Figure 6.

(a) Schematic diagram of G4 DNAzymes for Pb²⁺ detection based on the competition between K⁺ and Pb²⁺ stabilized G4. Reprinted with permission from Ref. [90]. Copyright 2019 Springer; (b) Mechanism assay for OTA detection by exonuclease-assisted multicolor aptasensor. Reprinted with permission from Ref. [84]. Copyright 2018 Springer.