| As a new kind of nano material,quantum dot has become a new research filed as it get the attention of scientific researchers at home and abroad because of its special photochemical performance.Characterized with simple preparation,convenient characterization and easy modification of surface,it has been widely applied in the detection of variable analytes.At present,although the fluorescence quantum dot is widely used in practical applications,it is always interfered by background fluorescence or scatter light of analyte matrix,and limited in practical application.But the room temperature phosphorescence?RTP?of quantum dot is able to overcome this disadvantage.Compared with fluorescent quantum dot,the room temperature phosphorescence quantum dot has longer phosphorescence lifetime,better choice and higher optical stability.Additionally,it can avoid the interference of background fluorescence or scatter light in biological fluid or other matrixes without using deoxidant and inducer,which can compensate the disadvantage and shortage of quantum dots florescent probe in detection.By taking the application of room temperature phosphorescence of MPA capped Mn-doped ZnS quantum dots asthe core,this paper applies the RTP into analytic detection of pesticide Paraquat and DNA,and further extends the scope of RTP in practical application.The main research content of this paper are as follows:?1?By taking 3-mercaptopropionic acid?MPA?as the stabilizer,the water soluble Mn doped ZnS quantum dots were synthesized at first.Then,the MPA-capped Mn-doped ZnS quantum dots were characterized by utilizing transmission electron microscope?TEM?,X ray diffraction pattern and phosphorescence spectra.Results indicate that,the Mn-doped ZnS quantum dots obtained from experiment are very uniform with diameter of 3.5nm and classic cubic structure.The strongest excitation peak and strongest emission peak of these quantum dots is occurred at 295 nm and590nm respectively.?2?A convenient and rapid detection method of pesticide“Paraquat” with high sensitivity and low detection limit is developed by using RTP nature of MPA capped Mn-doped ZnS quantum dot.The principle is given as below: taking Paraquat?PQ?as electron acceptor and combining it with quantum dot through electrostatic interaction,then quenching the room temperature phosphorescence and finally completing the detection of PQ.The linear range and detection limit of this method is 2.5-50 ?g L-1and0.769 ?gL-1respectively.This method is used for detection based on room temperature phosphorescence properties of quantum dot,which has some advantages of detection in biological fluid.?3?A simple phosphorescent compound system for DNA detection is established by utilizing Mn covered with3-mercaptopropionic?MPA?doped with ZnS quantum dots and mitoxantrone.By taking MTX as good electron acceptor,the room temperature phosphorescence of Mn-doped ZnS quantum dots was quenched through photoinduced electron transfer principle.After the addition of DNA in system,DNA and MTX was combined through static electricity and intercalation,and a more stable compound was formed as well,which enable MTX removing from the surface of Mn-doped ZnS quantum dots,achieve RTP recovery of Mn-doped ZnS quantum dots,and thus realize the trace detection of DNA.The linear scope of this system for DNA detection and the detection limit is 0.1-20 mg L-1and 0.07 mg L-1respectively.This method can effectively avoid the interference from other coexisting substances,which can be used in rapid detection of DNA content in practical biological sample. |
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