We developed this system further to minimize the background activity by combining the HRP DNAzyme with an F8 ribozyme.Wang2014 This way the stem that avoids the formation of the G-quadruplex can be designed stronger, as the F8 DNAzyme is able to cleave of a part of this stem. This results into a weakening of the stem that inhibits HRP-mimicking DNAzyme activity and thus to the formation of the G-quadruplex. The F8 DNAzyme was fused with aptamers so that in the presence of the ligand the F8 DNAzyme becomes active which then activates the HRP-mimicking DNAzyme (Fig. 6).
Just as the HRP DNAzyme other DNAzymes like the RNA-cleaving DNAzymes 7-18 and 10- 23 DNAzyme can be modified to become ligand dependent.Wanga2002 Many more candidates like the ones described by Wang et al. can be used for multiplexed detection of small molecules with our visualization method on the blot.
