Application Of Cation-Exchange Reaction Of CuS Nanoparticles And Fluorescent Copper In Sensing Analysis

Fluorescence nanomaterials with DNA as templates have become a hotspot in the field of chemistry.Because of their good molecular assembly recognition ability,unique nano-size and excellent biocompatibility and other advantages,fluorescence nanomaterials has been very widely used in various fields.The researches show that poly T can be used as a template for the synthesis of fluorescent copper nanoparticles,and the synthesis speed is rapid and the reaction conditions are mild.So it is often used as a fluorescent indicator probe and widely used in biosensors.Metal ion nanoparticles generally have a relatively large specific surface area,therefore,without the presence of enzyme and other catalysts,cation-exchange(CX)reactions could occur completely and quickly at room temperature.The reaction time is short,the amount of released metal ions is very large.The main idea of the reseach is using cation-exchange reaction between CuS nanoparticles and AgNO3,to release large amounts of Cu2+ quickly.Then,the released Cu2+ and poly T can be rapidly reduced into fluorescent copper nanoparticles in the presence of reducing agent.Fluorescence signal can be obtained at 625 nm.1.In this experiment,acetylcholinesterase can hydrolyze the thioacetylcholine to produce thiocholine.Thiocholine contains thiol and the thiol can be combined with Cu2+ to produce a complex,which inhibits the formation of fluorescent copper nanoparticles.When acetylcholinesterase inhibitors are added,the activity of acetylcholinesterase is inhibited,and it can not hydrolyze thioacetylcholine to form thiocholine,and the fluorescent copper nanoparticles is no longer produced.Using this feature,a well-designed and easy-to-use experiment was designed to detect the activity of acetylcholinesterase and its inhibitors.The results showed that when theconcentration of acetylcholinesterase ranging from 0.05 U·L-1 to 6.0 U·L-1,the concentration of acetylcholinesterase had a good linear relationship with the fluorescence intensity of the system.2.In this part,the Exo III cycling reaction was combined with cation exchange technology.A signal probe was designed and synthesized,which was introduced into the experimental reaction.After a series of cyclic reactions,the experimental signal was converted into fluorescence signal of fluorescent copper nanoparticles in presence of target DNA.The experimental results show that when the concentration of DNA concentration ranging from 1.0 × 10-9 M to 1.0 × 10-6 M,the logarithm of the target DNA concentration had a good linear relationship with the fluorescence intensity of the system.The experimental method has good selectivity and specificity.The detection can be porformed for the real sample.3.The Exo III series cyclic amplification reaction was combined with cation exchange technology,a new biosensor for the detection of DNA was redesigned on the basis of the previous experiment.The introduction of cyclic II resulted in a significant increase in the amount of Cu2+ produced by the cation-exchange reaction,achieving the signal amplification.Finally,the fluorescence characteristics of the fluorescent copper nanoparticles were detected.The concentration range of the detected target DNA is wider than before,the detection sensitivity is improved.The results showed when the concentration range of target DNA concentration ranging from 1.0 × 10-11 M to 1.0 × 10-6 M,the logarithm of the target DNA concentration had a good linear relationship with the fluorescence intensity.