Application Research Of Lanthanide Cerium Coordination Polymer In Heavy Metal Ions And Small Biomolecules Monitoring

Rare earth elements possess excellent optical properties such as high fluorescence quantum yield,long fluorescence life,large stokes shift,narrow emission spectrum,etc.,which are widely used.The rare earth coordination polymer is constructed with center of rare earth ions and skeleton of organic ligand.It not only retained the unique luminescence properties of rare earth elements,but also added a porous,size-tunable and other excellent properties.However,most ligands used for rare earth coordination polymers are generally poorly biocompatible organic ligands.They are not conducive to the detection of actual biological samples,thereby limiting their application in biological analysis.On the other hand,in the field of environmental monitoring,the actual sample composition is complex.Thus,the stability and selectivity of rare earth coordination polymers are particularly important.Therefore,the development of sensitive,stable,and specific rare earth coordination polymers probes is of great significance.It is well known that choosing the right ligand is crucial for the synthesis of coordination polymers.Due to the good biocompatibility of nucleotides,it have made good progress in the field of biology as a ligand.On the other hand,since the good affinity of Ln³⁺for carboxyl groups,the terephthalic acid derivatives have been used as bridging ligands for lanthanide coordination polymers,and the preparation method is mature.We can use the functionalization of ligands to improve the recognition ability of the synthesized coordination polymer to the target analytes so as to achieve the purpose of specific detection.Finally,the establishment of an internal standard can reduce the interference of many difficult control factors,and it is beneficial to the stability and sensitivity of the detection.Compared with traditional fluorescent dyes,nano-fluorescent quantum dots have excellent photophysical properties and are easy to functionalize.They have the advantages of controllable emission wavelength,strong fluorescence intensity,stability,commercialization,and low cost,and are a good choice for internal reference.This article is devoted to the development of rare-earth coordination polymers fluorescent nano-probes with excellent performance for the construction of sensitive,stable,and selective fluorescent small biomolecules and environmental heavy metal ions sensors.It has opened up the research of rare earth coordination polymers field.In this thesis,the main research based on lanthanide coordination polymer as follow sections.1.We generalize the construction,designing,developing and application of lanthanide coordinate polymer.As an excellent fluorescence probe,lanthanide coordinate polymer have been applicated in biological analysis,environment detection and drug delivery.The concept of it is derived from coordinate polymer,which combine the outstanding optic characteric of lanthanide ions,and then applicating in the detection of ions,biological analysis and drug delivery.Due to the flexible choice of ligand and centra ions,vast lanthanide coordinate polymers have been developed and utilized.2.A dual-emission fluorescence probe,lanthanide cerium coordination polymers nanoparticles,has been developed to detect H₂O₂.The dual-emission rare earth coordination polymers?Ce-QDs-CPNs?was synthesized by the coordination of rare earth ions,carboxyl Cd Se QDs and ATP molecule.The prepared Ce-QDs-CPNs exhibits the dual-emissions peaked at 369 and 525 nm,respectively.In the presence of H₂O₂,the dual-emission nanoparticles Ce?III?-QDs-CPNs would be oxidated to Ce?IV?-QDs-CPNs,leading to the quench of the fluorescence(I₃₆₉)of Ce?III?,while the green fluorescence of QDs(I₅₂₅)is almost unchanged,which can act as an internal reference to efficiently avoid the environmental interferences.Base on this,a novel and simple ratiometric fluorescent assay for the sensitive detection of hydrogen peroxide?H₂O₂?has been developed.Under the optimal conditions,a good linear relationship between the fluorescence intensity ratio(I₃₆₉/I₅₂₅)of Ce-QDs-CPNs and the concentration of H₂O₂ is obtained within the wide concentration range from 1 nM to 30?M,with a low detection limit of 0.1 nM.In addition,this sensor was further extended for glucose detection in diluted serum,which provides the possibility for practical applications in biological samples.3.We synthesized a high selective fluorescence probe to sense As?III?in environment.Using 2,5-dimethanethiolate terephthalic acid as a functional ligand,rare earth europium coordination polymer nanoparticles?Ce-CPNs?were synthesized by solvothermal method.In the absence of target,Ce-CPNs are in a dispersed state.Without target,Ce-CPNs is dispersive and shows a fluorescence peak at 353 nm under excitation at 280 nm.Contrarily,in the presence of As?III?,the dispersive Ce-CPNs are aggregated,accompanied by the quenching of fluorescent Ce-CPNs.Based on the high affinity of As?III?to sulfur and oxygen atoms as well as the analysis of experimental data,the fluorescence quenching mechanism could depend on the aggregation-caused?-?stacked layers of Ce-CPNs.Under optimal conditions,the detection limit for As?III?is down to 0.7 ppb.Further,the Ce-CPNs are selective for As?III?over other ions and has been successfully applied for fluorescence sensing As?III?in environmental water samples.4.A lanthanide cerium coordination polymers nanoparticles was synthesized for Hg²⁺detection.Due to the high affinity to rare earth ions,carboxylic acid,as a bridging ligand,can achieve intramolecular energy transfer between metal ions.Aromatic carboxylic acid ligands may indirect excite lanthanide ions though“antenna effect”,as a super sensitizer,which is also the most important part of the luminescent process of rare earth complexes.Thus,we synthesize cerium coordinate polymer nanoparticles?Ce?III?-CPNs?,which consisted by core ion of Ce³⁺and ligands of2-amino-terephthalic and glutaraldehyde.As the concentration of Hg²⁺is progressively increased,the fluorescent intensity of Ce?III?-CPNs is gradually quenched.The mechanism of quenching is that Hg²⁺combined with groups of ligand,which cause the intramolecular energy transfer from ligand to Ce?III?disrupt.Based on this,it relizes the detection of Hg²⁺.