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.
Center for Systems Biology, Massachusetts General Hospital, 185 Cambridge St, CPZN 5206, Boston, MA 02114, USA.
David
D
Issadore
Huilin
H
Shao
Jaehoon
J
Chung
Andita
A
Newton
Mikael
M
Pittet
Ralph
R
Weissleder
Hakho
H
Lee
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*