A novel near-infrared fluorescence quenching method has been developed for the determination of hydrogen peroxide based on N-acetyl-L-cysteine-capped gold nanoparticles (NAC-AuNPs) as a fluorescence probe. The prepared gold nanoparticles with the size of about 1.91 nm exhibited strong near-infrared fluorescence emission at 693 nm with excitation wavelength at 450 nm in aqueous solution. The fluorescence intensity of NAC-AuNPs was quenched dramatically by adding hydrogen peroxide. Therefore, it could be used to detect hydrogen peroxide based on the fluorescence quenching intensity was linear with the concentration of hydrogen peroxide. Under the optimal experimental conditions, the linear range and detection limit were 1.0×10-6 –3.0×10-2 mol/L and 1.0×10-7 mol/L, respectively. The possible quenching mechanism was investigated by time-resolved fluorescence spectroscopy. The proposed method was simple, sensitive and showed good repeatability and stability.
