Selection of a metal ligand modified DNAzyme for detecting Ni2.

Nickel is a highly important metal, and the detection of Ni2+ using biosensors is a long-stand analytical challenge. DNA has been widely used for metal detection, although no DNA-based sensors were reported for Ni2+. DNAzymes are DNA-based catalysts, and they recruit metal ions for catalysis. In this work, in vitro selection of RNA-cleaving DNAzymes was carried out using a library containing a region of 50 random nucleotides in the presence of Ni2+. To increase Ni2+ binding, a glycyl-histidine-functionalized tertiary amine moiety was inserted at the cleavage junction. A representative DNAzyme named Ni03 showed a high cleavage yield with Ni2+ and it was further studied. After truncation, the optimal sequence of Ni03l could bind one Ni2+ or two Co2+ for catalysis, while other metal ions were inactive. Its cleavage rates for 100 μM Ni2+ reached 0.63 h-1 at pH 8.0. A catalytic beacon biosensor was designed by labeling a fluorophore and a quencher on the Ni03l DNAzyme. Fluorescence enhancement was observed in the presence of Ni2+ with a detection limit of 12.9 μM. The sensor was also tested in spiked Lake Ontario water achieving a similar sensitivity. This is another example of using single-site modified DNAzyme for sensing transition metal ions. Copyright © 2020 Elsevier B.V. All rights reserved.

Citation

Wei Ren, Po-Jung Jimmy Huang, Donatien de Rochambeau, Woohyun J Moon, Jinyi Zhang, Mingsheng Lyu, Shujun Wang, Hanadi Sleiman, Juewen Liu. Selection of a metal ligand modified DNAzyme for detecting Ni2. Biosensors & bioelectronics. 2020 Oct 01;165:112285

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PMID: 32510338

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