Aggregate 'Clumps' (image) The Optical Society Caption The addition of target viral DNA causes the nanoparticles to form aggregate "clumps," which leads to a change in their color. Credit Credit: Matthew Mancuso. Usage Restrictions None 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.