MIT Technology Review: The tissues of the heart possess a set of properties that has been hard to reproduce in the lab. The muscles are mechanically tough and electrically conductive, and they maintain a constant rhythm of motion. Researchers have been growing cardiac cells in various polymers and gels, but the resulting materials don’t have the same level of conductivity or the ability to sustain continued movement. Ali Khademhosseini, of the Harvard–MIT Division of Health Sciences and Technology in Cambridge, Massachusetts, and his colleagues believe they’ve found a solution: adding carbon nanotubes to their gels. The nanotubes are conductive, and their fibrous nature gives the material a great deal of mechanical strength and durability. Before the material can be used for any sort of medical purposes, though, the safety of the carbon nanotubes and of the material in general would have to be demonstrated. But the material could still find uses in biomechanical applications as parts of robots used to explore areas that are toxic or dangerous to humans.