Fig. 7.

Representative DNAzyme sensors for metal-ion detection. (A) Florescence-based sensors for metal ions using a pair of fluorophore and quencher. Reprinted (adapted) with permission from J. Liu, A. K. Brown, X. Meng, D. M. Cropek, J. D. Istok, D. B. Watson and Y. Lu, A catalytic beacon sensor for uranium with parts-per-trillion sensitivity and millionfold selectivity, Proc. Natl. Acad. Sci. U. S. A., 2007, 104, 2056–2061.⁷⁵ (B) Colorimetric sensor based on gold nanoparticle aggregation and cleavage promoted disassembly. Reprinted (adapted) with permission from J. Liu and Y. Lu, A Colorimetric Lead Biosensor Using DNAzyme-Directed Assembly of Gold Nanoparticles, J. Am. Chem. Soc., 2003, 125, 6642–6643. Copyright 2003 American Chemical Society.⁴¹ (C) A multiplex DNAzyme sensor assay involving five DNAzymes. Reprinted (adapted) with permission from P. J. J. Huang, M. Vazin, J. J. Lin, R. Pautler and J. Liu, Distinction of Individual Lanthanide Ions with a DNAzyme Beacon Array, ACS Sens., 2016, 1, 732–738. Copyright 2016 American Chemical Society.²⁰⁸ (D) Use of a DNAzyme, fluorescent dyes and gold nanoparticles for the detection of Pb(II), Hg(II) and Ag(I) in a one-pot reaction. Reprinted (adapted) with permission from Y. Deng, Y. Chen and X. Zhou, Simultaneous sensitive detection of lead(II), mercury(II) and silver ions using a new nucleic acid-based fluorescence sensor, Acta Chim. Slov., 2018, 65, 271–277. Copyright 2018 Yuan Deng, Yinran Chen, Xiaodong Zhou.²⁰⁷