A closer look at erythrocytes in motion

Blood analysis is usually the first step involved in the diagnosis of various diseases, such as typhoid and malaria. The biochemical and cellular equilibrium of blood is very sensitive to physiological variations occurring in the body at various disease stages. Thus, a fast and accurate examination of blood properties is essential. The morphological and biochemical changes in erythrocytes are used as  the pathological signatures of various diseases.

Flow cytometry is used  to examine blood cells, which requires hydrodynamic sheath flow alignment and fluorescence antibody labelling, making it time-consuming and expensive. Advanced light scattering techniques (such as digital holography) are often seen as suitable alternatives, as they provide fast and label-free measurements.

In a recent Lab On A Chip articleNetti et al. from the Italian Institute of Technology, in collaboration with scientists from Germany and Russia, presented a camera-based light scattering approach, coupled with a viscoelasticity -induced cell migration technique. This new system is used to characterise the morphological properties of erythrocytes in microfluidic flows.

They obtained light scattering profiles (LSPs) of individual living cells in microfluidic flows over a wide angular range and matched them with scattering simulations to characterise their morphological properties. A healthy erythrocyte diameter lies between 6 and 9 µm. The diameter values obtained from the experiment lie between 7 and 8.3 µm, which is in good agreement with the existing literature.

‘The results demonstrate the ability of a rapid and cost effective way to measure the average dimensions of an erythrocyte population which can be easily related to the health of a patient,’ concludes Netti.



To gain deeper insight into LSP acquisition and simulation, you can read the full article for free* by following the link below.
Optical signature of erythrocytes by light scattering in microfluidic flows
D. Dannhauser, D. Rossi, F. Causa, P. Memmolo, A. Finizio, T. Wriedt, J. Hellmers, Y. Eremin, P. Ferraro and   P. A. Netti
Lab Chip, 2015,15, 3278-3285
DOI: 10.1039/C5LC00525F

*Access is free until 27/09/2015 through a registered RSC account.
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One-Touch-Activated Blood Multidiagnostic System using a Minimally Invasive Hollow Microneedle Integrated with a Paper-Based Sensor 


 
   
 
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Cell pinballs in microfluidic channels

an article by Claire Weston, PhD student at Imperial College London

Researchers from the Kaneko Higashimori Lab at Osaka University and the Arai Lab at Nagoya University have observed an interesting phenomenon when studying red blood cells in microfluidic channels. Instead of flowing along the channel in a smooth motion as expected, some cells bounce back and forth between the channel walls in a pinball-like motion at much slower speed. In addition to these ‘cell pinballs’, there are also cells that move at a similar reduced speed, but don’t hit the channel walls.

This altered behaviour could have detrimental effects on microfluidic devices, caused by non-uniform movement of the cells in the channels. In order to prevent these potential problems, the authors have investigated the cause of this behaviour. They noted that cell pinballs only occur when the saline medium is hypotonic, as this causes the cells to inflate due to intake of water. By attaching microbeads to the cells and using a high speed camera, the motion of the cells were studied in more detail. The pinball cells rotated clockwise as they moved to the left of the channel and anticlockwise as they moved to the right of the channel (relative to the direction of the flow).

This observation, combined with the knowledge that the cells were inflated in the hypotonic solution, led the authors to believe that the pinball-motion was occurring due to both the shape of the red blood cell and contact with the channel walls. 3D images obtained using confocal microscopy showed that the upper and lower surfaces of the cells were flattened, confirming that the cells were in contact with the walls.

By studying the different possible deformations of the inflated red blood cells when subjected to flow, the authors found that the contact line (between the cell and wall) and the centre line of the cell were not the same. This explains both types of unexpected cell motion – if the contact line is downstream of the centre line, the cell is unstable to rotational motion and this causes it to move at an angle to the flow, leading to the pinball cells, whereas if the contact line is upstream of the centre line the cell is stable to rotational motion and no displacement occurs, leading to the slow moving non-pinball cells.

From these studies, the authors were able to propose mechanisms that successfully explained the two types of altered red blood cell behaviour in hypotonic solutions, and hopefully in the future this should allow microfluidic systems to be used which will avoid this pinball-motion occurring.



