| 1. |
- Mikus, Maria, et al.
(författare)
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Allergome-wide peptide microarrays enable epitope deconvolution in allergen-specific immunotherapy
- 2020
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Ingår i: Journal of Allergy and Clinical Immunology. - : Mosby Inc.. - 0091-6749 .- 1097-6825.
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Tidskriftsartikel (refereegranskat)abstract
- Background: The interaction of allergens and allergen-specific IgE initiates the allergic cascade after crosslinking of receptors on effector cells. Antibodies of other isotypes may modulate such a reaction. Receptor crosslinking requires binding of antibodies to multiple epitopes on the allergen. Limited information is available on the complexity of the epitope structure of most allergens. Objectives: We sought to allow description of the complexity of IgE, IgG4, and IgG epitope recognition at a global, allergome-wide level during allergen-specific immunotherapy (AIT). Methods: We generated an allergome-wide microarray comprising 731 allergens in the form of more than 172,000 overlapping 16-mer peptides. Allergen recognition by IgE, IgG4, and IgG was examined in serum samples collected from subjects undergoing AIT against pollen allergy. Results: Extensive induction of linear peptide-specific Phl p 1– and Bet v 1–specific humoral immunity was demonstrated in subjects undergoing a 3-year-long AIT against grass and birch pollen allergy, respectively. Epitope profiles differed between subjects but were largely established already after 1 year of AIT, suggesting that dominant allergen-specific antibody clones remained as important contributors to humoral immunity following their initial establishment during the early phase of AIT. Complex, subject-specific patterns of allergen isoform and group cross-reactivities in the repertoires were observed, patterns that may indicate different levels of protection against different allergen sources. Conclusions: The study highlights the complexity and subject-specific nature of allergen epitopes recognized following AIT. We envisage that epitope deconvolution will be an important aspect of future efforts to describe and analyze the outcomes of AIT in a personalized manner.
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| 2. |
- Christakou, Athanasia, et al.
(författare)
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Characterization of natural killer cell immune surveillance against solid liver tumors
- 2015
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Ingår i: MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - : Chemical and Biological Microsystems Society. - 9780979806483 ; , s. 915-917
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a method for investigating natural killer (NK) cell aggression against ultrasound-assisted human hepatocellular carcinoma (HCC) HepG2 solid tumors in a multi-well microdevice. We quantify the activity of human primary IL-2 activated NK cells against HepG2 tumors for up to five days and we present the correlation between NK cell numbers versus average tumor volume and final tumor outcome (growth or defeat). We suggest future applications on formation of tumors originated from primary tumors cells and other tumor components as well as primary NK originating from the patient for use in personalized immunotherapy.
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| 3. |
- Christakou, Athanasia. E., et al.
(författare)
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Aggregation and long-term positioning of cells by ultrasound in a multi-well microchip for high-resolution imaging of the natural killer cell immune synapse
- 2011
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Ingår i: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011. - 9781618395955 ; , s. 329-331
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Konferensbidrag (refereegranskat)abstract
- In this study we investigate the ability of Natural Killer (NK) cells to form ultrasound-mediated intercellular contacts with target cells in a multi-well microdevice by high-resolution confocal-microscopy imaging of inhibitory immune synapses. Furthermore, we compare the NK-Target cell cluster migration with and without ultrasound actuation. Experiments indicate that clusters of cells are positioned and maintained centered in the wells for 17 hours when they are exposed continuously to ultrasound. Our system can be used for both screening high numbers of events in low resolution and also for high resolution imaging of long term cell-cell interactions.
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| 4. |
- Christakou, Athanasia E., et al.
(författare)
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Characterization of natural killer cells' cytotoxic heterogeneity using an array of sono-cages
- 2012
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Ingår i: Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012. - : Chemical and Biological Microsystems Society. - 9780979806452 ; , s. 1555-1557
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Konferensbidrag (refereegranskat)abstract
- Using a multi-well device as an array of sono-cages for single cell analysis, we quantify for the first time the heterogeneity of natural killer (NK) cells' cytotoxic response against cancer cells. We report a fraction of inactive NK cells within the tested population (36%), as well as the existence of few 'serial killers' that eliminate up to six targets during 4 hours. We also characterize the multi-well acoustic device in terms of trapping efficiency at different actuation voltages, using adherent and non-adherent cell lines. We show that the acoustic forces applied on the cells can be compared to forces of biological processes (i.e. cell adherence).
