bacteria: immune-based isolation, selective cell lysis, size-based separation.The first sample-preparation approach uses antibodies against lipopolysaccharides (LPS), which are surface molecules found on all gram-negative bacteria. There are two characteristics that make this surface molecule interesting. First, it is highly abundant: one bacterium has approximately a million LPS molecules on its cell-wall. Second, the molecule has a conserved region within all gram-negative bacteria, so using one affinity molecule to isolate disease-causing gram-negative bacteria is an attractive option, particularly from the point of view of sample preparation. The main challenge, however, is antigen accessibility. To address this, we have developed a treatment protocol that improves the capturing efficiency.The strategy behind selective cell lysis takes advantage of the differences between the blood-cell membrane and the bacterial cell-wall. These fundamental differences make it possible to lyse (destroy) blood-cells selectively while keeping the target of interest, here the bacteria, intact and, what is more important alive. Viability plays an important role in determining antibiotic susceptibility.Difference in size is another well-used characteristic for sample- separation. Inertial microfluidics can focus size-dependent particle at high flow-rates. Thus, particles of 10 µm diameter were positioned in precise streamlines within a curved channel. The focused particles can then be collected at defined outlets. This approach was then used to isolate white blood cells, which account for approximately 1% of the whole blood. In such a device particles of 2µm diameter (size of bacteria) would not be focused and thereby present at every outlet. To separate bacteria from blood elasto-inertial microfluidics was used. Here, e blood components are diverted to center of the channels while smaller bacteria remain in the side streams and can subsequently be separated.
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| 4. |
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| 5. |
- Faridi, Muhammad Asim, et al.
(författare)
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Elasto-inertial microfluidics for bacteria separation from whole blood for sepsis diagnostics
- 2017
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Ingår i: Journal of Nanobiotechnology. - : BioMed Central (BMC). - 1477-3155. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Bloodstream infections (BSI) remain a major challenge with high mortality rate, with an incidence that is increasing worldwide. Early treatment with appropriate therapy can reduce BSI-related morbidity and mortality. However, despite recent progress in molecular based assays, complex sample preparation steps have become critical roadblock for a greater expansion of molecular assays. Here, we report a size based, label-free, bacteria separation from whole blood using elasto-inertial microfluidics.Results: In elasto-inertial microfluidics, the viscoelastic flow enables size based migration of blood cells into a non- Newtonian solution, while smaller bacteria remain in the streamline of the blood sample entrance and can be sepa- rated. We first optimized the flow conditions using particles, and show continuous separation of 5 μm particles from 2 μm at a yield of 95% for 5 μm particle and 93% for 2 μm particles at respective outlets. Next, bacteria were continu- ously separated at an efficiency of 76% from undiluted whole blood sample.Conclusion: We demonstrate separation of bacteria from undiluted while blood using elasto-inertial microfluidics. The label-free, passive bacteria preparation method has a great potential for downstream phenotypic and molecular analysis of bacteria.
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| 6. |
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| 7. |
- Pavankumar, A. R., et al.
(författare)
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Bioanalytical advantages of a novel recombinant apyrase enzyme in ATP-based bioluminescence methods
- 2018
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 1025, s. 118-123
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasensitive measurements of intracellular ATP (intATP) based on the firefly luciferase reactions are frequently used to enumerate bacterial or mammalian cells. During clinical applications, extracellular ATP (extATP) should be depleted in biological samples since it interferes with intATP and affects the quantification of bacteria. The extATP can be eliminated by ATP-degrading enzymes but complete hydrolysis of extATP remains a challenge for today's commercial enzymes. The catalytic efficiency of ATP-degrading enzymes depends on enzyme characteristics, sample composition and the ability to deplete diphosphates, triphosphates and their complexes generated during the reaction. This phenomenon restricts the usage of bioluminescence-based ATP methods in clinical diagnostics. In light of this, we have developed a recombinant Shigella flexneri apyrase (RSFA) enzyme and analysed its ATP depletion potential with five commercial biochemical sources including potato apyrase, acid phosphatase, alkaline phosphatase, hexokinase and glycerol kinase. The RSFA revealed superior activity by completely eliminating the extracellular ATP and ATP-complexes, even in biological samples like urine and serum. Therefore, our results can potentially unwrap the chemical and bio-analytical applications of ATP-based bioluminescence tests to develop highly sensitive point-of-care diagnostics.
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| 8. |
- Periyannan Rajeswari, Prem Kumar, et al.
(författare)
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Development of microfluidic aqueous two-phase system for continuous partitioning of E. coli strains
- 2011
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Ingår i: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011. - 9781618395955 ; , s. 1329-1331
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Konferensbidrag (refereegranskat)abstract
- The interaction of bacterial cells with surrounding environment depends on its surface characteristics such as hydrophobicity, hydrophilicity balance and net charge. In this paper, aqueous two-phase system partitioning of Escherichia coli strains based on their difference in surface properties is introduced in a microfluidic system. While aqueous two-phase system is widely use to separate biomolecules on macroscale, the method has not been adapted in microfluidic system. The bacterial cells are partitioned based on their affinity for streams formed by aqueous polymers polyethylene glycol (PEG) and dextran (Dex). Partitioning efficiency of two Escherichia coli strains is currently being optimized.
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| 9. |
- Ramachandraiah, Harisha, et al.
(författare)
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Dean flow-coupled inertial focusing in curved channels
- 2014
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 8:3, s. 034117-
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Tidskriftsartikel (refereegranskat)abstract
- Passive particle focusing based on inertial microfluidics was recently introduced as a high-throughput alternative to active focusing methods that require an external force field to manipulate particles. In inertial microfluidics, dominant inertial forces cause particles to move across streamlines and occupy equilibrium positions along the faces of walls in flows through straight micro channels. In this study, we systematically analyzed the addition of secondary Dean forces by introducing curvature and show how randomly distributed particles entering a simple u-shaped curved channel are focused to a fixed lateral position exiting the curvature. We found the lateral particle focusing position to be fixed and largely independent of radius of curvature and whether particles entering the curvature are pre-focused (at equilibrium) or randomly distributed. Unlike focusing in straight channels, where focusing typically is limited to channel cross-sections in the range of particle size to create single focusing point, we report here particle focusing in a large cross-section area (channel aspect ratio 1: 10). Furthermore, we describe a simple u-shaped curved channel, with single inlet and four outlets, for filtration applications. We demonstrate continuous focusing and filtration of 10 mu m particles (with > 90% filtration efficiency) from a suspension mixture at throughputs several orders of magnitude higher than flow through straight channels (volume flow rate of 4.25ml/min). Finally, as an example of high throughput cell processing application, white blood cells were continuously processed with a filtration efficiency of 78% with maintained high viability. We expect the study will aid in the fundamental understanding of flow through curved channels and open the door for the development of a whole set of bio-analytical applications.
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| 10. |
- Zelenin, S., et al.
(författare)
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Bacteria isolation from whole blood for sepsis diagnostics
- 2011
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Ingår i: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011. - 9781618395955 ; , s. 518-520
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Konferensbidrag (refereegranskat)abstract
- Rapid and reliable detection of bloodstream infections would gain a lot from improved and straightforward isolation of highly purified bacteria from whole blood. Here, we report a microfluidics-based sample preparation strategy to continuously isolate microorganisms from whole blood for downstream analysis. The continuous-flow method takes advantage of the fact that bacteria cells have rigid cell wall enables selective and complete blood cell lysis while ~ 100% of bacteria are readily recovered. The method as a sample preparation unit offers opportunities to develop molecular based POC for sepsis diagnostics.
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