To download the full article for free* click the link below:
Cell pinball: phenomenon and mechanism of inertia-like cell motion in a microfluidic channel
Ryo Murakami, Chia-Hung Dylan Tsai, Makoto Kaneko, Shinya Sakuma and Fumihito Arai
Lab Chip, 2015, 15, 3307-3313
DOI: 10.1039/ c5lc00535c

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About the webwriter

Claire Weston is a PhD student in the Fuchter Group, at Imperial College London. Her work is focused on developing novel photoswitches and photoswitchable inhibitors.

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*Access is free until 06/09/2015  through a registered RSC account.

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µ-Med A 2015 workshop

An international workshop on microsystems technologies for African health

µ-Med A 2015, an international workshop on microsystems technologies for African health. This interesting workshop will be held during 16-19 September 2015 at Protea hotel, Stellenbosch, South Africa.

The event will bring together researchers, technologists, entrepreneurs, non-governmental organizations and funding bodies to interact on the latest developments and future trends in the multidisciplinary field of microsystems technology.

The workshop will focus on the following themes:

  • Burden of disease in Africa
  • Microfluidic diagnostic technologies
  • Point of care diagnostics
  • Paper based diagnostics

Feel free to read more about the success of the first workshop held in 2011.


Register now and contribute to the efforts to improve health in Africa!


For additional information, please visit µ-Med A website.

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3D Bio-etching is here!

3D technology has revolutionised the entertainment industry by offering viewers the experience of being part of the action, going on in a movie rather than simply watching it. Thanks to 3D technology, we can sky walk hand in hand with George Clooney in ‘Gravity’.

Microfluidics setup for 3D bioetching

The history of 3D technology can be drawn all the way back to the invention of the stereoscope by David Brewster in 1844. Last two decades have seen 3D technology replacing 2D in all walks of life, ranging from entertainment, physics, microelectronics, tissue engineering and regenerative medicine. For e.g., microelectromechanosensors (MEMS) are 3D devices produced by using soft lithography techniques. MEMS installed in air-bags in the cars have saved thousands of lives by sensing pressure levels during accidents.

Can we use 3D technology to have a better look at the complex events happening at cellular level? One of the major challenges in tissue engineering is that the conventional approaches are mainly limited to 2D monolayers systems and do not allow manipulation of complex multilayer tissue. Cells grown on 2D substrates may respond and differentiate distinctly than those in more physiologically relevant 3D environments. The emergence of 3D technology has enabled scientists to mimic the exact cellular environments and helped to provide better insights into the cell signalling, migration and differentiation in cells.

One of the ways of mimicking the cellular architectures is bio-etching which involves subtractive manufacturing. Bioetching of monolayers of cells in response to laser cuts or scratch assays is achieved by using 2D cell culture studies. But the actual biological systems such as tissues and organs are much more complex and cannot be mimicked using simple monolayers. For long time, scientists have been working on developing better technologies to address this problem. One of the ways to achieve this is 3D bio-etching.

William C. Messner et al. from Tufts University in a recent article in Lab on a Chip explain the utility of 3D bioetching technique to create and shape 3D composite tissues using a microfluidics based approach. The ability to shape the 3D form of multicellular tissues and to control 3D stimulation will have a high impact on tissue engineering and regeneration applications in bioengineering and medicine as well as provide significant improvements of highly complex 3D integrated multicellular biosystems.


Can 3D bio-etching help us to design tissue architecture of our choice mimicking different biological events? Find out by reading the full paper for free* using the link below:

3D bio-etching of a complex composite-like embryonic tissue
Melis Hazar, Yong Tae Kim, Jiho Song, Philip R. LeDuc, Lance A. Davidson and William C. Messner
Lab Chip, 2015, Advance Article
DOI: 10.1039/C5LC00530B


*Access is free through a registered RSC account.

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2015 Art in Science Competition

The µTAS 2015 Conference is featuring an Art in Science competition titled Under the Looking Glass: Art from the World of Small Science

Deadline 10th October 2015 at 23:59 Honolulu, Hawaii, USA time

Since the earliest publications of the scientific world, the aesthetic value of scientific illustrations and images has been critical to many researchers. The illustrations and diagrams of earlier scientists such as Galileo and Da Vinci have become iconic symbols of science and the scientific thought process.

