Detecting endotoxin in dialysis fluid using bioluminescence

Abstract

 We released the Bioluminescence Endotoxin Analyzer (Luminutes-ET) for hemodialysis facilities in April 2017, which uses a new detection method combining LAL reaction and bioluminescence. The bioluminescence method has superior Signal/Noise ratio, allowing fast and highly sensitive measurements of up to 0.0003EU/mL in under 20 minutes.

 This detection method applies the mutant firefly luciferase discovered by Kuroda laboratory at Hiroshima University which is 10 times higher in luminescence intensity compared to the wild-type. We designed the analyzer and reagent kit to significantly reduce measurement errors and lyophilized the reagent for long-term stability.

 The luciferase developed by Kuroda laboratory was not suitable for detecting endotoxin in dialysis fluid as its luminescence reaction was affected by the Na^＋ in dialysate solutions. We improved on this luciferase to prevent the effect of Na^＋ on its reaction. As a result, endotoxin detection in deionized water, i.e. dialysis water, and dialysis fluid now uses the same calibration curve.

 Endotoxin measurement using this bioluminescence method was evaluated ; its accuracy and measurement validated at six hemodialysis facilities based on the common guidelines set forth by Japanese Society for Hemodiafiltration. The validity of its calibration curve, blank tests, reaction interfering factor tests, detection limits, and quantitation limit of dialysate measurement were assessed. In conclusion, the bioluminescence method’s fast and highly sensitive measurements were verified, and was confirmed that it is fit for biological contamination control in dialysis fluid.