Separating plasma from whole blood is an important step in measuring viral loads when monitoring infected patients. If you don’t have a centrifuge on hand, this continuous to be a slow process that allows for only small samples to be rapidly analyzed, and so not very useful in mobile applications and in remote environments.
The other option, membranes that filter objects within certain sizes tend to clog up, so researchers at University of Pennsylvania developed a new filter mechanism that uses gravity to continuously clean the filter and allow for larger blood samples to be separated. They tested their new system using blood samples with different HIV loads and showed that the device separates out the plasma well enough for high efficiency nucleic acid amplification.
From the study abstract in Analytical Chemistry:
This plasma separator consists of an asymmetric, porous, polysulfone membrane housed in a disposable chamber. The separation process takes advantage of both gravitational sedimentation of blood cells and size exclusion-based filtration. The plasma separator demonstrated a “blood in-plasma out” capability, consistently extracting 275 ±33.5 ul of plasma from 1.8 ml of undiluted whole blood in less than 7 min. The device was used to separate plasma laden with HIV viruses from HIV virus-spiked whole blood with recovery efficiencies of 95.5% ± 3.5%, 88.0% ± 9.5%, and 81.5% ± 12.1% for viral loads of 35,000, 3,500 and 350 copies/ml, respectively.
Analytical Chemistry: Membrane-based, sedimentation-assisted plasma separator for point-of-care applications
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