In current scientific literature, many scientists consider the selection of a publication as a “cover article” in a prestigious journal to be very complimentary.

Are you attending the µTAS 2015 Conference?

Would you like your image to be featured on the cover of Lab on a Chip?

Would you like to win a financial reward?

To draw attention to the aesthetic value in scientific illustration while still conveying scientific merit, NIST and Lab On a Chip are sponsoring this annual award. Applications are encouraged from authors in attendance of the µTAS Conference and the winner will be selected by a panel of senior scientists in the field of µTAS.

Applications must show a photograph, micrograph or other accurate representation of a system that would be of interest to the µTAS community and be represented in the final manuscript or presentation given at the Conference.

They must also contain a brief caption that describes the illustration’s content and its scientific merit. The winner will be selected on the basis of aesthetic eye appeal, artistic allure and scientific merit. In addition to having the image featured on the cover of Lab on a Chip, the winner will also receive a financial award at the Conference.

Art Award Submission Process – Easy 3 Step Process

Step 1. Sign-In to the Electronic Form Using Your Abstract/Manuscript Number

Step 2. Fill in Remaining Information on Electronic Submission Form

Step 3. Upload Your Image

To read the full guidelines, please visit the competition website.

Good Luck!

You can also take a look at the winners from last year on our blog.

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2015 MicroTAS Video Competition

Lab on a Chip is proud to announce the second μTAS Video Competition, created in partnership with Dolomite Microfluidics and supported by the CBMS (the Chemical and Biological Microsystems Society).

We invite registered μTAS participants to submit short videos (see full conditions of entry below) that are either scientifically or educationally focused. Videos may be fun, artistic or just surprising and unusual in order to meet these criteria.

Dolomite Microfluidics, innovators in microfluidic solutions, have generously agreed to support this competition with $2500 worth of Dolomite equipment as the prize.

If you think you have the necessary visual science to take home the prize money, have a read of the entry conditions below!

Deadline: 9th October 2015

Video Award Submission Process – Easy 3 Step Process

Step 1. Sign-In to the Electronic Form Using Your Registration Number

Please have your Registration Number accessible. If you are unable to locate your Registration Number, please contact microtas2015@hdasan.com.

Step 2. Fill in Remaining Information on Electronic Submission Form

Please fill in remaining information on the electronic submission form including title of image and your caption.

Step 3. Upload Your Video

All entries are to be submitted online via this website as .mpg, .mp4, .mov, .avi or .wmv. Entries will not be accepted by email or post. Once your entry has been successfully uploaded and submitted, you will be given an entry number and you will be sent a confirmation email with the information you provided, minus the video. The ability to submit an video will close Friday, 9 October 2015 at 23:59 Honolulu, Hawaii, USA time (HST. GMT minus 10 hours).


Guidelines:

1. Only participants registered for the MicroTAS conference can take part and submit videos

2. Videos must be either scientific (demonstrating interesting aspects) or educational (enhancing understanding) with respect to micro- or nanofluidics

3. Videos can be presented in a fun way

4. Videos can be presented in an artistic way

5. Videos can be presented in a surprising or unusual way

6. Videos can be enhanced by audio, animations, or annotations, if necessary

7. Videos should be no longer than 2 minutes each

8. Videos should have a file size less than 25 Mbytes (please use appropriate video compression)

9. Videos must be viewable on a PC without special software (.mpg, .mp4, .mov, .avi or .wmv)

10. Videos can be uploaded between July 25 and October 9, 2015

11. All submissions are submitted on the basis that they may be used by LOC and/or CBMS for promotional purposes in any form

12. Assessment by an international panel of judges will take place at MicroTAS 2015. The judges’ decision will be final, and no discussion will be entertained.

13. The prize will be awarded at MicroTAS 2015, and a written voucher for the equipment will be handed over to the person submitting the winning entry.

Finally, just for a bit of inspiration, here’s a classic Lab on a Chip video from our YouTube channel…enjoy!


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Recognition of danger in single cells

an article by Alphonsus Ng, postdoctoral fellow at the University of Toronto

For more than a century, researchers have been studying how the body detects and defends itself against foreign invaders.1 This process relies on a series of cell-to-cell signaling, starting with the detection of common pathogen components by receptors of immune cells. For example, macrophages, a surveillance immune cell, recognize bacteria using the Toll-Like receptor 4 (TLR4), which binds to lipopolysaccharide (LPS) found in the membrane of gram-negative bacteria.

