DNA hydrogels, consisting of Y-shaped nucleic acid subunits or of nucleic acid-functionalized acrylamide chains, undergo switchable gel-to-solution transitions. The Ag⁺-stimulated formation of cytosine–Ag⁺–cytosine complexes results in the crosslinking of the units to yield the hydrogels, while the cysteamine-induced elimination of the Ag⁺ ions dissociates the hydrogels into a solution phase.

A new siRNA delivery platform based on black phosphorus nanosheets is constructed which shows excellent therapy efficiency for tumors.