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Studies On Electrochemical Sensors For Rapid Detection Of Heavy Metal Ions

Posted on:2019-05-19Degree:MasterType:Thesis
Country:ChinaCandidate:Y LiuFull Text:PDF
GTID:2428330545959212Subject:Biomedical engineering
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Heavy metals,especially Cd2+,Pb2+and Hg2+,have attracted huge attention around the world for their high toxicity which impacts on human health directly or indirectly.Therefore,it is of great significance to pursue a fast,convenient,sensitive and efficient electrochemical biosensor for trace heavy metal ions detection.This dissertation intends to use the nano-porous pseudo carbon paste electrode?nano-PPCPE?to construct electrochemical sensor for cadmium ions,lead ions,mercury ions detection;at the same time,use the aptamer which can specifically identify heavy metal ions modified electrode to construct cadmium ions and mercury ions aptamer electrochemical sensor.And optimizing the experimental conditions.The main contents of this thesis are as follows:1.The preparation of nano-PPCPE and for Cd2+,Pb2+,Hg2+detection.The nano-porous pseudo carbon paste electrode?nano-PPCPE?was prepared with nano-CaCO3 microspheres as template and graphite powder as padding.The experimental results showed that the electrochemical performance of nanoPPCPE is evidently better than both glassy carbon electrode?GCE?and pure carbon paste electrode?CPE?.Then the prepared nanoPPCPE was applied to detect Cd2+,Pb2+and Hg2+in standard solution,the results showed that the electrode can quantitatively detect trace Cd2+and Pb2+,and qualitatively detect trace Hg2+,which has great significance in electrochemical analysis and detection.As the cadmium ion concentration range from 0.1 to 3.0?M,there is a linearity between the cadmium ions concentration and the DPV current,the linear equation is I?mA?=0.00267C+0.22443,the linear correlation coefficient is R=0.9960,the detection limit is 0.07978?M;As the lead ions concentration range from 0.05 to 4.0?M,there is a linearity between the lead ions concentration and the DPV current,the linear equation is I?mA?=0.00583C+0.21567,the linear correlation coefficient is R=0.9926,and the detection limit is 0.0298?M.The preparation of the nano-PPCPE is cheap,simple and has important practical value.2.The construction of cadmium ions aptamer electrochemical biosensor and its application.The cadmium ions aptamer electrochemical biosensor MCH/aptamer/D-?AuNPs/CS?/GCE had been constructed by using chitosan?CS?,AuNPs,cadmium ion aptamer,and mercaptohexanol?MCH?modify the surface of the glassy carbon electrode successively.Under optimum conditions,using DPV for cadmium ions detection,there is a linearity between the logarithm of cadmium ions concentration and the DPV peak current with cadmium ions concentration range from 0.001nM100 nM(1.12410-13 g/mL1.12410-8 g/mL),the linear equation is Ip??A?=11.54+0.8969lgC,the linear correlation coefficient is R=0.9947,and the detection limit is 0.04995 pM(5.61410-15 g/mL).Besides,the MCH/aptamer/D-?AuNPs/CS?/GCE was applied to detect cadmium ions in tap water samples,the results showed that the constructed aptamer electrochemical sensor has strong specificity for cadmium ions,and has the strong ability of anti-interference,good stability and repeatability,showing a good practical value which providing a newly idea and method for trace cadmium ions detection.3.The construction of mercury ion aptamer electrochemical biosensor based on T-Hg-T structure and its application.The mercury ion aptamer electrochemical biosensor had been constructed by using mercury ion aptamer modify the surface of D-?AuNPs/CS?/GCE,then specifically detect mercury ions using T-Hg-T structure.The experimental results showed that the mercury ions aptamer sensor obtain the best electrochemical performance when the D-?AuNPs/CS?/GCE surface modified with the medium density of mercury ions aptamer;the optimum incubation time of mercury ions and the aptamer sensor was 60 min;the DPV peak current of aptamer biosensor was positively correlated with the logarithm of mercury ion concentration,while mercury ion concentration range from 0.01 nM to 500 nM with a detection limit of 0.005 nM,the linear equation is Ip??A?=2.59902+0.2097lgC,the linear correlation coefficient is R=0.9994,and the detection limit is 0.005 nM.The constructed mercury ions aptamer sensor has a wide linear range and high sensitivity towards mercury ions,which provides a basis for trace mercury ions detection.
Keywords/Search Tags:heavy metal ions, nano-porous pseudo carbon paste electrode(nano-PPCPE), aptamer, electrochemical sensor, detection
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