A quartz crystal microbalance sensor for endotoxin assay by monitoring limulus amebocyte lysate protease reaction

•A QCM sensor for endotoxin assay based on limulus amebocyte lysate is constructed.•The method has a detection limit of 0.005 EU mL−1.•Fibrinogen layer is utilized to enhance signal intensity and shorten reaction time.•A simple regeneration procedure is demonstrated to be available.

Endotoxin is able to trigger strong innate immune responses by interacting with specific receptors on immune cells. Therefore, accurate and rapid detection of endotoxin is of primary importance. In this study, endotoxin induced viscosity variation of limulus amebocyte lysate (LAL) reagent is monitored by a quartz crystal microbalance (QCM) sensor with enhanced signal. Based on the analysis of the relationship between endotoxin concentration and QCM frequency shift with time, an effective sensing strategy is developed for endotoxin assay, which shows excellent sensitivity and specificity in the linear detection range from 0.005 to 10 EU mL−1. Moreover, this QCM sensor could be reused after a simple regeneration procedure. Therefore, it has potential practical utility for endotoxin determination in various applications.

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