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| 5. |
- Christakou, Athanasia E., et al.
(författare)
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Live cell imaging in a micro-array of acoustic traps facilitates quantification of natural killer cell heterogeneity
- 2013
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Ingår i: Integrative Biology. - : Oxford University Press (OUP). - 1757-9694 .- 1757-9708. ; 5:4, s. 712-719
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Tidskriftsartikel (refereegranskat)abstract
- Natural killer (NK) cells kill virus-infected or cancer cells through the release of cytotoxic granules into a tight intercellular contact. NK cell populations comprise individual cells with varying sensitivity to distinct input signals, leading to disparate responses. To resolve this NK cell heterogeneity, we have designed a novel assay based on ultrasound-assisted cell-cell aggregation in a multiwell chip allowing high-resolution time-lapse imaging of one hundred NK-target cell interactions in parallel. Studying human NK cells' ability to kill MHC class I deficient tumor cells, we show that approximately two thirds of the NK cells display cytotoxicity, with some NK cells being particularly active, killing up to six target cells during the assay. We also report that simultaneous interaction with several susceptible target cells increases the cytotoxic responsiveness of NK cells, which could be coupled to a previously unknown regulatory mechanism with implications for NK-mediated tumor elimination.
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| 6. |
- Christakou, Athanasia E., et al.
(författare)
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Solid tumor spheroid formation by temperature-controlled high voltage ultrasound in a multi-well microdevice
- 2014
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Ingår i: 18th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2014. - : Chemical and Biological Microsystems SocietyChemical and Biological Microsystems Society. - 9780979806476 ; , s. 573-575
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Konferensbidrag (refereegranskat)abstract
- In the present work we demonstrate effective 3D growth of human hepatocellular carcinoma (HCC) HepG2 cell spheroids in parallel in a multi-well microdevice actuated with high voltage ultrasound in a temperature-controlled system. We compare the spheroid formation during continuous ultrasound exposure for one week where we formed spheroids in 59% of the wells, with the spheroid formation without ultrasound actuation, where we obtained 0% spheroids. Furthermore, we present an application of the tumor spheroids for investigating natural killer (NK) cells behavior against solid tumors.
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| 7. |
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| 8. |
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| 9. |
- Christakou, Athanasia, et al.
(författare)
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Ultrasonic three-dimensional on-chip cell culture for dynamic studies of tumor immune surveillance by natural killer cells
- 2015
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry. - 1473-0197 .- 1473-0189. ; 15:15, s. 3222-31
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a simple method for three-dimensional (3D) cell culture controlled by ultrasonic standing waves in a multi-well microplate. The method gently arranges cells in a suspension into a single aggregate in each well of the microplate and, by this, nucleates 3D tissue-like cell growth for culture times between two and seven days. The microplate device is compatible with both high-resolution optical microscopy and maintenance in a standard cell incubator. The result is a scaffold- and coating-free method for 3D cell culture that can be used for controlling the cellular architecture, as well as the cellular and molecular composition of the microenvironment in and around the formed cell structures. We demonstrate the parallel production of one hundred synthetic 3D solid tumors comprising up to thousands of human hepatocellular carcinoma (HCC) HepG2 cells, we characterize the tumor structure by high-resolution optical microscopy, and we monitor the functional behavior of natural killer (NK) cells migrating, docking and interacting with the tumor model during culture. Our results show that the method can be used for determining the collective ability of a given number of NK cells to defeat a solid tumor having a certain size, shape and composition. The ultrasound-based method itself is generic and can meet any demand from applications where it is advantageous to monitor cell culture from production to analysis of 3D tissue or tumor models using microscopy in one single microplate device.
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| 10. |
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| 11. |
- Fornell, Anna, et al.
