Study On Fluorescence Analytical Methods Based On Quantum Dot Probe And Enzyme Auxiliary Signal Amplification Technique

In recent decades,the application of semiconductor nanomaterials in biosensing analysis field has attracted widespread attention.Owing to the photoelectric properties afforded by the small-size effect of nanomaterials,high quantum yield,relatively narrow and tunable emission wavelength,quantum dots as nano biological probes have been applied in various fields.Fluorescence?FL?analysis method has remarkable features such as simplicity,rapidity,high sensitivity and easy controllability,and has been extensively used for the detection of a wide variety of biomolecules.In this paper,we mainly studied the preparation of many quantum dots,fabrication of quantum dots bioprobe,development of the FL biosensor based on signal amplification technology,and achieved highly sensitive detection of RNA,carcinoembryonic antigen,T4 PNK kinase and other tumor markers.The three parts of this thesis are studied as follows.1.In this study,a novel strategy for fluorescence detection of dual target miRNAs?miRNA-141 and mi RNA-21?based on two distinguishable CdSe/ZnS and CdTe quantum dot?QD?probes by target recycling amplification strategy was reported.The hairpin?HP?DNA was firstly linked to the magnetic bead@Au?MB@Au?complex,then the present target mi RNAs hybridized with HP,which initiated the Exonuclease III-aided target recycling process,leading to the generation of numerous intermediate DNA sequences?s1?on MB@Au.Subsequently,a large number of QDs fluorescence probes were introduced to hybridize with s1,which will further trigger the scission with addition of Nb.BbvCI.Much amplified fluorescence signal of QDs was detected through convenient magnetic separation,which has a quantitative relation with the target miRNAs.2.A new water soluble Mn:ZnCdS@ZnS core-shell quantum dot with excellent fluorescence property was synthesized,and used to fabricate a fluorescence signal probe.By using the amino modified SiO₂ microspheres as carrier,a novel fluorescence biosensor was developed for detection of carcinoembryonic antigen?CEA?based on the Mn:ZnCdS@ZnS QDs labeled signal probe by enzyme-aided target recycle amplification technique.At the same time,the DNA S1–DNA3 double chain generated by polymerization further reacted in the presence of ATP,T4 PNK and ? Exo,and achieved detection of T4 PNK kinase activity by using HCR amplification technology and CdTe QDs-DNA signal probe.Therefore,the fluorescence biosensing method was used for sensitive detection of both CEA and T4 PNK.3.We have prepared a novel DNA nanocage for sensitive detection of hOGG1 based on CdTe signal probe and enzyme-aided amplification technique,and further finished fluorescence labeling and targeted drug delivery to the MCF cell.Firstly,DNA HP1?containing 8-oxo-dG?was decomposed into DNA fragment 1 and 2 in the presence of hOGG1.Then lots of trriger DNA?containg nucleolin adapter fragment?were produced after adding HP2 and Exonuclease.Fluorescence QDs were labeled to the DNA nanocage for sensitive detection of hOGG1 activity.When anti-cancer drug doxorubicin?Dox?was embedded into the DNA nanocage,the fluorescence is "OFF".When the DNA nanocage was into MCF cells by combination of aptamer with nucleolin,the Dox is free and fluorescence is "ON".Therefore,both the fluorescence imaging and targeted drug therapy of cancer cells were achieved.