The Synthesis And Application Of A Fluorescent Chemosensor For L-Cysteine

L-Cysteine is of great importance thiol-containing ?-amino acid,which plays numerous important roles in human body,such as participates in protein synthesis,detoxification,metabolism and so on.L-Cysteine can be found in many proteins throughout the human body and is one of the most important constituents of biologically relevant proteins.L-Cysteine also helps to maintain intracellular redox activity,intracellular signal transduction and gene regulation.If content of L-cysteine in cells deviate from the normal level will result in a number of diseases,endangering the health of human body.Meanwhile,L-cysteine is also widely applied to the food industry,bio-pharmaceutical,biological and chemical research and other fields.Therefore,establishing a simple and selective method for the detection of L-cysteine is a very meaningful work.Fluorescent chemosensor has the advantages of simple operation,high sensitivity,good selectivity,short response time and real-time detection.It has been widely used in the detection of trace species in the environment,food and living body.In this paper,we designed and synthesized 2,2'-?[1,1'-biphenyl]-2,2'-diylbis?oxy??bis?N-?quinolin-8-yl?acetamide??L?as a ligand,and used the complex of L and Cu²⁺ as a fluorescent probe to detect the content of L-cysteine.And the fluorescence spectral properties,recognition performance,sensing mechanism and application in real samples were systematically studied.In the first chapter,we carried out an overview of L-cysteine including the important roles and some disadvantages it will produce.Detection methods and research progress in fluorescent chemosensors of L-cysteine were introduced in detail.In the second chapter,we mainly introduced the synthesis method of ligand L and its intermediate and characterized these compounds by MS,1H NMR and 13 C NMR.In the third chapter,we systematically studied the detection performance of L-Cu²⁺ on L-cysteine,optimized the experimental conditions,investigated the selectivity and anti-interference ability of the sensor,discussed the sensing mechanism and applied it to real samples determination.At room temperature,in PBS buffer solution?water/acetonitrile,9:1 v/v;PBS 0.02 mol/L;p H = 8.0?,the recovered fluorescence intensity of the L-Cu²⁺ system is linear to the concentration of L-cysteine in the ranges of 1.0×10-6 mol/L to 8.0×10-6 mol/L.The detection limit for L-cysteine is 1.92×10-7 mol/L.The sensor showed good selectivity to L-cysteine and good anti-interference ability to other coexisting amino acids.The possible sensing mechanism was proposed by Job?s Plot and mass spectrometry analysis.The recoveries in real samples were found to be in the range 99.2–102.1%,with RSD values ranging from 0.94% to 1.52%,which proves its practicality in real samples.