The Application Research Of Terbium Ion Detection Based On G-quadruplex And Fluorescence Sensor

Recent years,the detection of the rare earth elements(REEs),especially terbium,has attracted significant interest because of the important roles in industrial application.Above all,terbium could be accumulated in human body from the food chain,causing serious and permanent damage to the bone marrow cells,DNA and liver,even at low concentrations.Thus,the detection of terbium is critical for the environment and human health.In this thesis,several novel sensors based on Tb3+induced G-quadruplex and terbium ion unique optical properties were designed,constructed and characterized.The prepared sensors could be used for the sensitive determination of Tb3+.There are four chapters in the thesis.The main contents are listed as follows:In chapter 1,we provided a brief overview of the advance trend on fluorescent sensor and electrochemical biosensor.Especially,knowledge on the DNA probe design based on the G-quadruplex structure.Meanwhile,the sensors for the detection of metal ion,hybridization and gene diagnosis technology were summarized.Finally,the research ideas and contents of this thesis were also summarized.In chapter 2,a novel label-free fluorescent biosensor for terbium(?)(Tb3+)was proposed based on structural conversion of G-quadruplex DNA mediated by Thioflavin T(THT)and Tb3+.The change of fluorescence intensity(?F=F0-F)showed a good linear response toward the concentration of Tb3+ over the range from 1.0 pM to 1.0 ?M with a limit of detection of 0.26 pM.This proposed biosensor was simple and fast in design and in operation with ultrahigh sensitivity and selectivity.In chapter 3,a high sensitive and specific electrochemical DNA biosensor based on G-quadruplex and long-range self-assembled DNA nanostructures was developed for the detection of terbium ion.Then the addition of two assisted probes could trigger the formation of super sandwich DNA nanostructures by long-range self-assembly,resulting in an intense electrochemical response,so as to ensure the high sensitivity of the sensor,the detection limit was as low as 0.46 fM.Tb3+ could induce DNA fold into G-quadruplex,so as to ensure the high selectivity of the sensor.In chapter 4,a simple,rapid and sensitive fluorescent sensor based on the formation of terbium complex has been developed for the determination of Tb3+.The complex was prepared where thiabendazole(TBZ)as small-molecule ligand and Tb3+ as central ion.When thiabendazole alone,weak fluorescence was observed.However,in addition of Tb3+,a dramatic enhancement of fluorescence intensity was observed.Under optimal conditions,a linear relationship was obtained between the enhanced fluorescence intensity and the concentration of Tb3+ in a range of 5×10-6 M?3×10-5 M.The sensor was used for the detection of Tb3+ in river water samples,and the result was satisfactory.