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Poking and prodding a cell’s innards can reveal a great deal about its properties and functions. But the tools available for such detailed manipulations have their limitations, being either invasive or insufficiently powerful. Noninvasive approaches such as optical or acoustic tweezers work well at power levels suitable for pushing molecules around, but can cause heat damage or excessive agitation when delivering enough energy to move organelles.
Magnetic tweezers—which use microscope-mounted magnets to remotely move a magnetic object, such as a bead, introduced into a tissue or cell—avoid the problems of damage at higher power and have “always had great promise,” says Dyche Mullins of the University of California, San Francisco. However, they have had their own difficulties. For example, while a magnetic object several microns in size can be used to push and prod the exteriors of whole cells or isolated organelles, explains Mullins, intracellular manipulations ...
