Here's a quick video to satisfy the two loves of everyone with a computer; science and semi-ironic chair dancing. Gold and iron oxide particles are suspended in liquid. The liquid is exposed to a magnet. We see the magnet do its work to the little tune that accompanies the video.
The science here is fairly straightforward. A bunch of iron oxide and gold particles are tossed down into a liquid. The liquid is exposed to a magnet. The particles slowly, over the course of twenty minutes, pull to the far side of the liquid, hugging close to the magnet. Gold, unlike many metals, isn't magnetic. The magnet should have no effect on it. Instead, it gets dragged along.
Scientists at the University of Washington coated both the gold particles and the iron particles with special 'smart' polymers that grab on to each other. As the iron oxide responds to the pull of the magnet, it drags the gold along with it. Even when the pipette stirs up the liquid, the particles, including the gold, head right back towards the magnet. Eventually the liquid appears entirely clear, except for the strip of metal at one end. This technique might make it possible to use magnets to filter other contaminants out of liquid. Still, I think the best part of the whole thing is grooving along to the music as you watch. Don't be too proud. Chair dance a little. It's science.