Controlling Polymer Morphologies by Intramolecular and Intermolecular Dynamic Covalent Iron(III)/Catechol Complexation – From Polypeptide Single Chain Nanoparticles to Hydrogels

Responsive biomaterials, tunable from the molecular to the macroscopic scale, are attractive for various applications in nanotechnology. Herein, a long polypeptide chain derived from the abundant serum protein human serum albumin was cross-linked by dynamic-coordinative iron(III)/catechol bonds. By tuning the binding stoichiometry and the pH, reversible intramolecular folding into polypeptide nanoparticles with controllable sizes was achieved. Moreover, upon varying the stoichiometry, intermolecular cross-links became predominant yielding smart and tunable macroscopic protein hydrogels. By adjusting the intra-and intermolecular interactions, biocompatible and biodegradable materials were formed with varying morphologies and dimensions covering several lengths scales featuring rapid gelation without toxic reagents, fast and autonomous self-healing, tunable mechanical properties and high adaptability to local environmental conditions. Such material characteristics could be particularly attractive for tissue engineering approaches to recreate soft tissues matrices with highly customizable features in a fast and simple fashion.