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. Author manuscript; available in PMC: 2020 Oct 21.
Published in final edited form as: Inorg Chem. 2019 Jul 31;58(20):13696–13708. doi: 10.1021/acs.inorgchem.9b01280

Figure 2.

Figure 2.

Important advancements for DNAzyme-based metal sensors in cells. (A) First cellular detection of metal ions with a DNAzyme catalytic beacon probe (39E) by conjugation to AuNPs for imaging of UO22+ in cellular lysosomes. Reproduced with permission from reference 103. Copyright 2013 American Chemical Society. (B) A photocaging strategy for the catalytic beacon to inactivate DNAzyme cleavage by “caging” the RNA 2ʹ-OH with a nitrobenzyl group. 365nm light irradiation (hν) is used to restore the 2ʹ-OH of the rA cleavage site. The DNAzyme is then able to cleave its substrate in the presence of its specific metal ion (M2+), producing the fluorescence signal. Reproduced with permission from reference 105. Copyright 2014 Wiley-VCH. (C) Amplification strategy to increase the DNAzyme probe sensitivity using Catalytic Hairpin Assembly (CHA). Release of the cleaved substrate strand initiator (I, red) generated by metal-dependent DNAzyme activity allows for toehold-mediated strand displacement opening of hairpin 1 (H1, blue) which can further open the reporter hairpin 2 (H2, green), separating the fluorophore (F) and quencher (Q) to produce the fluorescent signal. Reproduced with permission from reference 117. Copyright 2017 Wiley-VCH.