A team of MIT researchers have developed nanoparticle sensors that could eventually be used to monitor tumors or other diseases, as well as act as a tool to diagnose illnesses. These nanoparticles are made of polymer chains that can bind to the sensors a doctor needs. For instance, in the scientists’ tests, they used an MRI contrast agent called nitroxide along with Cy5.5, which glows when it encounters vitamin C, as sensors.