In Vitro Selection and Characterization of Highly Selective Metal -Dependent DNAzymes With Potential Biosensor Applications

Abstract

A separate in vitro selection experiment was carried out in the presence of Pb2+ in order to compare the secondary structures of the resulting DNAzymes with the structure of the 8-17-like DNAzymes, which were selected through three independent experiments in the presence of: (1) Zn2+, (2) Mg2+, and (3) histidine plus Mg2+. The DNAzymes obtained from this experiment did not appear to contain the secondary structure of the 8-17 catalytic core. The reason for this is unclear, although one possibility is that the larger random region in the initial pool may have allowed for more sequence and structural diversity in the initial pool. The DNAzymes examined displayed higher specificity and lower sensitivity for Pb2+ compared to the 8-17 DNAzyme. The sensitivity may be improved through more stringent selection conditions. This work may eventually lead to an improved Pb2+ biosensor that does not display significant activity with contaminating metal ions.