| 1. |
- Abbaszadehbanaeiyan, Amin, et al.
(författare)
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Design and fabrication of high-throughput application-specific microfluidic devices for studying single-cell responses to extracellular perturbations
- 2013
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Ingår i: Proc. SPIE 8765, Bio-MEMS and Medical Microdevices, 87650K. ; 8765
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Konferensbidrag (refereegranskat)abstract
- Single cell analysis techniques provide a unique opportunity of determining the intercellular heterogeneity in a cell population, which due to genotype variations and different physiological states of the cells i.e. size, shape and age, cannot be retrieved from averaged cell population values. In order to obtain high-value quantitative data from single-cell experiments it is important to have experimental platforms enabling high-throughput studies. Here, we present a microfluidic chip, which is capable of capturing individual cells in suspension inside separate traps. The device consists of three adjacent microchannels with separate inlets and outlets, laterally connected through the V-shaped traps. Vshaped traps, with openings smaller than the size of a single cell, are fabricated in the middle (main) channel perpendicular to the flow direction. Cells are guided into the wells by streamlines of the flows and are kept still at the bottom of the traps. Cells can then be exposed to extracellular stimuli either in the main or the side channels. Microchannels and traps of different sizes can be fabricated in polydimethylsiloxane (PDMS), offering the possibility of independent studies on cellular responses with different cell types and different extracellular environmental changes. We believe that this versatile high-throughput cell trapping approach will contribute to further development of the current knowledge and information acquired from single-cell studies and provide valuable statistical experimental data required for systems biology. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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| 2. |
- Abbaszadehbanaeiyan, Amin, 1983, et al.
(författare)
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Hydrodynamic Cell Trapping for High Throughput Single-Cell Applications
- 2013
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 4:4, s. 414-430
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Tidskriftsartikel (refereegranskat)abstract
- The possibility to conduct complete cell assays under a precisely controlled environment while consuming minor amounts of chemicals and precious drugs have made microfluidics an interesting candidate for quantitative single-cell studies. Here, we present an application-specific microfluidic device, cellcomb, capable of conducting high-throughput single-cell experiments. The system employs pure hydrodynamic forces for easy cell trapping and is readily fabricated in polydimethylsiloxane (PDMS) using soft lithography techniques. The cell-trapping array consists of V-shaped pockets designed to accommodate up to six Saccharomyces cerevisiae (yeast cells) with the average diameter of 4 μm. We used this platform to monitor the impact of flow rate modulation on the arsenite (As(III)) uptake in yeast. Redistribution of a green fluorescent protein (GFP)-tagged version of the heat shock protein Hsp104 was followed over time as read out. Results showed a clear reverse correlation between the arsenite uptake and three different adjusted low = 25 nL min−1, moderate = 50 nL min−1, and high = 100 nL min−1 flow rates. We consider the presented device as the first building block of a future integrated application-specific cell-trapping array that can be used to conduct complete single cell experiments on different cell types.
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| 3. |
- Abbaszadehbanaeiyan, Amin, et al.
(författare)
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Liver-lobule-on-a-chip microfluidic device for long-term maintenance of human hepatocytes
- 2017
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Ingår i: Presented at EMBEC’17 & NBC’17 (conference), 11-15 juni 2017, Tampere, Finland.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The pressing need for in vitro micro-physiological platforms for drug discovery and development has given rise to the emergence of organs-on-a-chip (OOC) microfluidic devices. The possibility of reproducing the native niche of each organ in a dynamic microenvironment offers advantages over current static 2D and 3D cell culture techniques. Constant removal of waste products and metabolites from the culture while providing a continuous flow of growth media is one of the major benefits of dynamic OOC systems. Additionally, physiological flow conditions can be introduced to the system allowing for reproduction of the vasculature parameters of organs in vitro. The liver is the main organ in the body for drug clearance and detoxification. The key role of the liver in the metabolism system of the human body makes it an interesting target organ to mimic in the dynamic OOC systems. Here we present a PDMS-based liver-lobule-on-a-chip microfluidic device designed to reproduce the geometrical as well as convection-diffusion mass transport aspects of the classic liver lobule. We cultured human induced pluripotent stem cell (hiPSC)-derived hepatocytes (CDI) in honeycomb cell culture chambers with involvement of two different extra-cellular matrix (ECM) materials. In the first approach, microfluidic devices were pre-treated with rat-tail collagen I and cell suspension was seeded in the devices afterwards. Cells were seeded in the devices with the supplemented plating medium (RPMI) and culture for 5 days. The medium was changed to the supplemented mainte-nance media (RPMI) thereafter and replaced every other day. In the second approach, we mixed the cell suspension with 20% diluted GeltrexTM (15 mg/ml) in a 1:1 ratio. Cells were seeded in the supplemented plating media (RPMI) and were kept under conditions identical to approach one during the hepatocyte maturation period. After day 5, however, the formulation of maintenance media was changed to supplemented DMEM/F12. Cultures were kept viable and functional for at least three weeks. In both scenarios cells formed 3D tissue-like structures and formation of bile canaliculi network was observed in the devices versus 2D static cultures. The compatibility of the device for drug toxicity applications and multi-cellular in vitro organotype construction is currently under exploration.
