Peptide-polyurea hybrids: a platform for tunable, thermally-stable, and injectable hydrogels

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Supramolecular Chemistry

Background:

• Designing strong, dynamic biomaterials often involves drawing inspiration from natural segmented structures like silk fibroin.
• Polymer-peptide hybrids combine synthetic advantages with hierarchical polypeptide structures, showing promise for biocompatible and tunable hydrogel systems.

Purpose of the Study:

• To demonstrate the utility of poly(ethylene glycol) (PEG) peptide-polyurea (PPU) hybrids as self-assembled hydrogels.
• To systematically examine how peptide secondary structure and segment length influence PPU hydrogelation, microstructure, and rheological properties.

Main Methods:

• Utilized triblock copolymers, specifically poly(ε-carbobenzyloxy-L-lysine)-b-PEG-b-poly(ε-carbobenzyloxy-L-lysine) and poly(β-benzyl-L-aspartate)-b-PEG-b-poly(β-benzyl-L-aspartate), as soft segments in linear PPU hybrids.
• Investigated hydrogelation, microstructure, and rheological properties by varying peptide secondary structure and segment length.
• Performed simulated injection experiments and thermal stability tests.

Main Results:

• Polymers with α-helical secondary structures exhibited rapid gelation upon water addition, driven by hierarchical assembly.
• Peptide segment length influenced gel strength and deformation resistance through complex relationships.
• PPU hydrogels demonstrated rapid network recovery (<10 s) after high shear and maintained solid-like properties from 10-80 °C, with a softening transition near secondary structure melting.

Conclusions:

• The developed bioinspired PPU hybrid platform enables the design of synthetic polymers with tunable microstructure and mechanics.
• These hydrogels offer opportunities for applications requiring specific thermal properties and injectability.
• The study highlights the potential of hierarchical assembly in peptide segments for creating advanced biomaterials.