Self-assembled magnetic filter for highly efficient immunomagnetic separation.
We have developed a compact and inexpensive microfluidic chip, the self-assembled magnetic filter, to efficiently remove magnetically tagged cells from suspension. The self-assembled magnetic filter consists of a microfluidic channel built directly above a self-assembled NdFeB magnet. Micrometre-sized grains of NdFeB assemble to form alternating magnetic dipoles, creating a magnetic field with a very strong magnitude B (from the material) and field gradient ▽B (from the configuration) in the microfluidic channel. The magnetic force imparted on magnetic beads is measured to be comparable to state-of-the-art microfabricated magnets, allowing for efficient separations to be performed in a compact, simple device. The efficiency of the magnetic filter is characterized by sorting non-magnetic (polystyrene) beads from magnetic beads (iron oxide). The filter enriches the population of non-magnetic beads to magnetic beads by a factor of >10(5) with a recovery rate of 90% at 1 mL h(-1). The utility of the magnetic filter is demonstrated with a microfluidic device that sorts tumor cells from leukocytes using negative immunomagnetic selection, and concentrates the tumor cells on an integrated membrane filter for optical detection.
Issadore
David
D
Center for Systems Biology, Massachusetts General Hospital, 185 Cambridge St, CPZN 5206, Boston, MA 02114, USA.
Shao
Huilin
H
Chung
Jaehoon
J
Newton
Andita
A
Pittet
Mikael
M
Weissleder
Ralph
R
Lee
Hakho
H
D000818:Animals; D045744:Cell Line, Tumor; D004867:Equipment Design; D006801:Humans; D018189:Immunomagnetic Separation / Q000191:economics / Q000295:instrumentation*; D007962:Leukocytes / Q000166:cytology; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000191:economics / Q000295:instrumentation*