Syntheses, Characterization And Applications Of Semiconductor Nanoparticles As Fluorescence Probes

Semiconductor nanoparticles have a narrow, tunable, symmetric emission spectrum and a broad, continuous excitation spectrum. They are also photo-chemically stable and they have high fluorescence quantum yields and long fluorescence lifetime. The high selectivity and sensitivity should be acquired when the nanoparticles are used to detect the macromolecules.In this work, nano-ZnS and nano-CdS have been successfully prepared. The nano-CdS have been modified with mercaptoacetic acid, and nano-ZnS have been modified with sodium mercaptoacetic acid. The functionalized nanoparticles are water soluble ,and biocompatible. All the nanoparticles have been characterized by IR spectra, UV spectra, Fluorescence spectra and TEM images. In comparison with single organic fluorophore, the nanoparticles probes are brighter, more photostable, and do not suffer from blinking. The functionalized nano-CdS has been used as fluorescence probe in determination of Human Serum protein. Under the optimal conditions, the response is linearly proportional to HSA concentration between 0.2ug mL-1 and 3.5/ig mL-1, and the limit of detection is 0.09ug mL-1. The response is linearly proportional to Y -G concentration between 0.2ng mL-1 and 11 .Oug mL-1, and the limit of detection is 0.18ag mL-1. A fluorescence method has also been developed for rapid determination of ct-DNA with functionalized CdS as a fluorescence probe, based on the fluorescence quenching of functionalized CdS in the presence of ct-DNA. Under optimal conditions, the calibration graph is linear over the range 0.1~1.5jig mL-1for calf thymus DNA (ct-DNA). The corresponding detection limit is 0.018g mL-1, and the linear correlation coefficient is 0.9989. The assay was proved to be a simple, rapid and specific method. The recovery and relative standard deviation are very satisfactory.