Electrochemical sensing strategies for the detection of endotoxin: a review

Endotoxin, also referred to as lipopolysaccharide (LPS), is a membrane constituent of gram-negative bacteria, which can initiate immune responses. However, excessive inflammatory responses to endotoxin may lead to life-threatening conditions like irreversible septic shock and even death. Therefore, sensitive detection systems to trace a small amount of endotoxin in foodstuff and medical supplies are urgently needed for health concern. So far, there is an ongoing and extensive research for the development of various endotoxin sensors. Limulus amebocyte lysate (LAL) test is a widespread standard assay. However, LAL test may suffer defects of inadequate stability, high cost and inconvenience. Recently, many advanced techniques are introduced in the fabrication of endotoxin sensors to overcome these defects, such as fluorescence, chemiluminescence, electrophoresis, as well as electrochemical techniques. Among them, electrochemical systems are proved to be effective alternative detection systems with the advantages of low cost, easy operation, rapid analysis, high sensitivity and selectivity. This review summarises recent advances of the electrochemical strategies for the detection of endotoxin, which are designed based on different recognition mechanisms and signal transformations.