| 1. |
- Xavier, Miguel, et al.
(författare)
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Label-free enrichment of primary human skeletal progenitor cells using deterministic lateral displacement
- 2019
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 19:3, s. 513-523
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Tidskriftsartikel (refereegranskat)abstract
- Skeletal stem cells (SSCs) are present in bone marrow (BM) and offer great potential for bone regenerative therapies. However, in the absence of a unique marker, current sorting approaches remain challenging in the quest for simple strategies to deliver SSCs with consistent regeneration and differentiation capacities. Microfluidics offers the possibility to sort cells marker-free, based on intrinsic biophysical properties. Recent studies indicate that SSCs are stiffer than leukocytes and are contained within the larger cell fraction in BM. This paper describes the use of deterministic lateral displacement (DLD) to sort SSCs based on cell size and stiffness. DLD is a technology that uses arrays of micropillars to sort cells based on their diameter. Cell deformation within the device can change the cell size and affect sorting - here evidenced using human cell lines and by fractionation of expanded SSCs. Following sorting, SSCs remained viable and retained their capacity to form clonogenic cultures (CFU-F), indicative of stem cell potential. Additionally, larger BM cells showed enhanced capacity to form CFU-F. These findings support the theory that SSCs are more abundant within the larger BM cell fraction and that DLD, or other size-based approaches, could be used to provide enriched SSC populations with significant implications for stem cell research and translation to the clinic.
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| 2. |
- Akbari, Elham, et al.
(författare)
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SEPARATION OF SINGLETS AND CLUSTERS OF GROUP A STREPTOCOCCI USING DETERMINISTIC LATERAL DISPLACEMENT AND FILTER SONICATION
- 2022
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Ingår i: MicroTAS 2022 - 26th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419048 ; , s. 306-307
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Konferensbidrag (refereegranskat)abstract
- Differences in morphologies of bacteria and bacteria clusters are thought to contribute to their virulence and colonization. However, the conventional standard cell biological methods cannot separate bacteria and bacteria clusters based on their morphologies and sizes, making studies of the underlying mechanisms difficult. Here we report a simple label-free method for the continuous separation of singlets and clusters, of group A streptococci, based on their size and morphology, using Deterministic Lateral Displacement and filter-sonication. In general, this opens up for the generation of cell populations with heterogenicity in cluster size and physical properties.
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| 3. |
- Barrett, Michael P., et al.
(författare)
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Microfluidics-based approaches to the isolation of African trypanosomes
- 2017
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Ingår i: Pathogens. - : MDPI AG. - 2076-0817. ; 6:4
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Forskningsöversikt (refereegranskat)abstract
- African trypanosomes are responsible for significant levels of disease in both humans and animals. The protozoan parasites are free-living flagellates, usually transmitted by arthropod vectors, including the tsetse fly. In the mammalian host they live in the bloodstream and, in the case of human-infectious species, later invade the central nervous system. Diagnosis of the disease requires the positive identification of parasites in the bloodstream. This can be particularly challenging where parasite numbers are low, as is often the case in peripheral blood. Enriching parasites from body fluids is an important part of the diagnostic pathway. As more is learned about the physicochemical properties of trypanosomes, this information can be exploited through use of different microfluidic-based approaches to isolate the parasites from blood or other fluids. Here, we discuss recent advances in the use of microfluidics to separate trypanosomes from blood and to isolate single trypanosomes for analyses including drug screening.
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| 4. |
- Beech, Jason P., et al.
(författare)
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Active Posts in Deterministic Lateral Displacement Devices
- 2019
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Ingår i: Advanced Materials Technologies. - : Wiley. - 2365-709X. ; 4:9
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Tidskriftsartikel (refereegranskat)abstract
- Using electrically connected metal-coated posts in a deterministic lateral displacement (DLD) device and applying electric fields, electrokinetics is used to tune separations, significantly decrease the critical size for separation, and increase the dynamic range with switching times on the order of seconds. The strength of DLD stems from its binary behavior. To first approximation, particles move in one out of two trajectories based on their effective size. For particles that are close to the threshold size, a small external force is sufficient to nudge the particles from one trajectory to another. The devices consist of arrays of cylindrical metal-coated SU-8 posts connected by an underlying metal layer. This allows the application of voltages at the post surfaces and the generation of electric field gradients between neighboring posts, causing polarizable particles to experience a dielectrophoretic (DEP) force. This force, which depends on the volume and polarizability of the particle, can be made sufficient to push particles from one trajectory into another. In this way, the critical size in a device, normally fixed by the geometry, can be tuned. What's more, adding DEP in this way allows for the simultaneous creation of multiple size fractions.
