ZnS nanoparticles for high-sensitive fluorescent detection of pyridine compounds

Water-soluble ZnS nanoparticles (NPs) capped with alpha-thioglycerol (TGO) have been synthesized through a chemical precipitation method. The nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-Vis absorption spectroscopy, fluorescence spectroscopy, and fluorescence decay spectroscopy. Results showed that the TGO-capped ZnS NPs exhibited the cubic zinc blende structure, and the average size was found to be similar to 2.94 nm. Compared with the bulk ZnS, the band-gap energy of the nanoparticles (4.40 eV) rose significantly due to the strong quantum confinement. The TGO-capped ZnS NPs showed a characteristic blue luminescence corresponding to two emission peaks at 419 nm and 460 nm associated with the defect states of the nanoparticles. Such functionalized nanoparticles can be used as fluorescent sensor for the determination of pyridine compounds because they quenched the fluorescence of the nanoparticles effectively. The detection limit was 6.76 x 10(-5) M for pyridine. The quenching mechanism was studied in detail, and the results demonstrated the existence of dynamic quenching processes. The proposed sensing method is not only sensitive, simple, fast and low cost, but also meaningful for practical applications. (C) 2013 Elsevier B.V. All rights reserved.