(författare)
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An intra-droplet particle switch for droplet microfluidics using bulk acoustic waves
- 2017
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- To transfer cell- and bead-assays into droplet-based platforms typically requires the use of complex microfluidic circuits, which calls for methods to switch the direction of the encapsulated particles. We present a microfluidic chip where the combination of acoustic manipulation at two different harmonics and a trident-shaped droplet-splitter enables direction-switching of microbeads and yeast cells in droplet microfluidic circuits. At the first harmonic, the encapsulated particles exit the splitter in the center daughter droplets, while at the second harmonic, the particles exit in the side daughter droplets. This method holds promises for droplet-based assays where particle-positioning needs to be selectively controlled.
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| 12. |
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| 13. |
- Iranmanesh, Ida, et al.
(författare)
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Acoustic micro-vortexing of fluids, beads and cells in disposible microfluidic chips
- 2015
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Ingår i: MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - : Chemical and Biological Microsystems Society. - 9780979806483 ; , s. 1005-1007
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Konferensbidrag (refereegranskat)abstract
- In this paper we demonstrate a multi-functional platform using ultrasound for vortexing of 20-μl volumes of different samples in polymer-based disposable chips. The method enables different vortexing functions such as mixing laminar flows, resuspension of a micro-pellet of magnetic beads as well as cell lysis for DNA extraction. The device consists of an inexpensive low-frequency, high power, horn-shaped langevin transducer which is typically used for cell disruption in larger volumes. By controlling the operating time of this device (from fractions of a second up to a minute) different functions can be achieved. In addition, to avoid the high-power-induced heating, a simple cooling system is used as a chip holder consisting of a PC fan-cooled aluminum heat sink. To demonstrate a sample preparation application, we perform on-chip cell lysis and DNA extraction.
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| 14. |
- Iranmanesh, Ida, et al.
(författare)
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Acoustic micro-vortexing of fluids, particles and cells in disposable microfluidic chips
- 2016
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Ingår i: Biomedical microdevices (Print). - : Springer. - 1387-2176 .- 1572-8781. ; 18:4
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate an acoustic platform for microvortexing in disposable polymer microfluidic chips with small-volume (20 mu l) reaction chambers. The described method is demonstrated for a variety of standard vortexing functions, including mixing of fluids, re-suspension of a pellet of magnetic beads collected by a magnet placed on the chip, and lysis of cells for DNA extraction. The device is based on a modified Langevin-type ultrasonic transducer with an exponential horn for efficient coupling into the microfluidic chip, which is actuated by a low-cost fixed-frequency electronic driver board. The transducer is optimized by numerical modelling, and different demonstrated vortexing functions are realized by actuating the transducer for varying times; from fractions of a second for fluid mixing, to half a minute for cell lysis and DNA extraction. The platform can be operated during 1 min below physiological temperatures with the help of a PC fan, a Peltier element and an aluminum heat sink acting as the chip holder. As a proof of principle for sample preparation applications, we demonstrate on-chip cell lysis and DNA extraction within 25 s. The method is of interest for automating and chip-integrating sample preparation procedures in various biological assays.
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| 15. |
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| 16. |
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| 17. |
- Ohlin, Mathias, et al.
(författare)
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Analysis of trapping and streaming in an ultrasoundactuated multi-well microplate for single-cell studies
- 2012
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Ingår i: Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012. - : Chemical and Biological Microsystems Society. - 9780979806452 ; , s. 497-499
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Konferensbidrag (refereegranskat)abstract
- The dynamics of the acoustic streaming and the acoustic positioning performance in an ultrasound-actuated multiwell microplate are investigated by two different ultrasonic frequency actuation schemes: Frequency-modulation and single- frequency actuation. Our results show a significant decrease in size of the field of view when using frequencymodulation compared to single-frequency actuation, which can be used for improving the scanning time for 3D highresolution confocal microscopy by almost one order of magnitude. Furthermore, in the ultrasound-actuated multi-well microplate the high-voltage acoustic streaming show a complex time and temperature dependence and could gain stability by the use of temperature control.
