ananyo writes "Chemists have turned red blood cells into long lived sensors that could be put back into circulation to monitor the make up of patients' blood in real time. Many patients require monitoring of their blood, such as diabetics. But extracting blood is both invasive and provides only a one-off measurement. At the American Chemical Society meeting in Philadelphia, Xiaole Shao explained how her team has built sensors that may one day allow both non-invasive and long-term monitoring of crucial aspects of blood chemistry. Shao, a chemist at the University of Missouri-Columbia, and her colleagues exploited the fact that near-infrared light will penetrate skin. This means it can trigger florescent molecules that are circulating in the blood, and this florescence can be picked up by an external monitoring device. If the molecule's florescence changes in response to chemical conditions, these changes can also be detected, and you have a sensor. But florescent dyes can be toxic, and they don't last long in the body, as they are quickly filtered out. To avoid the problem, the researchers encapsulated the sensors in red blood cells. The team next plans to inject the sensors into rats."