By Heather Hobbs
BRINGING YOU THE LATEST NEWS & EVENTS FROM THE SCIENCE INDUSTRY Device Offers More Realistic Study of Blood Clot Formation
Scientists at Birmingham University, UK, have developed a vein–on- a-chip model for use in research for understanding mechanisms of blood clot formation, replacing the need for animals in some studies.
Development of the device, a tiny channel including valves to ensure correct blood flow direction, was led by Dr Alexander Brill from the Institute of Cardiovascular Sciences together with Drs Daniele Vigolo and Alessio Alexiadis from the School of Chemical Engineering.
“The device is more advanced than previous models because the valves can open and close, mimicking the mechanism seen in a real vein. It also contains a single layer of cells, called endothelial cells, covering the inside of the vessel. These two advances make this vein-on-a-chip a realistic alternative to using animal models in research that focuses on how blood clots form. It is biologically reflective of a real vein, and it also recapitulates blood flow in a life- like manner,” said Dr Brill.
“Organ-on-a-chip devices, such as ours, are not only created to help researchers move away from the need for animal models, but they also advance our understanding of biology as they are more closely representative of how the human body works.”
Using the model, the research team successfully demonstrated the
role of a bridge between a molecule called von Willebrand Factor and a surface receptor on platelets called glycoprotein Ib-alpha, one of the basic mechanisms underlying venous clot formation.
Deep vein thrombosis (DVT), the development of blood clots in veins usually in the legs, can prove fatal as clots can detach and travel to the lungs, where it may block blood vessels and cause difficulty in breathing. Mechanisms of deep vein thrombosis require further research to improve clinicians’ understanding and ability to treat or prevent the condition.
“The principles of the 3Rs – to replace, reduce and refine the use of animals in research – are embedded in national and international legislation and regulations on the use of animals in scientific procedures. But there is always more that can be done. Innovations such as the new device created for use in thrombosis research are a step in the right direction,” added Dr Brill
This research, funded by the NC3R, British Heart Foundation and Wellcome was published in Frontiers in Cardiovascular Medicine.
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Graphene Reveals Surprising Magnetoresistance Response
remarkably strong response, reaching above 100% in magnetic fields of standard permanent magnets (of about 1,000 Gauss). This is a record magnetoresistivity among all the known materials.
The researchers tuned high quality graphene to its intrinsic, virgin state where there were only charge carriers excited by temperature. This created a plasma of fast-moving ‘Dirac fermions’ that exhibited high mobility despite frequent scattering. Both high mobility and neutrality of this Dirac plasma are crucial components for the reported giant magnetoresistance.
Fast-moving Dirac fermions exhibiting high mobility in the graphene (credit: University of Manchester)
Materials capable of changing resistivity under magnetic fields are highly sought after for use in numerous product designs that use tiny magnetic sensors. Such materials are rare and most metals and semiconductors only change electrical resistivity by a tiny fraction of a percent at room temperature in practically viable magnetic fields. Observation of magnetoresistance response is normally conducted on materials cooled to liquid-helium temperatures, so that electrons inside scatter less and can follow cyclotron trajectories.
Now researchers led by Professor Sir Andre Geim at the University of Manchester have been surprised to discover that graphene exhibits a
In addition to the record magnetoresistivity, the researchers also found that, at elevated temperatures, neutral graphene becomes a so-called ‘strange metal’, describing materials where electron scattering becomes ultimately fast, being determined only by the Heisenberg uncertainty principle. The behaviour of strange metals is poorly understood and remains a mystery currently under investigation worldwide.
The Manchester work added more mystery by showing that graphene also exhibits a giant linear magnetoresistance in fields above a few Tesla, which is weakly temperature dependent. This high-field magnetoresistance is again record-breaking.
Published in Nature: Giant magnetoresistance of Dirac plasma in high-mobility graphene:12.04.23 DOI 10.1038/s41586-023-05807-0
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