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| Detection of Lead Ion Using a Label-free Aptamer Electrochemical Sensor Based on Hybridization Indicator |
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| DOI： |
| KeyWord:lead ion aptamer electrochemical sensor hybridization indicator |
| Author | Institution |
| ZHANG Yu-ting，CHEN Hao-han，LI Hui，WANG Xiao-li，ZHOU Nan-di |
School of Biotechnology，Key Laboratory of Carbohydrate Chemistry and Biotechnology，Ministry of Education，Jiangnan University，Wuxi ，China |
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| Abstract: |
| To realize the online analysis of heavy metal lead ion（Pb2+），a label-free aptamer electrochemical sensor was constructed with the hybridization indicator methylene blue（MB） as the electrochemical signal probe and the aptamer as the recognition element of Pb2+．On the surface of the gold electrode，the aptamer and its complementary sequence cDNA were successively modified to form a double strand，and then the MB adsorbed between the double strands produced a strong electrochemical signal．In the presence of Pb2+，the aptamer specifically captured Pb2+ and released MB，resulting in the decrease of the electrical signal so as to realize the quantitative detection of Pb2+．Electrochemical impedance spectroscopy and cyclic voltammetry were performed to characterize the successful development of the constructed aptamer electrochemical sensor，while the feasibility of the sensor was proved by PAGE gel electrophoresis analysis．Differential pulse voltammetry was applied to record the electroactive signal of MB in Tris－HCl buffer solution．After optimization，the optimal experimental conditions of the aptamer electrochemical sensor were as follows：incubation time of cDNA：120 min；concentration of MB：1.6 mmol/L；incubation time of MB：120 min；incubation time of Pb2+：60 min．The linear response range for the sensor to Pb2+ was 0.1－100 000 μg/L，and the limit of detection was as low as 33.4 ng/L．The results of the specificity test showed that the other interfered metal ions play a non-obvious effect on Pb2+ detection．The proposed method was applied to the determination of Pb2+ in milk samples and lake water samples．The spiked recoveries were in the ranges of 87.1%－115% and 106%－108%，with their relative standard deviations（RSDs） of 10%－13% and 5.0%－9.5%，respectively．The label-free aptamer electrochemical sensor constructed in this paper exhibits the advantages of low cost，sensitivity and rapidity，which is expected to be employed in the field analysis of Pb2+ in the environment and food industry. |
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