From Popular Science: "Giving cardiac patients a heart of gold nanowires could ensure engineered tissue works like it should, pulsing in unison to make the heart beat. First growing nanowires and then growing heart cells, [engineers] say their new muscle-machine blended heart patch improves on existing cardiac patches, which have trouble reaching a consistent level of conductivity. ... Electrical signals shared among calcium ions dictate when cardiomyocytes contract, making the heart beat. But tissue scaffolds are often made with materials like polylactic acid or alginate, which act as insulators, so the signals are blocked. This makes it difficult to get all the cells in a piece of tissue to coordinate their signals and beat in time, which in turn makes it difficult to build a very big or very effective heart patch. The [rsearch team] gets around this problem by integrating gold, an excellent conductor. They mixed alginate, a gummy substance often used in tissue scaffolds, and grew gold nanowires throughout it. Then they seeded the alginate with cardiomyoctes from rat embryos, and monitored calcium levels to gauge their electrical conductivity. Compared to a typical scaffold system, the gold nanowire cells' conductivity improved by three orders of magnitude."