Ion-Induced Morphological Plasticity in a Self-Assembling Peptide Hydrogel

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Biomaterials Engineering

Background:

• Hydrogels are versatile soft materials with applications in various fields.
• Controlling hydrogel morphology and properties at the nanoscale is crucial for advanced applications.
• Peptide-based hydrogels offer biocompatibility and tunable self-assembly characteristics.

Purpose of the Study:

• To investigate the stimuli-responsive behavior of a peptide hydrogel in the presence of different metal ions.
• To elucidate the ion-specific mechanisms governing morphological and mechanical changes in the hydrogel.
• To explore the potential of this adaptive hydrogel for biomedical and sensing applications.

Main Methods:

• Transmission electron microscopy (TEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and X-ray diffraction (XRD) for structural analysis.
• Atomistic molecular dynamics simulations to understand nanoscale transitions.
• Mechanical testing to evaluate hydrogel properties after ion exposure.

Main Results:

• Monovalent and trivalent ions induced a morphological transformation from nanofibers to nanospheres.
• Divalent ions triggered syneresis (shrinking) and a shift to nanoribbon morphology.
• Ion-peptide interactions were confirmed to control nanoscale morphology, network architecture, and mechanical performance.
• Hydrogels with mono- or trivalent ions showed enhanced thermal and mechanical stability.
• Syneresis in divalent ion-containing gels acted as a postassembly strengthening mechanism, increasing stiffness.

Conclusions:

• Peptide hydrogels exhibit remarkable ion-specific stimuli-responsiveness and morphological plasticity.
• Ion-peptide interactions are key to orchestrating the material's properties at multiple length scales.
• This adaptive hydrogel system offers tunable physicochemical properties and opens avenues for advanced applications in biomedicine and sensing.