pH-Responsive Self-Assembly of a Thiazole-Modified Peptide Nucleic Acid with Silver Ions

Herein, the pH-dependent self-assembly behavior of a thiazole-modified peptide nucleic acid (PNA) Thz-3 in the presence of silver ions (Ag⁺) is investigated. Using a combination of spectroscopy, microscopic imaging, and molecular dynamics simulations, the formation of entangled networks of long, interlinked linear structures of Thz-3 at pH 5.5 induced by Ag⁺ ions, is observed. This self-assembly is driven by intermolecular hydrogen bonding interactions and further stabilized by cation-π interactions between Ag⁺ and thiazole rings. Molecular clusters comprising two to four Thz-3 molecules are formed, which then organize into chain-like networks through noncovalent H-bonding and van der Waals interactions. These findings shed light on the development of selective and pH-responsive nanomaterials derived from modified peptides and PNAs.