Logic Catalytic Interconversion of G-Molecular Hydrogel

By incorporating hemin into G-quadruplex (G 4 ) during cation-templated self-assembly between guanosine and KB(OH) 4, we have constructed an artificial enzyme hydrogel (AEH)-based system for the highly sensitive and selective detection of Pb 2+ . The sensing strategy is based on a Pb 2+ -induced decrease in AEH activity. Because of the higher efficiency of Pb 2+ for stabilizing G 4 compared with K +, the Pb 2+ ions substitute K + and trigger hemin release from G 4, thus giving rise to a conformational interconversion accompanied by the loss of enzyme activity. The Pb 2+ -induced catalytic interconversion endows the AEH-based system with high sensitivity and selectivity for detecting Pb 2+ . As a result, the AEH-based system shows an excellent response for Pb 2+ 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 4 -DNAzyme. We also demonstrate that this AEH-based system exhibits high selectivity toward Pb 2+ 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 2+ or K + and pH. Given its versatility, this AEH-based system provides a novel platform for sensing and biomolecular computation.