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| 5. |
- Beech, Jason P., et al.
(författare)
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Capillary driven separation on patterned surfaces
- 2009
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Ingår i: Proceedings of Conference, MicroTAS 2009 - The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9780979806421 ; , s. 785-787
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Konferensbidrag (refereegranskat)abstract
- Deterministic lateral displacement (DLD) is a powerful bimodal separation scheme [1] based on fluid flow through regular obstacle arrays that in its basic embodiment sends suspended particles in two different directions as a function of size. We show that without the need to seal devices and without the need for fluidic connections or pumps, particle separation can be achieved by the passive flow of a sample over a patterned surface. Risk of clogging is minimized by the movement of large particles above the obstacle array. Suitable application areas include blood fractionation and analysis of drinking water. 0
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| 6. |
- Beech, Jason P., et al.
(författare)
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Cell morphology and deformability in deterministic lateral displacement devices
- 2011
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Ingår i: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011. - 9781618395955 ; 2, s. 1355-1357
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Konferensbidrag (refereegranskat)abstract
- Deterministic Lateral Displacement (DLD) devices have been used to separate particles based on size [1] and shape [2]. Here we show how DLD devices can also be used to separate particles based on their ability to deform under shear forces. Varying experimental conditions allows us to vary the relative contributions of size, morphology and deformability. The ability to distinguish between cells based on deformability with high resolution and throughput, in cheap and simple devices, could find highly interesting and relevant applications, for example in the detection of circulating tumor cells or malaria-infected blood cells.
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| 7. |
- Beech, Jason P., et al.
(författare)
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Electrokinetic wall effect mechanisms and applications
- 2020
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Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 42-43
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Konferensbidrag (refereegranskat)abstract
- Under the application of longitudinal electric fields in microchannels, microparticles experience lift forces that push them away from the channel walls and affect their trajectories. At high frequencies (>100KHz) the dielectrophoretic forces dominate and are well understood but at lower frequencies there is little agreement as to the exact nature of the forces, how they are generated and how they vary due to the many different experimental conditions that are used in microfluidics devices. Here we present an experimental study of these mechanisms.
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| 8. |
- Beech, Jason P., et al.
(författare)
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Gravitationally driven deterministic lateral displacement devices
- 2009
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Ingår i: Proceedings of Conference, MicroTAS 2009 - The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9780979806421 ; , s. 779-781
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Konferensbidrag (refereegranskat)abstract
- Deterministic lateral displacement (DLD) is a powerful bimodal separation scheme [1] based on regular obstacle arrays that in its basic embodiment sends particles in two different directions as a function of size. We add functionality to the technique by including gravitational forces, as a perturbation to particles transported by fluid flow, and as a way of transporting the particles through a stationary fluid.
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| 9. |
- Beech, Jason P., et al.
(författare)
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Morphology-based sorting-blood cells and parasites
- 2010
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Ingår i: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2010, MicroTAS 2010. - 9781618390622 ; 2, s. 1343-1345
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Konferensbidrag (refereegranskat)abstract
- Morphology represents a hitherto unexploited source of specificity in microfluidic particle separation and may serve as the basis for label-free particle fractionation. There is a wealth of morphological changes in blood cells due to a wide range of clinical conditions, diseases, medication and other factors. Also, blood-borne parasites differ in morphology from blood cells. We present the use of Deterministic Lateral Displacement to create a chip-based, label-free diagnostic tool, capable of harvesting some of the wealth of information locked away in red blood cell morphology. We also use the device to separate the parasites that cause sleeping sickness from blood.
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| 10. |
- Beech, Jason P., et al.
(författare)
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Sample preparation for single-cell whole chromosome analysis
- 2012
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Ingår i: Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012. - 9780979806452 ; , s. 998-999
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Konferensbidrag (refereegranskat)abstract
- In this work we present an integrated system for whole chromosome analysis of single bacterium. Using whole genome barcoding techniques, which offer direct and rapid microscopic visualization of the entire genome in one field-of-view, we aim to rapidly identify individual bacterium. We are developing our device to achieve the crucial, and difficult process of isolating a bacterium, removing the DNA in one piece and transferring it to a nano-channel for visualisation. In order to achieve control over the bacteria we encapsulate them in agarose, using flow focusing. The encapsulated bacteria can then be transported in microchannels to proximity with the nanochannels and then chemically lysis can be performed. Following lysis the intact genome can be extracted and transferred to the meandering nanochannel for analysis. We believe this device holds the potential to significantly decrease analysis times for single cell, whole genome analysis with the potential of opening up for automated, high-throughput genome analysis in microfluidic systems.
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