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Uric acid detection
17 October 2006
Luminescent lanthanide complexes can be used to rapidly detect uric acid levels in urine and blood, say UK scientists.
The level of uric acid in biological fluids is a balance between its synthesis in the liver and excretion in urine. It is an important diagnostic marker in medicine - high levels of uric acid are associated with kidney damage and gout, a condition where uric acid precipitates in the joints leading to pain and inflammation. Low levels may occur in people with AIDS or cancer.
David Parker and colleagues at Durham University have exploited the luminescence of a mixture of two lanthanide complexes to determine uric acid levels. The method accurately detects the target molecule in diluted urine and serum samples and is faster than the current route. At present, enzymes are used, but other compounds interfere with the measurement and an incubation period of at least 30 minutes is required.
The sensing mixture is made up of two different macrocyclic complexes - one with a terbium centre that emits green light, and the other with a europium centre that emits red light. The sensor measures the ratio of the light intensity emitted from the two luminescent lanthanide molecules on interaction with the urate anion, the conjugate base of uric acid. 'The ratiometric method internally compensates for non-specific effects that may influence emission from each individual complex,' explained Parker.
In the short term, Parker envisages that the method could be used for routine clinical analysis as the equipment required is commonly found in a modern analytical laboratory.
Thorri Gunnlaugsson, an expert in lanthanide chemistry for sensing applications at Trinity College Dublin, Ireland, welcomed the idea. 'This method is fast and more reliable than the bioassay used today,' he said. 'The sensor could be used in the same way fluorescent sensors are used for critical care analysis in hospitals and ambulances.'
ReferencesR A Poole, F Kielar, S L Richardson, P A Stenson, D Parker, Chem. Commun., 2006, 4084