Switchable pH-Responsive\nMorphologies of Coassembled\nNucleobase Copolymers

This work presents supramolecular coassembled nucleobase\ncopolymers\nwith transitional morphologies upon pH changes (from 7.4 to 10). Uracil-\nand adenine-containing copolymers were prepared by RAFT, which allowed\nus to finely tailor the polymerization degree and the composition.\nThe coassembled formulations prepared in an aqueous buffer at two\ndistinct pH (7.4 and 10) formed spherical morphologies at physiological\npH. The increase of the pH induced the apparition of various large,\nirreversible anisotropic supramolecular architectures. Isothermal\ntitration calorimetry revealed that the coassembly at pH 7.4 was mainly\nguided by H-bonds between complementary nucleobases, while the experiments\nconducted at pH 10 showed that the assemblies were mainly driven by\nhydrophobic interactions. These results highlight that the nature\nof supramolecular interactions (H-bonds or hydrophobic interactions)\nhas a great influence on the morphology of nucleobase-containing coassemblies\nwhen changing the pH. These findings may provide further perspectives\nin the field of advanced nanomaterials.