Nanoparticle Magnet (IMAGE) University of Washington Caption An external magnetic field attracts the nanoparticles by their magnetic cores. When the field is turned off, the tissue relaxes and the particles return to their initial positions. Credit Xiaohu Gao, University of Washington Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.