Inducing Differential Self-Assembling Behavior in Ultrashort Peptide Hydrogelators Using Simple Metal Salts

Area of Science:

• Supramolecular chemistry
• Materials science
• Biomaterials engineering

Background:

• Controlling self-assembly is key to creating complex, multifunctional nanomaterials.
• Peptide hydrogels offer a versatile platform for bottom-up nanofabrication.
• Ion-responsive peptide amphiphiles are needed for tunable material properties.

Purpose of the Study:

• To investigate the role of metal ions and anions in modulating the self-assembly of histidine-containing peptide amphiphiles.
• To understand how ion interactions affect hydrogel properties like gelation pH and mechanical strength.
• To establish a bioinspired strategy for creating diverse, non-equilibrium nanostructures.

Main Methods:

• Rational design of peptide amphiphiles incorporating histidine for ion responsiveness.
• Systematic study of self-assembly behavior in the presence of various metal salts (e.g., Cu2+, Ni2+, Co2+, Fe2+, Mn2+).
• Analysis of ion effects on gel-to-sol transitions, gel strength, and nanostructure morphology, considering Irving-Williams and Hofmeister series.

Main Results:

• Histidine-containing peptide amphiphiles exhibited ion-dependent self-assembly.
• Stronger interactions with Cu2+, Ni2+, and Co2+ ions induced gel-to-sol transitions at physiological pH.
• Weaker interactions with Fe2+ and Mn2+ ions decreased gel strength but maintained gelation at physiological pH.
• Anions influenced nanostructure morphology and mechanical properties based on their water interactions.

Conclusions:

• The study demonstrates precise control over peptide hydrogel self-assembly using specific metal ions and anions.
• This ion-mediated approach offers a versatile strategy for bottom-up nanofabrication of advanced functional biomaterials.
• The findings pave the way for designing novel stimuli-responsive biomaterials with tunable properties.