Logic Catalytic Interconversion of G-Molecular Hydrogel.

By incorporating hemin into G-quadruplex (G) during cation-templated self-assembly between guanosine and KB(OH), we have constructed an artificial enzyme hydrogel (AEH)-based system for the highly sensitive and selective detection of Pb. The sensing strategy is based on a Pb-induced decrease in AEH activity. Because of the higher efficiency of Pb for stabilizing G compared with K, the Pb ions substitute K and trigger hemin release from G, thus giving rise to a conformational interconversion accompanied by the loss of enzyme activity. The Pb-induced catalytic interconversion endows the AEH-based system with high sensitivity and selectivity for detecting Pb. As a result, the AEH-based system shows an excellent response for Pb in the range from 1 pM to 50 nM with a limit of detection of ∼0.32 pM, which is much lower than that of the previously reported G-DNAzyme. We also demonstrate that this AEH-based system exhibits high selectivity toward Pb over other metal ions. Furthermore, two two-input INHIBIT logic gates have been constructed via switching of the catalytic interconversion induced by K and Pb or K and pH. Given its versatility, this AEH-based system provides a novel platform for sensing and biomolecular computation.