A homogeneous affinity fluorescence assay system for galactose monitoring

Abstract

Since the systemic venous-hepatic venous galactose gradient is normally quite large, the ability to detect different blood galactose concentrations in vivo would provide a mechanism for anatomic localization of the hepatic venous system. Furthermore, the development of a catheter assembly mounted with a galactose-sensitive biosensor would provide a technique for cannulating this organ system entirely using sensor guidance. In this report we describe a homogeneous affinity fluorescence assay system which can be contained in a dialysis hollow fiber for continuous galactose monitoring. The principle of this assay is based upon competition of freely permeable galactose for the specific binding interactions between a fluorescently labeled polysaccharide and lectin reagent pair. This competetive energy-transfer assay exhibits good sensitivity over a physiologically relevant galactose concentration range (0–2 mM), an acceptable response time (<200 s) and small dimensions, which make it potentially adaptable to conventional catheter systems for in vivo use. Such a system would greatly simplify diagnostic efforts to evaluate hepatic function in real time.