Complex coacervates based on recombinant mussel adhesive proteins: their characterization and applications

Abstract

Complex coacervates are a dense liquid phase of oppositely charged polyions formed by the associative separation of a mixture of polyions. Coacervates have been widely employed in many fields including the pharmaceutical, cosmetic, and food industries due to their intriguing interfacial and bulk material properties. More recently, attempts to develop an effective underwater adhesive have been made using complex coacervates that are based on recombinant mussel adhesive proteins (MAPs) due to the water immiscibility of complex coacervates and the adhesiveness of MAPs. MAP-based complex coacervates contribute to our understanding of the physical nature of complex coacervates and they provide a promising alternative to conventional invasive surgical repairs. Here, this review provides an overview of recombinant MAP-based complex coacervations, with an emphasis on their characterization and the uses of such materials for applications in the fields of biomedicine and tissue engineering.

Recent Advances in Complex Coacervation Design from Macromolecular Assemblies and Emerging Applications

“…In generally, the coacervation results from a two‐step process: first, the charge neutralization of charged macromolecules dictated by electrostatic interactions and second, the entropic gain from release of bound counterion ( Figure ). [ 33 ] This process occurs via either spinodal decomposition, which does not involve an activation energy barrier, or nucleation and growth process whereby nuclei is formed first for phase separation. [ 34–36 ] Voorn, Veis, Tainaka, and co‐workers have put forward several theoretical models, respectively, in which the specific conditions, driving forces, formation process and phase separation kinetics have been discussed.…”

Fabrication and Mechanical Properties of Engineered Protein‐Based Adhesives and Fibers

“…Novel functional biomaterials have emerged to simulate and even surpass the mechanical properties of natural systems. Advances in genetic engineering have led to the development of recombinant protein‐based adhesives, in which the mechanical behaviors can be well controlled via their sequence and molar mass . The repeating natural or engineered amino acids of recombinant protein‐based adhesives endows them with biodegradable properties through natural pathways.…”

Macro- and Microphase Separated Protein-Polyelectrolyte Complexes: Design Parameters and Current Progress

“…The addition of a polyionic tag to a globular protein not only introduces a charge patch, but also adds an unstructured domain. Proteins that undergo simple coacervation naturally, such as mussel foot proteins (MFPs) and elastin like polypeptides (ELPs), tend to have unstructured, intrinsically disordered regions (IDRs) [21,50,51,52,53,54,55,56,57]. Native proteins that phase separate can de-mix by simple coacervation, but frequently the conditions under which phase separation occurs can be expanded via complex coacervation with an oppositely charged biopolymer.…”

“…Native proteins that phase separate can de-mix by simple coacervation, but frequently the conditions under which phase separation occurs can be expanded via complex coacervation with an oppositely charged biopolymer. For example, MFP-1 undergoes complex coacervation with hyaluronic acid [21,50]. This ability has increased interest in developing recombinant mussel foot proteins for various complex coacervate-based applications, such as bio-based adhesives [50].…”

“…For example, MFP-1 undergoes complex coacervation with hyaluronic acid [21,50]. This ability has increased interest in developing recombinant mussel foot proteins for various complex coacervate-based applications, such as bio-based adhesives [50]. Some proteins, such as Whi3 and LAF-1 not only have regions of disorder but also have RNA binding domains that facilitate complexation and phase separation with RNA [58,59].…”