Controlling the Structure and Function of Protein Thin Films through Amyloid-like Aggregation

Abstract

Metrics & MoreArticle Recommendations CONSPECTUS: Protein thin films (PTFs) with tunable structure and function can offer multiple opportunities in various fields such as surface modification, biomaterials, packaging, optics, electronics, separation, energy, and environmental science. Although nature may offer a variety of examples of high-level control of structure and function, e.g., the S layer of cells, synthetic alternatives for large-area protein-based thin films with fine control over both biological function and material structure are a key challenge, especially when aiming for facile, low-cost, green, and large-scale preparation as well as a further extension of function, such as the encapsulation and release of functional building blocks. Therefore, regarding the structure and function of PTFs, we will first briefly comment on the problems associated with PTF fabrication, and then, regarding the basis of our long-term research on protein-based thin films, we will summarize the new strategies that we have developed in recent years to explore and control the structure and function of PTFs for frontier research and practical applications.Inspired by naturally occurring protein amyloid fibrillization, we proposed the amyloid-like protein aggregation strategy to assemble proteins into supramolecular 2D films with extremely large sizes and enduring interfacial adhesion stability. This approach opened a new window for PTF fabrication in which the spontaneous interfacial 2D aggregation of protein oligomers instead of traditional 1D protofibril elongation directs the assembly of proteins. As a result, the film morphology, thickness, porosity, and function can be tailored by simply tuning the interfacial aggregation pathways.We further modified amyloid-like protein aggregation to develop chemoselective reaction-induced protein aggregation (CRIPA). It is well known that chemoselective reactions have been employed for protein modification. However, the application of such reactions in PTF fabrication has been overlooked. We initiated this new strategy by employing thiol−disulfide exchange reactions. These reactions are chemoselective toward proteins containing specific disulfide bonds with high redox potentials, resulting in amyloid-like aggregation and thin film formation. Functional proteins with immunity to such reactions can be encapsulated in thin films and released on demand without a loss of activity, opening a new avenue for the development of functional PTFs and coatings. Finally, the resultant amyloid-inspired PTFs, as a new type of biomimetic materials, provide a good platform for integration with various biomedical functions. Here, the creation of bioactive surfaces on virtually arbitrary substrates by amyloid-like PTFs will be discussed, highlighting antimicrobial, antifouling, molecular separation, and interfacial biomineralization activities that exceed those of their native protein precursors and synthetic alternatives.

Adaptive liquid interfaces induce neuronal differentiation of mesenchymal stem cells through lipid raft assembly

“…The larger amide I/II ratio at pH 2 consistently shows a greater degree of protein conformational change than that at pH 5 24 . Thus, lysozyme is self-assembled at PFO mainly through β-sheet packing at pH 5 and through interprotein hydrophobic interactions at pH 2 25 .…”

Rectifying disorder of extracellular matrix to suppress urethral stricture by protein nanofilm-controlled drug delivery from urinary catheter

“…Here, we implemented surface modification by simply immersing any shape of material in a phase transition solution 23 , which was obtained by premixing BSA and SA, followed by the addition of TCEP aqueous solution (pH=4.5) (Fig. 1a).…”

“…1h), provided multiplex interfacial bonding sites for the nanofilm with underlying substrates 32 . Therefore, it enabled to modify the surface of virtually arbitrary material (including metal, organic or inorganic materials) through ligand bonding, electrostatic interaction, hydrophobic interaction and hydrogen bonding 23 . Quartz crystal microbalance with dissipation (QCM-D) also reflected such strong interfacial adhesion activity on the Au chip, as the adsorption amount of PTB@SA was significantly higher than that of native BSA (Supplementary Fig.…”

“…In this study, we propose a strategy to impart both anti-fibrotic and anti-biofilm activity to the catheter (in principle, being extendable to any other implants) by forming protein nanofilm coating on implant surfaces to noticeably control anti-fibrotic drug release, regulate tissue repair and finally prevent urethral stricture. Amyloid-like protein aggregation has been recognized as an excellent universal method to functionalize virtually arbitrary material surface 23 . In this way, we utilize unfolded bovine serum albumin (BSA) triggered by tris(2-carboxyethyl)phosphine (TCEP) to assemble a biocompatible protein nanofilm on the catheter.…”

Protein nanofibrils and their use as building blocks of sustainable materials

“… 241 In addition, there are new approaches that rely on the in situ assembly of amyloid-related structures at the air–water interface to create protein thin films. 242 Wang and co-workers demonstrated that functionalization of PNFs with hydrophobic dyes promotes formation of films at the air–water interface ( Fig. 14D ).…”