The Study Of Synthesis Of Water-soluble Core/Shell Quantum Dots And Application Of Bacteria Detection

Quantum dots,a kind of semiconductor nanocrystals,have the prominent advantages such as narrow and symmetric emission spectrum, broad excitation spectrum,long fluorescence lifetime,good dispersibility and stability,and the apparente anti-photobleaching compared to the traditionary fluorescent dye.This study is to directly synthesize quantum dots in aqueous phase and apply it for bacteria detection.Two major works were studied as follows:1.Quantum dots direct synthesis in aqueous phase.In order to overcome the problems of time consuming,harsh reaction conditions and non water-solubility of quantum dots synthesis in organic solvent phase, we synthesize quantum dots directly under non-oxygen,stirring,and using the NaHSe as precursor and mercapto- acetic acid as stabilizer.We also study the effects of pH,stabilizer and it's usage to the quantum dots fluorescent.In addition,fluorescence spectrum and TEM were used to characterize the prepared nanoparticles.These results clearly showed that this method could synthetize the good and stable fluorescence quantum dots quickly under the simple condition.2.Species-specific 16S rDNA detection of Bifidobacterium.In this work,a new FRET detection system of Bifidobacteria species-specific 16S rDNA has been established using QD—ROX FRET bioprobe,in which 525nm QD-DNA conjugate consisted of the QD with modification of carboxyl surface groups and the DNA with modification of 5'-amino groups in the presence of EDC.Both 3'-ROX modified DNA and the conjugate above could hybridize with the target DNA after forming the QD—ROX bioprobe.When the hybridization narrowed the distance between the QD and ROX into FRET effect distance required,525nm QD fluorescence intensity decreased and ROX fluorescence intensity increased.By contrast,there would be no fluorescence change of QD or ROX if the hybridization is not formed with target DNA.Whether the QD and ROX fluorescence intensities change or not,a good guaranty is provided for this rapid and simple detection system.