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| 18. |
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| 19. |
- Ohlin, Mathias, et al.
(författare)
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Controlling acoustic streaming in a multi-well microplate for improving live cell assays
- 2011
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Ingår i: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011. - 9781618395955 ; , s. 1612-1614
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Konferensbidrag (refereegranskat)abstract
- Acoustic streaming in a multi-well microplate is investigated using two different ultrasonic actuation frequency-schemes: Single-frequency and frequency-modulation. The streaming is tracked by the use of 1 μm fluorescent polymer beads and micro-particle image velocimetry. The suspension also contained human B cells for studying the acoustic trapping and aggregation performance simultaneously with the acoustic streaming. Our results show a significant difference in the acoustic streaming between the two ultrasonic actuation schemes. A rotational fluid flow speed decreased a factor of 30 when frequency-modulation was applied compared to single-frequency actuation without apparently interfering with the acoustic cell trapping function.
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| 20. |
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| 21. |
- Ohlin, Mathias, et al.
(författare)
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Improved positioning and detectability of microparticles in droplet microfluidics using two-dimensional acoustophoresis
- 2017
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 27:8
-
Tidskriftsartikel (refereegranskat)abstract
- We have fabricated a silicon-glass two-phase droplet microfluidic system capable of generating sub 100 μm-sized, ø = (74 ± 2) μm, spherical droplets at rates of up to hundreds of hertz. By implementing a two-dimensional (2D) acoustophoresis particle-positioning method, we show a fourfold improvement in both vertical and lateral particle positioning inside the droplets compared to unactuated operation. The efficiency of the system has been optimized by incorporating aluminum matching layers in the transducer design permitting biocompatible operational temperatures (<37 °C). Furthermore, by using acoustic actuation, (99.8 ± 0.4)% of all encapsulated microparticles can be detected compared to only (79.0 ± 5.1)% for unactuated operation. In our experiments we observed a strong ordering of the microparticles in distinct patterns within the droplet when using 2D acoustophoresis; to explain the origin of these patterns we simulated numerically the fluid flow inside the droplets and compared with the experimental findings.
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| 22. |
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| 23. |
- Ohlin, Mathias, et al.
(författare)
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Influence of acoustic streaming on ultrasonic particle manipulation in a 100-well ring-transducer microplate
- 2013
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:3, s. 035008-
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Tidskriftsartikel (refereegranskat)abstract
- We characterize and quantify the performance of ultrasonic particle aggregation and positioning in a 100-well microplate. We analyze the result when operating a planar ultrasonic ring transducer at different single actuation frequencies in the range 2.20-2.40 MHz, and compare with the result obtained from different schemes of frequency-modulated actuation. Compared to our previously used wedge transducer design, the ring transducer has a larger contact area facing the microplate, resulting in lower temperature increase for a given actuation voltage. Furthermore, we analyze the dynamics of acoustic streaming occurring simultaneously with the particle trapping in the wells of the microplate, and we define an adaptive ultrasonic actuation scheme for optimizing both efficiency and robustness of the method. The device is designed as a tool for ultrasound-mediated cell aggregation and positioning. This is a method for high-resolution optical characterization of time-dependent cellular processes at the level of single cells. In this paper, we demonstrate how to operate our device in order to optimize the scanning time of 3D confocal microscopy with the aim to perform high-resolution time-lapse imaging of cells or cell-cell interactions in a highly parallel manner.
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| 24. |
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| 25. |
- Ohlin, Mathias, et al.
(författare)
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Long-term acoustophoresis at 1 MPA do not compromise cell viability
- 2015
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Ingår i: MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - : Chemical and Biological Microsystems Society. - 9780979806483 ; , s. 996-998
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Konferensbidrag (refereegranskat)abstract
- In this paper we report on the viability of cells exposed to high acoustic pressure amplitudes (>1 MPa) and long durations (one hour) in a temperature-controlled acoustofluidic microdevice. We demonstrate that A5490 lung cancer cells are not affected by the ultrasound even at pressure levels exceeding what is normally used in acoustophoresis applications, as long as the temperature and fluid streaming around the trapped cells are carefully controlled.
