What type of reagent is used for endotoxin detection in the LAL assay?

This is the traditional and classic type of LAL reagent. When endotoxin interacts with the reagent, it activates a series of coagulation factors in the lysate, leading to the formation of an insoluble gel clot. The presence of endotoxin is determined by observing whether a gel clot forms, and semi-quantitative results can be obtained through serial dilution of samples. It is widely used for qualitative or semi-quantitative endotoxin detection in pharmaceuticals, medical devices, and biological products.

This reagent relies on the turbidity change caused by the formation of coagulin polymers during the endotoxin-coagulation reaction. The turbidity of the reaction system is proportional to the endotoxin concentration within a certain range. It is suitable for automated quantitative detection, and can be paired with microplate readers or dedicated turbidity analyzers for high-throughput testing.

This type of reagent is modified by adding a synthetic chromogenic substrate (usually a peptide with a chromophore group). Endotoxin activates the coagulation enzyme in the lysate, which cleaves the chromogenic substrate to release a colored product. The absorbance of the colored product is measured by a microplate reader, and the endotoxin concentration is calculated based on a standard curve. It features high sensitivity, strong specificity, and is ideal for precise quantitative detection of trace endotoxins.