Chemical unfolding of protein domains induces shape change in programmed protein hydrogels

• Published in: Nature communications Vol. 10; no. 1; pp. 5439 - 9
• Main Authors: Khoury, Luai R., Popa, Ionel
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.11.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 147/135; 631/57; 639/166/985; 639/301/357; 639/301/54; Animals; Biocompatible Materials; Biomaterials; Biomechanical Phenomena; Biomechanics; Biomedical materials; Bovine serum albumin; Cattle; Composite materials; Elasticity; Humanities and Social Sciences; Hydrogels; Hydrogels - chemistry; Hydrogels - metabolism; Lysine; multidisciplinary; Nanostructures; Organic chemistry; Poly-L-lysine; Polyelectrolytes; Polyethyleneimine; Polyethyleneimine - metabolism; Polylysine - metabolism; Protein engineering; Protein folding; Protein Unfolding; Proteins; Science; Science (multidisciplinary); Serum albumin; Serum Albumin, Bovine - chemistry; Serum Albumin, Bovine - metabolism; Shape memory; Stiffness
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-13312-0

Programmable behavior combined with tailored stiffness and tunable biomechanical response are key requirements for developing successful materials. However, these properties are still an elusive goal for protein-based biomaterials. Here, we use protein-polymer interactions to manipulate the stiffness of protein-based hydrogels made from bovine serum albumin (BSA) by using polyelectrolytes such as polyethyleneimine (PEI) and poly-L-lysine (PLL) at various concentrations. This approach confers protein-hydrogels with tunable wide-range stiffness, from ~10–64 kPa, without affecting the protein mechanics and nanostructure. We use the 6-fold increase in stiffness induced by PEI to program BSA hydrogels in various shapes. By utilizing the characteristic protein unfolding we can induce reversible shape-memory behavior of these composite materials using chemical denaturing solutions. The approach demonstrated here, based on protein engineering and polymer reinforcing, may enable the development and investigation of smart biomaterials and extend protein hydrogel capabilities beyond their conventional applications. Tailoring and programing the behavior of protein biomaterials is complex. Here, the authors report on the use of polyelectrolytes for controlling the stiffness to allow programing of protein hydrogels and generate reversible shape changes via folding and unfolding reactions.