Key points from article :
Nano-scale bead can be positioned inside a human cell in three dimensions.
Previously, manipulation of sub-cellular structures required freeze-drying the cells.
New system uses six magnetic coils placed in different planes around a microscope coverslip.
Cells easily take up the 700 nm magnetic iron bead inside their membranes.
Can control the position to within a couple of hundred nanometres.
Robotic system has been used to study early-stage and later-stage bladder cancer cells.
Stiffness of nucleus may help identify stage of cancer.
In future, swarms of these nanobots could destroy resistant tumours via mechanical ablation.
The study was published in Science Robotics.
