Scheme 1.

Scheme of experimental setup showing Ag deposition experiments (Routes A and E) and control experiments (Routes B, C, and D): (A) Detection system with DNAzyme-based ON1 probe immobilized on AuNP. (B) Control experiment for Route A (no hemin). (C) Negative control (for Route E) with OT1 capture probe but without the OT2 DNAzyme probe addition. (D) Second negative control (for Route E) in the absence of OT1 capture probe but with OT2 G-quadruplex oligonucleotide. (E) Ag deposition system based on the OT1/OT2 hybridization approach.