The beads 30-nm size (with an inner 5-nm particle) provides the optimal crystal geometry to make them superparamagnetic able to be magnetized and demagnetized over and over, notes Mannix, who shares first authorship of the paper with Sanjay Kumar, MD, PhD of Childrens. (Kumar is now a faculty member in Bioengineering at the University of California at Berkeley.) To give a sense of scale, one nanometer is to a meter (about a yard) as one blueberry is to the diameter of the Earth.
The beads were made to attach to the mast-cell receptors by pre-coating them with antigens; these antigens then bound to antibodies that coated the receptors, similar to the way antibodies bind to antigens in the immune system. Our goal was to have one antigen coating each bead, so that each bead would bind to just one receptor, Mannix says.
As an accompanying News & Views article notes, scaling down the interactions to single receptors demonstrates unprecedented control at the individual protein level.
Electrical stimuli have been used to influence the activity of nerve cells, but isnt effective in cells that arent electrically excitable by nature, the researchers note. The advantage of a nanomagnetic control system is that it can be used in a broad range of cell types and provides a near-instantaneous on-off switch, unlike hormones and chemicals that can take minutes to hours to act and then may linger in the body. In addition, magnets can be portable and have low power requirements, allowing their use in the military and other mobile situations.
Ingber envisions a kind of pacemaker that would involve an injection of nanoparticles
|Contact: James Newton|
Children's Hospital Boston