That's exactly what it is, actually! See-

[Varian reaches up to hold the staff a little closer to the top so he can bring the vials closer into view, tapping them gently with his finger.]

It's because of the different compounds I put in here! Oxygen combines with calcium, adenosine triphosphate and luciferin in the presence of luciferase, which is a kind of a bioluminescent enzyme-

So, a chemical reaction between those elements makes them glow, basically!