DNA Functionalized Fluorescent Quantum Dots For The Study Of Detection Of HAV

Semiconductor nanocrystals(quantum dots)are a new class of zero dimensional materials with a typical size range of 1-100 nm.When the size of the semiconductor crystal is smaller than the exciton Bohr radius,the charge carrier is confined in space and exhibits obvious quantum effect.With the decrease of the size,the characteristics of the quantization are more obvious,and the energy is higher and higher.As a result,the color of QDs can be adjusted in the UV,visible,and near infrared spectral range by simply changing the size of their dimensions.Compared with conventional organic dyes,QDs have unique optical and chemical properties,including high quantum yields,good photostability,broad absorption peaks,narrow and tunable emission peaks.These attractive properties make quantum dots an ideal choice for fluorescent labeling.This paper is to synthesize CdTe/CdS core-shell quantum dots by aqueous reflux method.DNA functionalized CdTe/CdS core-shell quantum dots were synthesized by chemical bonding.Using QDs-DNA as a f luorescent probe detected HAV virus,mainly in the following three aspects of work:1.The CdTe quantum dots were synthesized in aqueous solution by using sodium borohydride and K2TeO3 as precursor and then adding Cd(CH3COO)2·2H2O solution to acetic acid as stabilizer.Then,Using CdTe quantum dots as matrix,Water soluble CdTe /CdS core-shell quantum dots were synthesized by adding CdCl2·5H2O,TGA and Na2S·9H2O into the water phase under the condition of argon.CdTe /CdS core-shell quantum dots were purified and the CdTe /CdS core-shell quantum dots were characterized by fluorescence spectroscopy and transmission electron microscopy.The experimental results show that the preparation method is simple and fast and finally the water-soluble CdTe /CdS core-shell quantum dots are obtained with good fluorescence stability and excellent optical properties.The particle size is about 4-5 nm.2.DNA functionalized CdTe /CdS core shell quantum dots were synthesized on the basis of DNA of amino and CdTe core shell quantum dots.DNA functionalized CdTe /CdS core-shell quantum dots are cleaned and purified.And then DNA functionalized CdTe / CdS core-shell quantum dots were characterized by ultraviolet spectrum,fluorescence spectrum and transmission electron microscopy.The ratio of DNA and CdTe /CdS core-shell quantum dots is optimized.The experimental results show that the DNA functionalized CdTe /CdS core-shell quantum dots have good fluorescence stability and excellent optical properties and the particle size is about 11-12 nm.The optimal ratio of QDs and DNA is 1:30.3.A new,fast,sensitive and specific method for the detection of HAV virus was established by using the functionalized CdTe /CdS core shell quantum dots(QDs)as an energy donor and dye(Cy5)as energy acceptor.In the detection system,when DNA functionalized CdTe /CdS core-shell quantum dots,Cy5 dye DAN and target DNA hybrid pairing,the fluorescence intensity of DNA functionalized CdTe /CdS core-shell quantum dot weakened and the fluorescence intensity of Cy5 enhanced.When the interference DNA is added,the fluorescence intensity of the quantum dots will not increase and the fluorescence intensity of the Cy5 dye will not weaken.The experimental results show that the fluorescence intensity of the Cy5 can be used for quantitative detection of HAV,and the detection method has high specificity and sensitivity.The effects of hybridization time,interference DNA and quantitative detection of HAV were discussed.In this method,the concentration of target DNA has a good linear relationship with t fluorescence intensity of Cy5.The linear range is 0-100 nmol/L and the detection limit is 3 nmol/L.