Researchers at the Niels Bohr Institute, University of Copenhagen, Denmark, have shown that nanoscale gold particles are good for transferring heat and could be a promising tool for creating localized heating in a living cell. The researchers were able to measure the temperature of the gold nanoparticles with extreme precision, and examine their ability to melt the liquid membranes surrounding cells, paving the way for dissolving sick cells. The technology uses optical tweezers, which use an extremely focused laser light that can trap and hold gold particles, and by turning the light up or down, control the heat. The gold nanoparticles are able to reach several hundred degrees at a light intensity of less than one watt. The heat source is well defined, and able to melt the lipids in a cell membrane – killing that cell, but only that cell. Anders Kyrsting, a PhD student in biophysics, who conducted the research along with his colleagues from the Optical Tweezers group, says “[T]he heat decreases so rapidly that at just a radius of a gold particle from the surface, the heat is half the temperature than it is at the surface. That is to say, that a typical cell length away from the particle the heat will have decreased so much that it is harmless.”