A label-free GR-5DNAzyme sensor for lead ions detection based on nanoporous gold and anionic intercalator.
A label-free electrochemical sensor, based on a classic lead ions (Pb2+)-dependent GR-5DNAzyme as the catalytic unit, disodium-anthraquinone-2,6-disulfonate (AQDS) as DNA intercalator, and nanoporous gold (NPG) for signal amplification, was designed for sensitive and selective detection of Pb2+. Firstly, NPG modified electrode surface were employed as a platform for the immobilization of thiolated probe DNA, and then, hybridized with DNAzyme catalytic beacons. The Pb2+-induced catalytic reaction makes the substrate strand break at the cleavage sitGe irreversibly, which disturbs the formation of DNA strands. AQDS served as an indicator that intercalated into the base-pairing regions of DNAzyme, resulting in a strong electrochemical signal. In the presence of Pb2+, the complementary regions were reduced, due to the fracture of the DNA strand, resulting in the release of AQDS. And a decreased current was obtained, corresponding to Pb2+concentration. Taking advantage of the amplification effect of NPG electrode for increasing the reaction sites of thiol modified capture probe, the proposed electrochemical biosensor could detect Pb2+quantitatively, in the range of 1-120nM, with a limit of detection as low as 0.02nM, which is much lower than the maximum contamination level for Pb2+in drinking water defined by the U.S. Environmental Protection Agency. The electrochemical sensor was also used to detect Pb2+from real water samples, and the results showed excellent agreement with the values determined by inductively coupled plasma mass spectroscopy. This biosensor showed a promising potential for on-site detecting Pb2+in aqueous environment.
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Yaoyu
Y
Zhou
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Jiachao
J
Zhang
College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082, China. Electronic address: tanglin@hnu.edu.cn.
Lin
L
Tang
College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082, China.
Bo
B
Peng
College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082, China. Electronic address: zgming@hnu.edu.cn.
Guangming
G
Zeng
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Lin
L
Luo
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Jun
J
Gao
Department of Biotechnology and Environmental Science, Changsha College, Changsha 410003, China.
Ya
Y
Pang
College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082, China.
Yaocheng
Y
Deng
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Fengfeng
F
Zhang
D015374:Biosensing Techniques / Q000379:methods*; D021881:DNA, Catalytic / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007364:Intercalating Agents / Q000737:chemistry*; D007854:Lead / Q000032:analysis*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D058608:Nanopores; D014874:Water Pollutants, Chemical / Q000032:analysis*
D021881:DNA, Catalytic; D007364:Intercalating Agents; D014874:Water Pollutants, Chemical; D007854:Lead; D006046:Gold
Anionic intercalator; GR–5DNAzyme; Label–free; Lead; Nanoporous gold