Nanofibrous chiral supramolecular assembly-derived self-healing hydrogels with polyethylene glycol

Abstract

Unique polymer hydrogels with unusual cross-linking networks and self-healing properties have been recently reported. In this study, we fabricated hybrid hydrogels consisting of a chiral supramolecular one-dimensional assembly of glutamide-derived lipids bearing pyridinium head groups (G-Py⁺) cross-linked with termini-anionised hydrophilic polyethylene glycol polymers (S-PEG_n-S). The cationic group-linked G-Py⁺ forms nanotubular aggregates in water. G-Py⁺/S-PEG_n-S aqueous mixtures formed hydrogels at certain concentrations and ambient temperatures. The terminal anionic sulfate groups play a key role in hydrogel formation, as evidenced by the absence of gelation in G-Py⁺/PEG_n. The negative circular dichroism signal observed for pyridinium exhibited a blue shift upon the addition of S-PEG_n-S but maintained its signal intensity even with excess S-PEG_n-S, suggesting the chiral orientation of the nanofibrous G-Py⁺ self-assembly preserved even complexation with S-PEG_n-S in hydrogel. The hybrid hydrogel of sulfated polyethylene glycol with nanofibrous chiral supramolecular assembly exhibited self-healing property at a temperature below the gel-to-liquid crystalline phase transition (T_C) of G-Py⁺ aggregates, which was evidenced by the inversion fluid method and viscoelastic measurements.