Cell-Based Electrochemical Assay for Endotoxin Using a Secreted Alkaline Phosphatase Reporter System

Abstract

We developed a cell-based assay device for the detection of endotoxin, the potentially toxic compound that induces septic shock. Genetically-engineered cells that secrete alkaline phosphatase (SEAP) on exposure to endotoxin were cultured in an electrochemical cell device in medium containing p-aminophenyl phosphate and various concentrations of endotoxin. After 24 hr incubation, p-aminophenol (pAP), generated by SEAP-catalyzed hydrolysis, was detected by amperometry at +0.35 V. The amperometric response increased with the concentration of endotoxin in the range of 0.01–1 ng/ml.