Switchable pH-Responsive Morphologies of Coassembled Nucleobase Copolymers.

Area of Science:

• Supramolecular chemistry
• Polymer science
• Nanomaterials engineering

Background:

• Nucleobase-containing polymers offer unique self-assembly properties.
• Controlling supramolecular morphology is crucial for advanced material design.
• pH-induced transitions in self-assembled systems are of significant interest.

Purpose of the Study:

• To synthesize and characterize supramolecular coassembled nucleobase copolymers.
• To investigate the effect of pH changes on copolymer morphology.
• To elucidate the role of intermolecular interactions in dictating assembly behavior.

Main Methods:

• Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization for copolymer synthesis.
• Preparation of coassemblies in aqueous buffers at pH 7.4 and 10.
• Morphological analysis of coassemblies.
• Isothermal titration calorimetry (ITC) to study binding interactions.

Main Results:

• Spherical morphologies formed at physiological pH (7.4).
• Increased pH (10) induced irreversible, anisotropic supramolecular architectures.
• Hydrogen bonds dominated assembly at pH 7.4, while hydrophobic interactions prevailed at pH 10.
• Morphology transitions were directly linked to the dominant interaction type.

Conclusions:

• Supramolecular interactions (H-bonds vs. hydrophobic) significantly influence nucleobase copolymer morphology.
• pH-triggered changes in interaction dominance lead to distinct supramolecular architectures.
• Findings provide insights for designing responsive nanomaterials with tunable properties.