A synthetic luciferin improves bioluminescence imaging in live mice.

Firefly luciferase is the most widely used optical reporter for noninvasive bioluminescence imaging (BLI) in rodents. BLI relies on the ability of the injected luciferase substrate D-luciferin to access luciferase-expressing cells and tissues within the animal. Here we show that injection of mice with a synthetic luciferin, CycLuc1, improves BLI with existing luciferase reporters and enables imaging in the brain that could not be achieved with D-luciferin.