Fluorometric Nanoscale Analysis of Bilirubin and Biliverdin in Human Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a valuable source for the quantification of soluble, brain-specific biomarkers supporting the diagnosis of some neurological disorders, infectious diseases, and suspected subarachnoid hemorrhage. Given the increasing need to expand the basic knowledge of brain pathophysiology for disease biomarker discovery, we set the goal to quantify bilirubin and biliverdin in human CSF. Their concentrations are expected to reflect the level of brain heme catabolism, a key pathway involved in the biological response to oxidative stress. Here, we present the results of the CSF analysis by a specific and sensitive fluorometric method using the recombinant fusion protein HELP-UnaG (HUG). The concentrations of bilirubin and biliverdin in 50 human CSF samples were in the ranges of 14-340 and 0-66 nM, respectively. This assay can be easily implemented in small-scale laboratories and neurological units for the routine analysis of clinical CSF samples.