Rational Design,Preparation And Application Of Fluorescent Probes Based On Macrocyclic Polyamine

Currently,fluorescent and colorimetric chemosensors for selectively detecting metal ions,anions and neutral molecules are widely used in many fields.There is still increasing interest focusing on development of new fluorescence chemosensors targeting various substrates because of their advantages of high selectivity,sensitivity and simplicity.Meanwhile,high requirements and challenges emerged about exploiting new fluorescence chemosensors accompanied by rapid development of life science.Besides the traditional molecules and ions recognition,todays research is go deep into the monitoring analysis and regulate of life system microenvironment(e.g.acidity and viscosity).Small-molecule fluorescent probes as typical fluorescence chemosensors possess features of structure simplicity,selectively and sensitive to target molecules,and well biological compatibility.More recently,visible or near-infrared light excited small-molecule fluorescent probes attract more and more attentions due to ultraviolet light probably cause damage to biological specimen and the background interference.As an ideal receptor for metal ion,macrocyclic polyamines have abundant N-donor and annular cavity of variable size.Subsequently the metal macrocyclic polyamine complex could recognize anions or biomolecules.According to these discussion,fluorophores or dyes linked to N atoms of polyamine via a spacer can developed small-molecule fluorescent probes based on macrocyclic polyamine.The dissertation describes the design,synthesis of fluorescent sensors for various ions and molecules based on pyridine contained tetraazamacrocycle and ethyl bridged bis(1,4,7-triazacyclononane).L1,L2 and L3 employed NBD or anthracene as fluorophore,respectively.The performance of these probes has been determined by fluorometric titration.Furthermore,the particular applications such as cell imaging and enzyme activity monitoring have also been thoroughly investigated and discussed.The details of the dissertation consist of the following content:(1)A tetraazamacrocycle fluorescent sensor(L1)with an anthracene pendant arm has been designed and prepared,which can be utilized for selective sensing of Zn2+in aqueous solution at physiological pH.The enhancement of fluorescence is 14 by addition of 1 equiv Zn2+ based on photoinduced electron transfer mechanism.The LOD towards Zn2+is 1.1 ?M.The association constant 1.96 × 105 M-1 has been determined by fluorometric titration.Moreover,L1-Zn2+ complex,which showed selectivity toward PPi by quenching the fluorescence(turn-"OFF"),was used to detect pyrophosphate ions released from polymerase chain reaction(PCR).Furthermore,L1-Zn2+ was also used to set up real-time fluorescence assays for monitoring the enzyme activities of inorganic PPase,adenosine triphosphate sulfurylase and alkaline phosphatase employing PPi as the substrate.Besides,our assay could also be used to estimate the inhibitory effects of ALP and ATPS inhibitors.Na3VO4 and KClO3 are well-known inhibitors for ALP and ATPS,respectively.The IC50 values of Na3VO4 toward ALP and KClO3 toward ATPS were calculated to be 16.5 ?M and 844?M.(2)A pyridine contained tetraazamacrocycle fluorescent sensor(L2)with a NBD as fluorophore has been designed and prepared,which can recognize Cu2+ based on intramolecular charge transfer(ICT)in near physiological condition.Compared to L1,excited wavelength of L2 is longer(red shift to 470 nm).The association constant between L2 and Cu2+is 2.09 × 104M-1 and LOD is 0.84 ?M.The probe can permeate cell membrane and be located in lysosomes specifically.Additionally,it can be applied for cell imaging for Cu2+in lysosomes.Combined with ICP-MS,L2 successfully applied to visualize Cu2+ as well as to monitor Cu2+ level change in the lysosomes of living cells.(3)An ethyl bridged bis(1,4,7-triazacyclononane)fluorescent sensor(L3)with two NBD pendant arms has been designed and prepared,which can rapidly recognize Hg2+(enhance factor is 80 and then decreased to 10)in near physiological condition.The LOD and associate constant of L3 towards Hg2+ are 27 nM and 4×106 M-1,respectively.L3-Hg2+can selectively bound to biothiols(RSH)such as glutathione(GSH)and cysteine(Cys).L3 can permeate cell membrane and was no significantly cytotoxic towards HeLa cells.Fluorescence imaging for Hg2+ and GSH were examined in HeLa cells using laser confocal fluorescence microscopy.Co-staining experiments with L3 and commercially available marker demonstrated L3 non-specifically located in some organelle.Furthermore,L3-Hg2+ was used for detecting of GSH in human serum and fetal bovine serum.