A ratiometric fluorescent probe for alkaline phosphatase with high sensitivity

Alkaline phosphatase (ALP) is one of essential biomarkers in mammalian tissue. Here we report a ratiometric probe for ALP, which is rationally designed and synthesized by employing ESIPT fluorophore N-(3-(benzo[d]thiazol-2-yl)-4-hydroxyphenyl)benzamide (BTHPB). The enzymatic dephosphorylation converts the probe to BTHPB, which exhibits a large spectral red-shift (120 nm), allowing extremely high sensitivity of ALP sensing at 0.004 mU/mL. The probe also shows excellent biocompatibility and has been applied for monitoring the endogenic ALP in living cells. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.