The recombinant Factor C (rFC) assay is a modern, animal-free alternative for detecting bacterial endotoxins, offering comparable sensitivity and accuracy to traditional Limulus Amebocyte Lysate (LAL) tests. This assay utilizes recombinant factor C, a genetically engineered protein derived from the horseshoe crab's natural Factor C, to trigger a fluorescent signal in response to endotoxins.
Activation by Endotoxin:
Recombinant Factor C is activated upon binding to bacterial endotoxin (lipopolysaccharide, LPS).
Fluorescent Substrate Cleavage:
The activated Factor C cleaves a synthetic fluorogenic substrate, releasing a fluorescent signal.
Quantification:
The intensity of the fluorescence is directly proportional to the endotoxin concentration in the sample. Fluorescence is measured using a fluorometer, and endotoxin levels are determined using a standard curve generated with known concentrations.
Sample Preparation:
Test samples are diluted in endotoxin- free water or buffer, then mixed with the rFC reagent.
Reaction Incubation:
The mixture is incubated at a controlled temperature, allowing the reaction to occur.
Fluorescence Measurement:
The fluorescence intensity is measured at specific wavelengths corresponding to the fluorogenic substrate used.
Data Analysis:
A standard curve, generated from known endotoxin concentrations, is used to calculate the endotoxin levels in the test samples.
Animal-Free: Eliminates the need for horseshoe crabs, promoting sustainability and ethical testing practices.
High Specificity and Sensitivity: Accurately detects endotoxin levels, comparable to traditional LAL tests.
Robustness: Reduced variability compared to biological assays using lysate.
Cost-Effective: May reduce reliance on seasonal collection and processing of natural lysate.
Endotoxin detection in pharmaceutical products, biologics, medical devices, and injectable solutions.
Quality control in production facilities adhering to regulatory requirements for endotoxin limits.
The rFC assay is increasingly adopted in industries prioritizing sustainability and compliance with animal welfare guidelines, while maintaining rigorous standards for endotoxin detection.