Upon recognition of danger signals, immune cells engulf and degrade the invaders and activate NF-κB, an intracellular protein that, when activated, migrates into the nucleus and turns on inflammatory response genes. For immune cells, this initiates the secretion of signaling mediators such as tumour necrosis factor (TNF), which helps remove invaders by dilating local blood vessels and recruiting other immune cells.

Although our understanding of the immune system has skyrocketed in the past two decades,2 researchers are still lacking the tools needed to study the signaling of inflammation in a highly controlled manner. Most approaches rely on bulk population measurements, in which important spatial and temporal patterns of signaling are obscured by biological noise from neighbouring cells. To address this challenge, Tino Frank and Prof. Savas Tay from ETH Zurich developed a microfluidic system that can propagate inflammatory signals from a single immune cell (sender cell) and to a population of fibroblast cells (receiver cells).3

The microfluidic device, formed from polydimethylsiloxane (PDMS), comprises a deflectable membrane sandwiched between a flow layer and a control layer. The flow layer houses supply channels and cell culture chambers, while the control layer regulates input, output, and segregation of these chambers using solenoid-actuated valves.

As shown in picture 1, the chambers for the sender cell (chamber A) and receiver cells (chamber B) can be segregated for mono culture or connected for co-culture, depending on the state of the reversible separation valve. In mono culture mode, the sender cell can be stimulated independent of the receiver cells, whereas in co-culture mode, the signaling mediators secreted by the sender cell can be broadcasted to the receiver cells via diffusion.

Valve PDMS microfluidic device for mono and co-culture

Using this system, the researchers implemented a single-cell model of inflammation arising from bacterial infection (picture 2). This model begins in mono culture mode, with a single macrophage seeded in chamber A and a population fibroblasts seeded in chamber B. Inflammation was initiated by stimulating the macrophage with short pulses of bacterial LPS, leading to the activation of NF-κB and TNF secretion. Subsequently, the device was switched to co-culture mode, allowing the secreted TNF to diffuse across the fibroblasts and activate their NF-κB signaling.

One-way communication chain mimicking an inflammatory process, with macrophage as sender and fibroblasts as receiver.

By tracking the movement of NF-κB in the nucleus of individual cells, the researchers, for the first time, mapped the spatiotemporal distribution of immune response to bacterial infection. They demonstrate that a single macrophage can activate and control over 100 fibroblasts up to 1 mm away, and that fibroblasts located farther away exhibited a time-delayed activation profile and fewer NF-κB oscillations (between the nucleus and cytoplasm). Furthermore, they observed that the NF-κB signaling in some fibroblasts can linger for up to 10 hours, demonstrating that a brief exposure to pathogenic signal can induce long-term inflammatory response in nearby cells.

In summary, Tino Frank and Prof. Savas Tay developed a microfluidic platform to study spatiotemporal dynamics of immune response in single cells. The continued investigation of these dynamics will be important for understanding of the inflammatory process and modeling of relevant signaling pathways.4


To download the full article for free* click the link below:
Automated co-culture system for spatiotemporal analysis of cell-to-cell communication
Tino Franka and Savaş Taya
Lab Chip, 2015, 15, 2192-2200
DOI: 10.1039/C5LC00182J


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References:

1. K. M. Murphy, Janeway’s immunobiology, Garland Science, 2011.
2. L. A. J. O’Neill, D. Golenbock and A. G. Bowie, Nat Rev Immunol, 2013, 13, 453-460.
3. T. Frank and S. Tay, Lab on a Chip, 2015, 15, 2192-2200.
4. M. Junkin and S. Tay, Lab on a Chip, 2014, 14, 1246-1260.

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About the webwriter

Alphonsus Ng is a postdoctoral fellow under the supervision of Dr. Aaron Wheeler in the Department of Chemistry and the Institute of Biomaterials and Biomedical Engineering at the University of Toronto. His research focuses on the development of microfluidic methods for heterogeneous immunoassays, cell-based assays, enzymatic catalysis, sample preparation for proteomics, and chemical synthesis.

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*Access is free until 24/08/2015  through a registered RSC account.

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