Supramolecular Hydrogel Inspired from DNA Structures Mimics Peroxidase Activity

We herein report that hydrogels can be prepared from guanosine and boronic acids in the presence of K⁺ and Pb²⁺ ions. These supramolecular hydrogels are formed via G-quartet like self-assembly of guanosine and its boronate esters. The potential of this hydrogel construct in mimicking enzyme-like activity has been demonstrated for the first time. We have observed that the self-assembled structure present in K⁺ stabilized hydrogel binds to iron­(III)-hemin and shows peroxidase activity, catalyzing oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂. Furthermore, the conformation of the G-quartet assemblies in the hydrogel can be altered by varying the stabilizing cations K⁺ and Pb²⁺. This conformational switching has been used to devise a molecular logic gate for sensing of toxic Pb²⁺ ions

A DNA-Inspired Synthetic Ion Channel Based on G–C Base Pairing

A dinucleoside containing guanosine and cytidine at the end groups has been prepared using a modular one-pot azide–alkyne cycloaddition. Single channel analysis showed that this dinucleoside predominantly forms large channels with 2.9 nS conductance for the transport of potassium ions across a phospholipid bilayer. Transmission electron microscopy, atomic force microscopy, and circular dichroism spectroscopy studies reveal that this dinucleoside can spontaneously associate through Watson–Crick canonical H-bonding and π–π stacking to form stable supramolecular nanostructures. Most importantly, the ion channel activity of this G–C dinucleoside can be inhibited using the nucleobase cytosine