Hybrid Crosslinking of Collagen-Mimetic Peptides for Tunable Assembly and Enhanced Biopolymer Encapsulation

Collagen, the most abundant protein in the extracellular matrix of mammals, plays a vital role in maintaining cellular structure. Collagen-mimetic peptides (CMPs), synthetic biopolymers, have emerged as promising materials for biomedical applications because of their excellent biocompatibility, biodegradability, and tunable chemical and physical properties. In this study, a series of CMPs were designed using a Pro-Pro-Gly triplet-based template, incorporating lysine residues for Lys-glutaraldehyde (Lys-GTA) crosslinking and histidine residues for metal-His coordination to facilitate CMP assembly. To modulate the morphology of the assembled structures, peptides of varying lengths were synthesized and histidine residues within the CMP sequence were strategically positioned. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy confirmed that the designed CMPs assembled into distinct spherical structures under physiological conditions. The fluorescence measurements and confocal microscopy further demonstrated that these peptide-assembled spheres can encapsulate 40 K FITC-Dextran while forming large-scale structures. In summary, an effective strategy for assembling CMPs into higher-order spherical structures is developed by integrating Lys-GTA crosslinking with metal-His coordination. Notably, these assemblies exhibited the capability to encapsulate large biomolecules, offering valuable insights for the design of collagen-based biomaterials.