Cells labelled with magnetic nanoparticles are useful for a number of applications, ranging from MRI to drug delivery and cancer therapy, and being able to sort said cells based on their magnetic nanoparticle loading is obviously necessary. Continuous flow methods currently exist for separating cells based on the extent of their magnetisation, but only for cells where the nanoparticles have been bound to them via specific surface markers.
In this paper Claire Wilhelm (University of Paris Diderot) and Nicole Pamme (University of Hull) make use of the other mechanism of introducing nanoparticles to the cells – exploiting the natural ability of monocytes and macrophages to engulf molecules. The team produced a free-flow microfluidic chip with an external magnet to separate the cells through five different exits, depending on the loading of magnetic nanoparticles. They demonstrated successful and efficient separation of the monocytes and macrophages, with monocytes displaying a much weaker endocytotic ability than macrophages, at rates of 10 to 100 cells per second.
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Cell sorting by endocytotic capacity in a microfluidic magnetophoresis device
Damien Robert, Nicole Pamme, Hélène Conjeaud, Florence Gazeau, Alexander Iles and Claire Wilhelm
Lab Chip, 2011, Advance Article