Multiple choice Which among the following has capacity to bind with the free intracellular calcium? Indo-1 Fura-2 Fluo-3 Fluo-4 JUNQ Reveal answer Fill a bubble to check yourself B Correct answer Explanation Fura-2 is a ratiometric fluorescent dye which binds to free intracellular calcium. It was the first widely used dye for calcium imaging, and remains very popular.