Determination of urea in serum by a fiber-optic fluorescence biosensor.

A new fiber-optic biosensor for urea has been developed, based on immobilized urease coupled to a fluorescence ammonia sensor. The enzymatically generated ammonia diffuses through the membrane into a solution of the fluorescent pH indicator trisodium 8-hydroxypyrene-1,3,6-trisulfonate. The sensor has been successfully used for the determination of urea in serum samples, with results in good agreement with those reported by a local hospital. The proposed sensor is reversible and selective to urea. The ease of construction of the sensor tip offers the possibility of designing disposable tips for use in clinical applications.