Nanosensors (image) Johns Hopkins Medicine Caption Nanosensors (green spheres) are composed of fat and L-arginine molecules, as well as separate indicator molecules that give off MRI-detectable and light signals when cells are alive. Nanosensors are enclosed in a hydrogel membrane along with liver cells (pink). Nutrients and other relatively small molecules (red) are able to travel across the hydrogel membrane to and from the bloodstream. Credit Sayo Studios Usage Restrictions Must be credited to Sayo Studios 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.