A G4-quartet based hydrogel formed by self-assembly of borate esters of 5′-deoxy-5′-iodoguanosine (5′-IG 2) undergoes in situ cyclization to give 5′-deoxy-N3,5′-cycloguanosine (5′-cG 3). Formation of 5′-cG 3 causes self-destruction of the gel. This intramolecular cyclization can be used to release nucleoside analogs that have been pre-incorporated into the gel network.
