Design Of Novel FRET Platforms And Their Research And Application In Biosensing

Fluorescence is the output signal of fluorescent chemical sensor.The fluorescent chemical sensor was widely used in analysis,analytical science,life science and other fields due to its good selectivity,high sensitivity and simple means of detection.Our work is focused on design of fluorescent sensor based on fluorescence resonance energy transfer(FRET),and applied to the detection of biomolecules.The main research contents are as follows:(1)A sensitive fluorescence turn-on biosensing platform for thrombin assay has been developed based on the FRET between iridium(III)complex and cationic conjugated polymers(CCP).The CCP-Ir(III)complex assay is based on electrostatic interaction and ?-? stacking interaction between CCP and Ir(III)complex,which leads to the occurrence of FRET.The negatively charged thrombin aptamer increases the distance between the CCP and Ir(III)complex,and the FRET of the system was affected.But afterwards the reappearance of FRET phenomenon was confirmed by the special binding interaction between aptamer and thrombin,thus a “turn-on” fluorescent sensor was constructed to detect thrombin.The sensor has the advantages of good specificity,high sensitivity,accurate and reliable result,low cost,high speed and simple process.Moreover,the strategy may allow our platform to provide similar sensitivity toward different targets in an aptamer-structureindependent manner.(2)Single strand binding protein(SSB)is a key protein in all living cells,which can interact with a large number of proteins,leading to other proteins play a role in DNA replication,repair,and so on.Two kinds of label-free fluorescence biosensing platforms for DNA and protein assay have been developed based on electrostatic interaction and ?-? stacking interaction between CCP and Ir(III)complex,which can be used for the quantitative analysis of SSB.The first method is based on the role of ssDNA and SSB,and the second method based on the role of hairpin DNA and SSB.In addition,the first method can be used to identify the length of ssDNA.(3)Exonuclease I(Exo I)in many biological process plays an important role,such as: DNA replication,recombination and repair etc.One of the most important functions is to manintain the probability of mutation in the body,thereby maintaining the stability of genetic information.A “turn-on” fluorescent sensor was constructed to detect exonuclease I activity based on FRET between CCP and Ir(III)complex.Moreover,our method is robust enough to be applied to detect the amount Exo I activity in human urine or serum.(4)Ascorbic acid(AA),present in fruits and vegetables,is an important micronutrient that is essential for humans and animals.The lack of AA can lead to scurvy,but too much AA intake may lead to urethral calculi,diarrhea,stomach cramps and other diseases.We constructed a new fluorescence resonance energy transfer system between CCP and quantum dot(QDs),in which CCP as a donor,and QDs as a receptor.The introduction of AA displayed an etching effect on the QDs,thus the fluorescence intensity of QDs decreased,contrarily,the fluorescence intensity of CCP can be enhanced.