Zinc(II)–Histidine Induced Collagen Peptide Assemblies: Morphology Modulation and Hydrolytic Catalysis Evaluation

Collagen-related materials have many potential biomedical applications because of their high biocompatibility and biodegradability. Designed collagen-mimetic peptides (CMPs) could self-assemble into supramolecular structures via a variety of interactions. In particular, metal-ligand interactions can induce microscale sizes of collagen assemblies. Our previous study also successfully applied metal-histidine coordination method to promote the self-assembly of CMPs into micrometers of constructs. In an effort to broaden the metal-induced strategies on assembling designed CMPs and explore the new insights into their assembly process, herein we designed and synthesized a series of short CMPs with one or more histidine residues incorporated into the peptides and used Zn(II) to induce the formation of collagen assembled microstructures. By altering the location and the number of histidine residues, we found that the assembly rate was significantly affected as well as the morphology of the assembled architectures. The CMPs containing terminal histidine residues were found to assemble into less ordered granulated and spherical microstructures while that with only one single histidine in its middle site could form pinwheel or floret-like constructs, showing that we could modulate the morphology of collagen assemblies by changing the location and number of Zn(II)-His coordination sites. Additionally, these CMPs also exhibited catalytic activities on ester hydrolysis in the presence of Zn(II) ions, which suggested that Zn(II)-CMP assemblies could be potentially applied to the development of artificial enzymes.