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A Novel Fiber Optic Biosensor for the Determination of Adrenaline Based on Immobilized Laccase Catalysis

Abstract A novel fiber optic biosensor for the determination of adrenaline based on immobilized laccase catalysis and fluorescence quenching was designed and fabricated. The immobilized laccase formed by the immobilization of laccase on the CuTAPc-Fe3O4 nanoparticles composite were used to catalyze the oxidation of adrenaline and the fluorescent oxygen-sensing membrane was used to detect the consumption of oxygen. The effects of pH and temperature on laccase activity using adrenaline as the substrate were studied. The optimal pH and temperature for the activity of immobilized laccase are 5.0 and 55°C, respectively. The immobilized laccase has good thermal, storage and operation stability. The lock-in technology was used to detect the change of the life time of the oxygen-sensing membrane. By using ABTS as the electron mediator, the biosensor showed a response time of 30 sec. The biosensor has good performance in the adrenaline concentration ranges of 2.0 × 10−7 to 9.0 × 10−7 mol/l and 1.0 × 10−8 to 9.0 × 10−8 mol/l, and it also shows good stability.