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| 4. |
- Ahmadpour, Doryaneh, 1973, et al.
(författare)
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Effect of MAPK Inhibitor on the Arsenite uptake by Aquaglyceroporin in Single Yeast Cells.
- 2013
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Ingår i: Optical Molecular Probes, Imaging and Drug Delivery.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Regulating arsenic uptake is imperative due to its carcinogenicity. Combining microfluidics, optical tweezers and fluorescence microscopy, the arsenite uptake by Fps1 using a selective kinase inhibitor is investigated using a single cell analysis platform.
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| 5. |
- Ahmadpour, Doryaneh, 1973, et al.
(författare)
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Inhibition of MAPK Hog1 Results in Increased Hsp104 Aggregate Formation Probably through Elevated Arsenite Influx into the Cells, an Approach with Numerous Potential Applications
- 2014
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Ingår i: American Journal of Molecular Biology. - : Scientific Research Publishing, Inc.. - 2161-6620 .- 2161-6663. ; 4:2, s. 59-71
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Tidskriftsartikel (refereegranskat)abstract
- Arsenic is a highly toxic and carcinogenic metalloid widely dispersed in the environment, contaminating water and soil and accumulating in crops. Paradoxically, arsenic is also part of modern therapy and employed in treating numerous ailments and diseases. Hence, inventing strategies to tune cellular arsenic uptake based on purpose is striking. Here, we describe an approach in which the arsenite uptake can be increased using a MAPK inhibitor. Employing microfluidic flow chambers in combination with optical tweezers and fluorescent microscopy, we elevated the influx of arsenite into the yeast Saccharomyces cerevisiae cells following short-term treatment with a Hog1 kinase inhibitor. The increase in arsenite uptake was followed on arsenite triggered redistribution of a reporter protein, Hsp104-GFP, which was imaged over time. The effect was even more pronounced when the yeast mother and daughter cells were analyzed disjointedly, an opportunity provided owing to single-cell analysis. Our data firstly provide a strategy to increase arsenite uptake and secondly show that arsenite triggered aggregates, previously shown to be sites of damaged proteins, are distributed asymmetrically and less accumulated in daughter cells. Inventing approaches to tune arsenite uptake has a great value for its use in environmental as well as medical applications.
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| 6. |
- Dalsbecker, Philip, 1991, et al.
(författare)
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On-chip maturation of induced pluripotent stem-cell derived hepatocytes
- 2017
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Ingår i: SelectBio Organ-on-a-Chip Europe (conference), 10-11 May 2017, Munich, Germany..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The increasing interest in induced pluripotent stem cells (iPSCs) for research towards personalized medicine fits together well with recent advances in organ-on-chip development. Here, results of on-chip maturation of iPS-derived hepatocytes in a liver-on-a-chip platform are presented. The device itself, previously described by Banaeiyan et al., is designed to mimic the lobular structure of the liver and has successfully been used for 3D culture of both hepatocellular carcinoma cells (HepG2) and iPSC-derived hepatocytes. As the next step of device validation, iPS-derived hepatic cells have been matured on-chip into functional, mature hepatocytes, expressing important markers such as albumin and forming bile canalicular structures not seen in corresponding 2D cultures. Future plans for the platform include on-chip differentiation of iPSC-derived definitive endoderm cells into mature hepatocytes. To this end, a combination of immunofluorescent and metabolic assays have been tested on said definitive endoderm cells during directed differentiation into hepatocytes in a conventional 2D culture. These assays will be used to verify the corresponding differentiation in the on-chip 3D culture.
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| 7. |
- Kögel, Benjamin, 1979, et al.
(författare)
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Integrated Tunable VCSELs With Simple MEMS Technology
- 2010
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Ingår i: Semiconductor Laser Conference (ISLC), 2010 22nd IEEE International. - 0899-9406. - 9781424456833
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Konferensbidrag (refereegranskat)abstract
- A simple MEMS technology for wafer-scale fabrication of tunable VCSELs is presented. Reflown photo-resist droplets serve as preform for making curved movable micro-mirrors. First devices show a tuning range of 15 nm with mW-output power.
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