Application Of Novel Terbium/europium Ratiometric Fluorescence Sensor In Environmental And Biological Analysis

The development of simple,rapid,highly sensitive and selective analytical methods is of great importance in the fields of environmental monitoring,food safety,and public health.The traditional fluorescence analysis method realizes the analysis and detection by recording the change of a single fluorescence signal,which can be interfered by environmental factors and instrument efficiency.The ratiometric fluorescence method establishes an internal standard by collecting two or more fluorescence signal changes of different wavelengths at the same time,so as to reduce or eliminate environmental and background interference and achieve more sensitive and reliable detection of target analytes.Lanthanide nanomaterials have broad application prospects in luminescent materials and fluorescence sensing due to their easy preparation,structural diversity and unique luminescence characteristics of lanthanide ions and organic ligands.Based on the excellent fluorescence properties of Tb³⁺and Eu³⁺,new lanthanide luminescent nanomaterial（Eu-PMA）is prepared in this paper,and the ratiometric fluorescence sensing platform is constructed for the analysis and detection of inorganic phosphate（Pi）,which is of great significance to environmental safety.Tb-DPA,Eu-DPA and Tb/Eu-DPA with green,red and light-yellow fluorescence are synthesized,and new“traffic light”ratiometric fluorescence sensing system is constructed for highly sensitive and selective detection of dopamine（DA）and biological sample analysis by introducing characteristic reactions,broadening the application of DA detection in initial monitoring and early clinical diagnosis of related diseases.Also,through the ratiometric fluorescence sensing platform combining characteristic reaction and“traffic light”probes,it is used for the ratiometric fluorescence and colorimetric dual-mode detection of tyrosinase（TYR）activity and related inhibitor screening,broadening the application of TYR detection in medical research and cosmetics industry.The ratiometric fluorescence method,which is constructed by combining characteristic reaction with fluorescent probe,not only improves the sensitivity and selectivity of detection,but also broads the application field of analysis and detection,and provides a new idea for designing optical sensors with excellent performance.The main research contents of this paper are summarized as follows:1.An optical sensor based on lanthanide light-emitting nanomaterials for detecting phosphate by ratiometric fluorescence methodInorganic phosphate（Pi）not only maintains physiological functions in organisms,but also serves as an indicator of water pollution in the environment.In this chapter,the lanthanide metal luminescent material Eu-PMA(PMA at 435 nm and Eu³⁺at 617 nm with characteristic fluorescence emission)is synthesized by a simple solvothermal method,which is used as a probe for detecting Pi by ratiometric fluorescence method.With the increase of Pi,Pi has a strong complexation ability with Eu³⁺,resulting in the structure damage of Eu-PMA,PMA cannot sensitize Eu³⁺luminescence,thus the fluorescence intensity of the system at 617 nm is significantly reduced,while the fluorescence intensity of ligand PMA at 435 nm is weakly increased through energy transfer interaction.According to the ratio of fluorescence intensity change of the two,the ratiometric fluorescence method is constructed to detect Pi.The ratiometric fluorescence method is not only rapid and simple,but also improves the sensitivity of Pi detection（Linear range is 0.1-90μM）,and is well applied to the analysis and detection of Pi content in actual water samples,which further broads the significance and application prospect of the ratiometric fluorescence method in detecting Pi.2.A“traffic light”signal ratiometric fluorescence sensor for highly sensitive and selective detection of dopamineAs a neurotransmitter with important biological properties,dopamine（DA）plays a vital role in the nervous system of the human body.In this paper,Tb-dipicolinic acid（DPA）,Eu-DPA,and Tb/Eu-DPA with green,red,and pale-yellow fluorescence are synthesized to construct new“traffic light”sensor for detecting DA,based on the characteristic reaction of resorcinol（Rs）and DA.Through the energy transfer and quenching effects,the fluorescence signals of the“traffic light”sensor are weakened,while the blue fluorescent product is enhanced.Moreover,the sensing systems show obvious chroma changes from green,red,and pale-yellow to blue,respectively.The ratiometric fluorescence signal change and chroma change enable the detection of DA with good sensitivity（The detection limits were 14.02 n M,3.011 n M and 4.020 n M）,and the participation of characteristic reaction makes the monitoring system have high selectivity and anti-interference ability.In addition,the method has good application for DA detection in serum samples and injection.More importantly,this study combines the“traffic light”sensor with characteristic reaction of Rs and DA,which not only broadens the applications of detecting DA in the initial monitoring and early clinical diagnosis of related diseases,but also provides a new idea for designing optical sensors with excellent performance based on characteristic reaction.3.“Traffic light”sensor for ratiometric fluorescence and colorimetric dual-readout detection of tyrosinase activityAs a biomarker of skin diseases,tyrosinase（TYR）has various biological functions by regulating the production of melanin.Here,new“traffic light”sensor for ratiometric fluorescence and colorimetric dual-mode detection of TYR activity was proposed by introducing characteristic blue fluorescence reaction.With increasing TYR,the fluorescent signals of“traffic light”probes（Tb-DPA,Eu-DPA,and Tb/Eu-DPA）are weakened,while the blue fluorescent signal is turned“on”,which improves the sensitivity and selectivity of ratiometric fluorescence sensing of TYR activity(low detection limits are 0.05012 U m L^-1 for Tb-DPA system,0.05035 U m L^-1 for Eu-DPA system,and 0.01043U m L^-1 for Tb/Eu-DPA system).And,colorimetric analysis of TYR activity is achieved by recording the absorbance values of the systems.Moreover,the colors of the“traffic light”systems are changed significantly from clear to dark-yellow under natural light,and under UV light,the distinct chromaticity changes from green,red,and pale-yellow to blue,respectively.This facilitates the visual analysis and qualitative detection of TYR.Furthermore,the“traffic light”sensor enables precise quantification of TYR in real samples.Subsequently,arbutin as an inhibitor sufficiently inhibited TYR activity.More importantly,this study not only realizes ratiometric fluorescence and colorimetric dual-mode detection and inhibition of TYR activity,but also broadens the application of TYR detection in medical research and cosmetic industries,as well as provides new ideas for the design of related optical devices.