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| 26. |
- Ohlin, Mathias, et al.
(författare)
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Temperature-controlled MPa-pressure ultrasonic cell manipulation in a microfluidic chip
- 2015
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 15:16, s. 3341-3349
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Tidskriftsartikel (refereegranskat)abstract
- We study the temperature-independent impact on cell viability of relevant physical parameters during long-term, high-acoustic-pressure ultrasonic exposure in a microfluidic chip designed for ultrasonic-standing-wave trapping and aggregation of cells. We use a light-intensity method and 5 mum polymer beads for accurate acoustic pressure calibration before injecting cells into the device, and we monitor the viability of A549 lung cancer cells trapped during one hour in an ultrasonic standing wave with 1 MPa pressure amplitude. The microfluidic chip is actuated by a novel temperature-controlled ultrasonic transducer capable of keeping the temperature stable around 37 °C with an accuracy better than ±0.2 °C, independently on the ultrasonic power and heat produced by the system, thereby decoupling any temperature effect from other relevant effects on cells caused by the high-pressure acoustic field. We demonstrate that frequency-modulated ultrasonic actuation can produce acoustic pressures of equally high magnitudes as with single-frequency actuation, and we show that A549 lung cancer cells can be exposed to 1 MPa standing-wave acoustic pressure amplitudes for one hour without compromising cell viability. At this pressure level, we also measure the acoustic streaming induced around the trapped cell aggregate, and conclude that cell viability is not affected by streaming velocities of the order of 100 mum s(-1). Our results are important when implementing acoustophoresis methods in various clinical and biomedical applications.
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| 27. |
- Ohlin, Mathias, 1984-, et al.
(författare)
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Two-dimensional acoustic focusing of microparticles in two-phase droplet-based microfluidic systems for improved particle positioning within spherical droplets
- 2016
-
Konferensbidrag (refereegranskat)abstract
- We have fabricated a silicon-glass microfluidic two-phase droplet generator capable of generating sub 100-micrometer-sized (⌀ ൌ74 μm ± 2 μm) spherical droplets at rates up to hundreds of hertz (298 Hz ± 85 Hz). Furthermore, we have implemented a two-dimensional acoustic focusing technique into the device. Here, we show that applying the focusing to 10 μm sized polystyrene particles during the droplet generation step, results in a fourfold improvement of the particle positioning (centricity) within the generated droplets compared to the unactuated control. Finally, the efficiency of the system has been optimized by incorporating aluminum matching layers in the transducer design permitting biocompatible operational temperatures (<37°C).
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| 28. |
- Ohlin, Mathias, 1984-, et al.
(författare)
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Two-dimensional acoustic focusing of microparticles in two-phase droplet-based microfluidic systems increases particle detectability
- 2016
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Ingår i: 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016. - 9780979806490 ; , s. 713-714
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Konferensbidrag (refereegranskat)abstract
- We have fabricated a silicon-glass two-phase droplet-based microfluidic system and implemented two-dimensional acoustic focusing prior to droplet generation as well as continuously throughout the whole system to increase particle detectability. Using acoustic focusing we have effectively minimized sedimentation of the encapsulated particles and thereby increased particle detectability by as much as 44% compared to unactuated operation of the system.
