Near-infrared luminescence quenching method for the detection of phenolic compounds using N-acetyl-L-cystein-protected gold nanoparticles-tyrosinase hybrid material

A rapid and simple near-infrared (NIR) luminescence quenching method for the detection of phenolic compounds based on combining the unique property of N-acetyl-L-cysteine-protected gold nanoparticles (NAC-AuNPs) and tyrosinase (Tyr) enzymatic reactions is described. This method relies on the luminescence quenching of NAC-AuNPs-tyrosinase (NAC-AuNPs-Tyr) hybrid material by phenolic compounds. The quinone intermediates produced from enzymatic catalytic oxidation of phenolic compounds were believed to play a major role in the luminescence quenching. Dynamic quenching mechanism was confirmed by using time-resolved luminescence spectroscopy. Optimization of the experimental parameters including the concentration of NAC-AuNPs-Tyr (20 mu g/mL), excitation wavelength (450 nm), pH (6.0), and temperature (20 degrees C) has been determined. A linear range 0.5 mu M to 1.0 mM and a detection limit 0.1 mu M of catechol were obtained under optimal conditions. The sensitivity of different phenolic compounds was compared and follows the trend: catechol > p-cresol > phenol. The proposed NIR luminescence quenching method exhibits high sensitivity, good repeatability, and long-term stability, demonstrating potential for further development to NIR luminescence phenol biosensors. (C) 2009 Elsevier B.V. All rights reserved.