PNPG (4-Nitrophenyl β-D-glucopyranoside) is a chromogenic substrate for β-D-glucosidase that, upon enzymatic cleavage, yields a yellow solution.

9-Methylacridine is an environmentally sensitive fluorescent probe that can couple with carboxylic acid molecules. Under ultraviolet light above 360 nm, it decomposes and releases the coupled carboxylic acid, exhibiting excellent cellular permeability and imaging capabilities.

Coelenterazine hcp is a synthetic bioluminescent luciferin that displays an emission maximum of 445 nm.1It has been used as a calcium indicator and substrate to quantifyRenillaluciferase activity.1,2,3 1.Sabnis, R.W.Handbook of biological dyes and stains: Synthesis and industrial applications(2010) 2.Shimomura, O., Kishi, Y., and Inouye, S.The relative rate of aequorin regeneration from apoaequorin and coelenterazine analoguesBiochemistry Journal296(Pt 3)549-551(1993) 3.Pichler, A., Prior, J.L., and Piwnica-Worms, D.Imaging reversal of multidrug resistance in living mice with bioluminescence: MDR1 P-glycoprotein transports coelenterazineProc. Natl. Acad. Sci. USA.101(6)1702-1707(2004)