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| 29. |
- Ohlin, Mathias, 1984-
(författare)
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Ultrasonic Fluid and Cell Manipulation
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the last decade, ultrasonic manipulation has matured into an important tool with a wide range of applications, from fundamental cell biological research to clinical and industrial implementations. The contactless nature of ultrasound makes it possible to manipulate living cells in a gentle way, e.g., for positioning, sorting, and aggregation. However, when manipulating cells using ultrasound, especially using high acoustic amplitudes, a great deal of heat can be generated. This constitutes a challenge, since the viability of cells is dependent on a stable physiological temperature around 37°C. In this Thesis we present applications of ultrasonic manipulation of fluids, particles, and cells in temperature-controlled micrometer-sized devices fabricated using well established etching techniques, directly compatible with high-resolution fluorescence microscopy. Furthermore, we present ultrasonic manipulation in larger up to centimeter-sized devices optimized for fluid mixing and cell lysis. In the present work, two new ultrasonic manipulation platforms have been developed implementing temperature control. These platforms are much improved with increased performance and usability compared to previous platforms. Also, two new ultrasonic platforms utilizing low-frequency ultrasound for solubilization and cell lysis of microliter-volumed and milliliter-volumed samples have been designed and implemented. We have applied ultrasound to synchronize the interaction between large numbers of immune, natural killer cells, and cancer cells to study the cytotoxic response, on a single cell level. A heterogeneity was found among the natural killer cell population, i.e., some cells displayed high cytotoxic response while others were dormant. Furthermore, we have used temperature-controlled ultrasound to form up to 100, in parallel, solid cancer HepG2 tumors in a glass-silicon multi-well microplate. Next, we investigated the immune cells cytotoxic response against the solid tumors. We found a correlation between the number of immune cells compared to the size of the tumor and the cytotoxic outcome, i.e., if the tumor could be defeated. Finally, the effect of high acoustic pressure amplitudes in the MPa-range on cell viability has been studied in a newly developed platform optimized for long-term stable temperature control, independent on the applied ultrasound power. Lastly, we present two applications of ultrasonic fluid mixing and lysis of cells. One platform is optimized for small microliter-sized volumes in plastic disposable chips and another is optimized for large milliliter-sized volumes in plastic test tubes. The latter platform has been implemented for clinical sputum sample solubilization and cell lysis for genomic DNA extraction for subsequent pathogen detection
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| 30. |
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| 31. |
- Olofsson, Karl, et al.
(författare)
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Acoustic formation of multicellular tumor spheroids enabling on-chip functional and structural imaging
- 2018
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry. - 1473-0197 .- 1473-0189. ; 18:16, s. 2466-2476
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the complex 3D tumor microenvironment is important in cancer research. This microenvironment can be modelled in vitro by culturing multicellular tumor spheroids (MCTS). Key challenges when using MCTS in applications such as high-throughput drug screening are overcoming imaging and analytical issues encountered during functional and structural investigations. To address these challenges, we use an ultrasonic standing wave (USW) based MCTS culture platform for parallel formation, staining and imaging of 100 whole MCTS. A protein repellent amphiphilic polymer coating enables flexible production of high quality and unanchored MCTS. This enables high-content multimode analysis based on flow cytometry and in situ optical microscopy. We use HepG2 hepatocellular carcinoma, A498 and ACHN renal carcinoma, and LUTC-2 thyroid carcinoma cell lines to demonstrate (i) the importance of the ultrasound-coating combination, (ii) bright field image based automatic characterization of MTCS, (iii) detailed deep tissue confocal imaging of whole MCTS mounted in a refractive index matching solution, and (iv) single cell functional analysis through flow cytometry of single cell suspensions of disintegrated MTCS. The USW MCTS culture platform is customizable and holds great potential for detailed multimode MCTS analysis in a high-content manner.
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| 32. |
- Tenje, Maria, et al.
(författare)
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Particle Manipulation Methods in Droplet Microfluidics
- 2018
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 90:3, s. 1434-1443
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Tidskriftsartikel (refereegranskat)abstract
- This Feature article describes the different particle manipulation techniques available in the droplet microfluidics tool-box to handle particles encapsulated inside droplets and to manipulate whole droplets. We address the advantages and disadvantages of the different techniques to guide new users.
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| 33. |
- Vanherberghen, Bruno, et al.
(författare)
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Ultrasound-controlled cell aggregation in a multi-well chip
- 2010
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 10:20, s. 2727-2732
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a microplate platform for parallelized manipulation of particles or cells by frequency-modulated ultrasound. The device, consisting of a silicon-glass microchip and a single ultrasonic transducer, enables aggregation, positioning and high-resolution microscopy of cells distributed in an array of 100 microwells centered on the microchip. We characterize the system in terms of temperature control, aggregation and positioning efficiency, and cell viability. We use time-lapse imaging to show that cells continuously exposed to ultrasound are able to divide and remain viable for at least 12 hours inside the device. Thus, the device can be used to induce and maintain aggregation in a parallelized fashion, facilitating long-term microscopy studies of, e.g., cell-cell interactions.
