Magnetic levitation separates living cells from the dead

摘要

A FORM of magnetic levitation can separate living and dead cells without altering or damaging them in any way. The process could be used for everything from drug discovery to tissue engineering. Cells normally sink to the bottom of the fluid they are in. Gozde Durmus at Stanford University in California and her colleagues have developed a way of "levitating" them by using magnetism. "Everything on Earth is magnetic," says Durmus. Her team puts cells in a fluid containing ions of the rare earth metal gadolinium, which is weakly magnetic, or paramagnetic. This form of gadolinium is non-toxic, and is injected into people to improve contrast in MRI images. The fluid is then put inside a glass tube with cheap, simple magnets above and below it. The end result is an upward magnetic force on the cells that opposes gravity, so they float in the tube at a level that depends on their density.