The Construction Of A Single Fluorescent Sensor With Discrimination And Recognition Controlled By Surfactant Assembly And Its Sensing Application

Major issues such as environmental pollution,disease infection,and food safety are closely related to people's life and have received increasing attention.Particularly,heavy metal pollution is a serious problem and widely existing in many areas,and its toxicity is heavy and difficult to remove,which has posed a serious threat to people's health.Therefore,identification and high-throughput detection of various metal ions is particularly important.Fluorescent sensor arrays with cross-reactive response are widely used to distinguish and identify metal ions.Amphiphilic surfactants are widely used in the preparation of fluorescent sensors because they can self-assemble in aqueous solution to form various well-organized aggregates,provide hydrophobic cavities,and solubilize various hydrophobic substances.In addition,surfactant assemblies can effectively modulate the photophysical properties and sensing behaviors of the encapsulated fluorescent probes,and therefore has many advantages in the construction of fluorescent sensors.However,the use of multi-element sensor arrays is usually accompanied with the issues of large sample consumption,complex data collection,and tedious processing procedures.Therefore,the development of single system-based cross-reactive fluorescent sensors is significant since they can not only distinguish and identify multiple analytes,but also avoid the above-mentioned problems.Based on the above consideration,this dissertation focused on developing discriminative single-system-based fluorescent sensors using the strategy of surfactant aggregates encapsulating fluorescent probes and modulating their photophysical properties,which are used to distinguish and identify different metal ions and analyze related actual samples.In the first part of the work,a pyrene-based fluorophore containing a metal ion acceptor,bis(2-methylpyridyl)amine group,is particularly designed and synthesized.The modulation effect of the anionic surfactant SDS on its photophysical properties was investigated,and a binary fluorescence sensing system with multiple emission bands was constructed.The ensemble sensor shows multiple wavelength cross-reactive responses to 13 tested metal ions including Mg2+,Al3+,Ca2+,Cr3+,Fe3+,Co2+,Ni2+,Cu2+,Zn2+,Cd2+,Ba2+,Hg2+ and Pb2+.The fluorescence variations at different wavelengths are taken as a response signal and collected to form a recognition fingerprint for each metal ion.PCA data processing enables the identification and discrimination of 13 metal ions.The sensor can also be used to distinguish between pure water and mineral water,as well as different brands of mineral water.Nuclear magnetic titration experiments,sensing performance of control compound-based binary ensemble,and time-resolved fluorescence decay tests revealed that the cross-reactive responses of the present sensing system is achieved due to the synergistic effect of the binding of bis(2-methylpyridyl)amine groups to metal ions and the regulation effect of SDS aggregates on the photophysical properties of the probe.Based on the similar design strategy,the second part of the work also aims to develop a cross-reactive single-system based fluorescent sensor with stronger discrimination ability using the synergistic effect of analyte receptors and surfactant modulation effect.Therefore,a receptor group for metal ions with more binding sites is introduced into the design of fluorescent probe.The modulation effect by anionic surfactant assemblies will be examined and the one that can produce multiple emission bands for the probe will be chosen to construct binary sensor.The cross-reactive responses to metal ions and discrimination ability of the binary sensor will be investigated so as to apply it to identify and recognize more metal ions in practical environments such as human serum and surface water such as rivers and lakes.