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| 34. |
- Werr, Gabriel, 1991-, et al.
(författare)
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Integrated thin film resistive sensors for in situ temperature measurements in an acoustic trap
- 2019
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP PUBLISHING LTD. - 0960-1317 .- 1361-6439. ; 29:9, s. 140-141
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Tidskriftsartikel (refereegranskat)abstract
- This work presents an acoustic trap with integrated thin film sensors to monitor temperature variations during operation. The acoustic trap is wet-etched in glass with a thermally bonded glass lid and the thin-film sensors are integrated during fabrication. We evaluated the performance of the integrated temperature sensors and measured a temperature sensitivity of +/- 0.01 degrees C and confirmed that the read-out of the thin film sensors was not affected neither by the ionic conductivity of the solution nor the addition of microparticles into the acoustic trap. From the experiments we observed a temperature increase of the acoustic trap during operation as a result of the dissipative heating of the the piezoelectric element used to actuate the trap. We also showed that when external convective cooling was applied to the system, the temperature increase of the acoustic trap was higher than the temperature increase of the piezoelectric element itself. This shows the importance of using integrated temperature sensors in acoustic trapping to monitor the local environmental conditions.
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| 35. |
- Wiklund, Martin, et al.
(författare)
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Acoustofluidics 14 : Applications of acoustic streaming in microfluidic devices
- 2012
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 12:14, s. 2438-2451
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In part 14 of the tutorial series "Acoustofluidics - exploiting ultrasonic standing wave forces and acoustic streaming in microfluidic systems for cell and particle manipulation", we provide a qualitative description of acoustic streaming and review its applications in lab-on-a-chip devices. The paper covers boundary layer driven streaming, including Schlichting and Rayleigh streaming, Eckart streaming in the bulk fluid, cavitation microstreaming and surface-acoustic-wave-driven streaming.
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| 36. |
- Wiklund, Martin, et al.
(författare)
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On-chip acoustic sample preparation for cell studies and diagnostics
- 2013
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Ingår i: Proceedings of Meetings on Acoustics. - : Acoustical Society of America (ASA). ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- We describe a novel platform for acoustic sample preparation in microchannels and microplates. The utilized method is based on generating a multitude of acoustic resonances at a set of different frequencies in microstructures, in order to accurately control the migration and positioning of particles and cells suspended in fluid channels and chambers. The actuation frequencies range from 30 kHz to 7 MHz, which are applied simultaneously and/or in sweeps. We present two devices: A closed microfluidic chip designed for pre-alignment, size-based separation, isolation, up-concentration and lysis of cells, and an open multi-well microplate designed for parallel aggregation and positioning of cells. Both devices in the platform are compatible with high-resolution live-cell microscopy, which is used for fluorescence-based optical characterization. Two bioapplications are demonstrated for each of the devices: The first device is used for size-selective cell isolation and lysis for DNA-based diagnostics, and the second device is used for quantifying the heterogeneity in cytotoxic response of natural killer cells interacting with cancer cells.
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| 37. |
- Wiklund, Martin, et al.
(författare)
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Ultrasound-Induced Cell-Cell Interaction Studies in a Multi-Well Microplate
- 2014
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 5:1, s. 27-49
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Forskningsöversikt (refereegranskat)abstract
- This review describes the use of ultrasound for inducing and retaining cell-cell contact in multi-well microplates combined with live-cell fluorescence microscopy. This platform has been used for studying the interaction between natural killer (NK) cells and cancer cells at the level of individual cells. The review includes basic principles of ultrasonic particle manipulation, design criteria when building a multi-well microplate device for this purpose, biocompatibility aspects, and finally, two examples of biological applications: Dynamic imaging of the inhibitory immune synapse, and studies of the heterogeneity in killing dynamics of NK cells interacting with cancer cells.
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