Establishment Fluorescence Sensor For Several Drugsm Molecular Based On CdSe/ZnS Core-Shell Quantum Dots

In recent years,much attention has been paied to quantum dots,thanks to their unique optical and electrical properties.As semiconductor quantum dots,qua ntum dots have quantum yield,broad excitation spectrum and narrow emission s pectrum.Because of the optical properities,quantum dots have been widly applie d in the fields of different ions,biology molecular and drugs molecular,which h ave been widely used by researchers.The combination of quantum dots with dr ug,not only improved the biocompatible of quantum dots,but also could be us ed to detect drug molecules and montior the metabolism process of drug.In this article,three simple,sensitive and rapid fluorescence-sensor methods based on t he different combine with the target analytes for detection of dopamine,thiamine,folic acid were developed with the superior properties of CdSe/ZnS core-shell q uantum dots.1.By taking CdSe/ZnS core-shell quantum dots as a fluorescence probe,a methond for the rapid detection of fluorescence of dopamine was developed based on fluorescence quenching effect of dopamine to CdSe/ZnS core-shell quantum dots.Interestingly,it was found that dopamine could easily be oxidized by ambient O2 in alkaline solution,and oxidized dopamine to be electron acceptors for CdSe/ZnS core-shell quantum dots.Under the optimal experimental conditions(pH=7.4,reaction time : 20 min),the fluorescence quenching strength ratio of CdSe/ZnS core-shell quantum dots had a good linear relationship with concentration of dopamine in the range of 0.01 ~ 0.7 ?mol/L.The calibration equation was F0/F=2.51CDA+1.06,with a correlation coefficient(R)of 0.996.The detection limit was 1.6×10-4 ?mol/L.Compared with some approaches reported in current literatures,this method has a higher sensitivity.2.A new fluorescent probe analysis method for determination of thiamine was developed based on fluorescent quenching function of thiamine for CdSe/ZnS core-shell quantum dots.The fluorescence quenching was caused by the electrostatic interaction from thiamine to CdSe/ZnS core-shell quantum dots.Under the optimal conditions(pH7.4,reaction time of 25 min),when the concentration of thiamine is in the range of0.01 ~ 1 ?mol/L,the fluorescence quenching change strength of CdSe/ZnS core-shell quantum dots has a good linear relationship with concentration of thiamine :F0/F=0.67CVB1 +1.05(R=0.9992).The detection limit was 5.1×10-3 ?mol/L.Finally,this method was successfully used to detect thiamine in human urine.3.By taking CdSe/ZnS core-shell quantum dots as a fluorescence probe,a fluorescence sensor for the rapid detection of fluorescence of folic acid was developed based on fluorescence quenching effect of folic acid to CdSe/ZnS core-shell quantum dots.In NaH2PO4-Na2HPO4 buffer medium(pH 7.4),the quenched fluorescence intensity was linear with folic acid concentration in the range of 0.01 ~ 0.7 ?mol/L with correlation coefficient of 0.995.The limit of detection for folic acid was 2.01×10-4?mol/L.In this work,the reaction mechanism and the optimum of reaction condition were also investigated.The proposed fluorescence sensor was applied in the determination of folic acid in folic acid tablet and urine samples with satisfactory results.In a word,this paper structured fluorescence sensing detection system of dopamine,thiamine and folic acid based on CdSe/ZnS core-shell fluorescence quantum dots,and impact mechanism or method of electronic transfer,surface effect between target analyte and CdSe/ZnS core-shell quantum dots,in order to achieve a rapid detection of drugs molecular.These tentative works can supply a certain concept for expanding the application of quantum dots in pharmaceutical analysis.