Alkaline phosphatase is an enzyme widely distributed in human liver, bone, intestine, kidney and placenta and other tissues discharged from the gallbladder through the liver. It is a commonly used biomarker in immunodiagnostic reagents and an important therapeutic target. The detection of alkaline phosphatase can be used for the diagnosis of liver dysfunction, osteoporosis and diabetes. Common alkaline phosphatase substrates include PNPP and BCIP / Nitrotetrazolium blue chloride combinations.

PNPP is widely used as a substrate for ELisa detection of alkaline phosphatase. The principle is that the colorless p-nitrophenyl phosphate disodium (PNPP) in alkaline solution can be catalyzed by alkaline phosphatase to decompose the phosphate acyl group. The basic phenol is transformed into a quinoid structure in an alkaline solution, showing a deep yellow color, that is a water-soluble yellow product. Alkaline phosphatase can be detected by detecting the rate of increase in absorbance at a wavelength of 405 nm.

PNPP is also used for pesticide residue detection, ancient cultural relics collagen detection, etc. It is also an important chemical intermediate in the field of medicine and pesticide synthesis.

BCIP /Nitrotetrazolium Blue Chloride(NBT) is a luminescent substrate combination of alkaline phosphatase. The principle is that under the catalysis of alkaline phosphatase, BCIP will be hydrolyzed to produce a highly reactive product, which will react with NBT to form an insoluble dark blue. The color-to-blue-purple product has a strong characteristic and is easy to capture and analyze to achieve the labeling effect.

BCIP is not only used as an alkaline phosphatase chemical tissue substrate in biochemical research and medicine, but also in food safety testing.

NBT is the most common application for detecting alkaline phosphatase substrates in immunoblotting experiments. In addition, nitrotetrazolium blue chloride (NBT) is also used as a substrate for dehydrogenase and other peroxidases for the determination of glucose-6-phosphate dehydrogenase, lactate dehydrogenase, superoxide dismutase, etc. .