Temporally Programmed Hydrogelation of a Short Peptide Charge Transfer Complex

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Chemical Engineering

Background:

• Mimicking dynamic biological systems with artificial constructs is a key challenge in supramolecular chemistry.
• Hydrogelation is a critical process for developing advanced materials with tunable properties.

Purpose of the Study:

• To design and characterize a novel charge transfer-driven hydrogelation system.
• To investigate the pH clock-regulation of hydrogel formation and disassembly.
• To explore the potential of this system in emulating dynamic biological assemblies.

Main Methods:

• Synthesis and characterization of pyrene-lysine cysteine tripeptide (PyKC) and phenylalanine-substituted naphthalene diimide (NDIF).
• Spectroscopic (UV-Vis, fluorescence) and structural (NMR, X-ray diffraction) analyses to confirm complex formation and assembly.
• pH-clock experiments using Tris buffer-glucono-δ-lactone to induce and control hydrogelation cycles.
• Temperature and pH-dependent studies to assess hydrogel reversibility.

Main Results:

• Formation of a 1:1 donor-acceptor complex between PyKC and NDIF via π-π stacking and β-sheet interactions.
• Rapid hydrogel formation under alkaline conditions with reversible transitions triggered by temperature and pH.
• Successful implementation of a pH clock for transient hydrogelation with tunable lifetimes.
• Demonstration of repeated, synchronized assembly and disassembly of the hydrogel in response to pH oscillations.

Conclusions:

• A novel supramolecular hydrogel system responsive to pH oscillations has been successfully developed.
• The charge transfer-driven mechanism and tunable properties make this system a promising platform for biomimetic applications.
• This work advances the design of dynamic artificial systems capable of emulating living assemblies.