Study Of Fluorescent Nanoprobes Based On Self-Assembly Of Quantum Dots

Quantum dots (QDs) is a kind of semiconductor nanocrystals. They have uniqueoptical and electronic properties, which make them have a broad application in thefields of analytical chemistry, life science, biomedicine and material science, etc. QDscan be widely used for analytical analysis as fluorescent probes. Meanwhile, they canbe self-assembled into various functional nanostructures as building block. Recently,self-assembly of QDs for sensing has attracted much interest. In this thesis，a broadrange of analytes including adenosine small molecule, thrombin protein and As(III)ion had been detected simply and sensitively based on this principle. The details aresummarized as follows:1. Detection of adenosine based on the self-assembly of “split” aptamerfunctioned QDsA sensitive adenosine detection method has been developed based on “split”aptamer mediated self-assembly of QDs, which accompanied by fluorescentself-quenching. The adenosine aptamer was split into two pieces of ssDNA (ABA1and ABA2) and then attached to different thioglycolic acid capped CdTe QDs formingABA1-QDs and ABA2-QDs respectively. This sensing system composed three parts,QDs as building block,“split” aptamer as recognition element, and adenosine asdetecting object. Results showed that adenosine “split” aptamer can induce QDsaggregation and then fluorescent self-quenching in the present of adenosine, and thedetection limit for adenosine was1.0nM. The strategy reported here was simple,sensitive and specific.2. Detection of thrombin based on the self-assembly of “split” aptamerfunctioned QDsA sensitive thrombin detection method has been developed based on “split”aptamer mediated self-assembly of QDs, which accompanied by fluorescentself-quenching, to verify the analysis method based on self-assembly of “split”aptamer functioned QDs is universal. The thrombin aptamer (15mer) was split intotwo pieces of ssDNA (TBA1-QDs and TBA2-QDs) and then attached to differentthioglycolic acid capped CdTe QDs forming TBA1-QDs and TBA2-QDs respectively.This sensing system composed three parts, QDs as building block,“split” aptamer asrecognition element, and thrombin as detecting object. The detection limit for thrombin was4.8pM.3. Detection of As (III) based on the self-assembly of Cys-capped CdTe/CdS QDsA sensitive As(III) ion detection method has been developed based onself-assembly of Cys-capped CdTe/CdS QDs, which accompanied by fluorescentself-quenching, to verify the analysis method based on self-assembly of QDs isuniversal. Firstly, core-shell Cys-capped CdTe/CdS QDs were prepared with shellgrowth at room temperature. Then the QDs was used for sensing of As (III) ions.Results showed the detection limit for As(III) ion was10ng/L. The method wassensitive and specific, which was promising for sensing in the complex system suchserum.