Design Of Fluorescent Sensors Based On Self-Assembly Reaction And Internal Filtration Effect And Study On Analytical Methods

Fluorescent sensors have shown great application potential in many fields.For example food safety,metal ion detection,environmental pollution analysis and so on.Fluorescent sensors have advantages of high sensitivity,good selectivity,fast response and easy operation.Fluorescent probe is one of the most important factors that affect the sensing performance of fluorescent sensors.Therefore,the development of excellent performance fluorescent probes has been one of the important directions.Based on the molecular self-assembly fluorescence reaction between alizarin red S and pyridine boric acid,or the fluorescence internal filtration effect between alizarin red S and porphyrin,this thesis aims to design a novel fluorescence sensing system with excellent detection performance,and has carried out the following three works:（1）A fluorescence sensor was designed based on the molecular self-assembly fluorescence reaction between alizarin red S and pyridine boric acid.On this basis,an alkaline phosphatase induced enzyme-linked immunosorbent assay was developed with cardiac troponin I and COVID-19 N protein as model proteins.The LOD of cardiac troponin I was 0.03 ng·m L^-1,with a linear range of 2 to 175 ng·m L^-1.The detection limit of novel coronavirus N protein was 0.17 ng·m L^-1,and the linear range was 0.5～10 ng·m L^-1,Through the spiked recovery test,the relative standard deviation of alkaline phosphatase is less than 5%.The relative standard deviations of alkaline phosphatase,cardiac troponin I and novel coronavirus N protein were all lower than 5%,and the recoveries of standard addition were between 98%and 103%,indicating high precision,high accuracy and good reliability.It is expected to be applied to the detection of alkaline phosphatase,cardiac troponin I,and COVID-19 N protein in complex clinical samples.（2）Based on the enhancement effect of Al³⁺on the fluorescence reaction between alizarin red S and pyridine boric acid,the sensitivity of the designed fluorescence sensing system in the previous work was further improved.The concentration of alizarin red S and pyridine boric acid is reduced,and the detection cost is lower.Most improtant,the lower concentration of the probe,the higher sensitivity.There is a good linear relationship between the relative fluorescence intensity and the concentration of ALP within the range of 10 U·L^-1 to 800 U·L^-1,with LOD of 0.5 U·L^-1.This method has also been successfully applied to the detection of alkaline phosphatase in human serum.The relative standard deviation of this method is less than 4%through the spiked recovery test,indicating high precision.A spiked recovery rate is 99%～105%.This indicates high accuracy and reliability.It is expected that this method could be applied to detect target in complex clinical samples.（3）In order to improve sensitivity of melamine photometric analysis,a novel method of signal enhanced fluorescence analysis of melamine was established.The novel method using alizarin red S/melamine complex to inhibit the fluorescence internal filtration effect between alizarin red S and porphyrins.The detection performance of this sensor system was investigated.The linear range of melamine concentration was 0.5μmol·L^-1 to 10μmol·L^-1,and the detection limit was 0.04μmol·L^-1,which significantly reduced the detection limit and increased the sensitivity by about 100 times compared with alizarin red S spectrophotometry.It can be seen that the method has high accuracy and reliability,and is helpful for the detection of melamine in complex practical samples.This method has been successfully applied to the determination of melamine in commercially available milk.