From Protein Building Blocks to Functional Materials

Proteins are the fundamental building blocks for high performance materials in nature. Such materials fulfil structural roles, as in the case of silk and collagen, and can generate active structures including the cytoskeleton. Attention is increasingly turning to this versatile class of molecules for the synthesis of next generation green functional materials for a range of applications. Protein nanofibrils are a fundamental supramolecular unit from which many macroscopic protein materials are formed. In this review, we focus on the multiscale assembly of such protein nanofibrils formed from naturally occurring proteins into new supramolecular architectures and discuss how they can form the basis of material systems ranging from bulk gels, films, fibers, micro/nanogels, condensates and active materials. We review current and emerging approaches to process and assemble these building blocks in a manner which is different to their natural evolutionarily selected role, but allows the generation of tailored functionality, with a focus on microfluidic approaches. We finally discuss opportunities and challenges for this class of materials, including applications that can be involved in this material system which consists of fully natural, biocompatible and biodegradable feedstocks yet has the potential to generate materials with performance and versatility rivalling that of the best synthetic polymers

Controlled self-assembly of plant proteins into high-performance multifunctional nanostructured films.

Funder: Biotechnology and Biological Sciences Research CouncilThe abundance of plant-derived proteins, as well as their biodegradability and low environmental impact make them attractive polymeric feedstocks for next-generation functional materials to replace current petroleum-based systems. However, efforts to generate functional materials from plant-based proteins in a scalable manner have been hampered by the lack of efficient methods to induce and control their micro and nanoscale structure, key requirements for achieving advantageous material properties and tailoring their functionality. Here, we demonstrate a scalable approach for generating mechanically robust plant-based films on a metre-scale through controlled nanometre-scale self-assembly of water-insoluble plant proteins. The films produced using this method exhibit high optical transmittance, as well as robust mechanical properties comparable to engineering plastics. Furthermore, we demonstrate the ability to impart nano- and microscale patterning into such films through templating, leading to the formation of hydrophobic surfaces as well as structural colour by controlling the size of the patterned features

Biomolecular condensates undergo a generic shear-mediated liquid-to-solid transition.

Membrane-less organelles resulting from liquid-liquid phase separation of biopolymers into intracellular condensates control essential biological functions, including messenger RNA processing, cell signalling and embryogenesis1-4. It has recently been discovered that several such protein condensates can undergo a further irreversible phase transition, forming solid nanoscale aggregates associated with neurodegenerative disease5-7. While the irreversible gelation of protein condensates is generally related to malfunction and disease, one case where the liquid-to-solid transition of protein condensates is functional, however, is that of silk spinning8,9. The formation of silk fibrils is largely driven by shear, yet it is not known what factors control the pathological gelation of functional condensates. Here we demonstrate that four proteins and one peptide system, with no function associated with fibre formation, have a strong propensity to undergo a liquid-to-solid transition when exposed to even low levels of mechanical shear once present in their liquid-liquid phase separated form. Using microfluidics to control the application of shear, we generated fibres from single-protein condensates and characterized their structural and material properties as a function of shear stress. Our results reveal generic backbone-backbone hydrogen bonding constraints as a determining factor in governing this transition. These observations suggest that shear can play an important role in the irreversible liquid-to-solid transition of protein condensates, shed light on the role of physical factors in driving this transition in protein aggregation-related diseases and open a new route towards artificial shear responsive biomaterials

Controlled self-assembly of plant proteins into high-performance multifunctional nanostructured films

Funder: University of Cambridge | Darwin College, University of Cambridge (Darwin); doi: https://doi.org/10.13039/501100000595Funder: Federation of European Biochemical Societies (FEBS); doi: https://doi.org/10.13039/100012623Funder: EC | EC Seventh Framework Programm | FP7 Ideas: European Research Council (FP7-IDEAS-ERC - Specific Programme: "Ideas" Implementing the Seventh Framework Programme of the European Community for Research, Technological Development and Demonstration Activities (2007 to 2013)); doi: https://doi.org/10.13039/100011199; Grant(s): 337969Funder: RCUK | Biotechnology and Biological Sciences Research Council (BBSRC); doi: https://doi.org/10.13039/501100000268Abstract: The abundance of plant-derived proteins, as well as their biodegradability and low environmental impact make them attractive polymeric feedstocks for next-generation functional materials to replace current petroleum-based systems. However, efforts to generate functional materials from plant-based proteins in a scalable manner have been hampered by the lack of efficient methods to induce and control their micro and nanoscale structure, key requirements for achieving advantageous material properties and tailoring their functionality. Here, we demonstrate a scalable approach for generating mechanically robust plant-based films on a metre-scale through controlled nanometre-scale self-assembly of water-insoluble plant proteins. The films produced using this method exhibit high optical transmittance, as well as robust mechanical properties comparable to engineering plastics. Furthermore, we demonstrate the ability to impart nano- and microscale patterning into such films through templating, leading to the formation of hydrophobic surfaces as well as structural colour by controlling the size of the patterned features

Hierarchical propagation of structural features in protein nanomaterials

Natural high-performance materials have inspired the exploration of novel materials from protein building blocks. The ability of proteins to self-organize into amyloid-like nanofibrils has opened an avenue to new materials by hierarchical assembly processes. As the mechanisms by which proteins form nanofibrils are becoming clear, the challenge now is to understand how the nanofibrils can be designed to form larger structures with defined order. We here report the spontaneous and reproducible formation of ordered microstructure in solution cast films from whey protein nanofibrils. The structural features are directly connected to the nanostructure of the protein fibrils, which is itself determined by the molecular structure of the building blocks. Hence, a hierarchical assembly process ranging over more than six orders of magnitude in size is described. The fibril length distribution is found to be the main determinant of the microstructure and the assembly process originates in restricted capillary flow induced by the solvent evaporation. We demonstrate that the structural features can be switched on and off by controlling the length distribution or the evaporation rate without losing the functional properties of the protein nanofibrils

Hierarchical propagation of structural features in protein nanomaterials

Natural high-performance materials have inspired the exploration of novel materials from protein building blocks. The ability of proteins to self-organize into amyloid-like nanofibrils has opened an avenue to new materials by hierarchical assembly processes. As the mechanisms by which proteins form nanofibrils are becoming clear, the challenge now is to understand how the nanofibrils can be designed to form larger structures with defined order. We here report the spontaneous and reproducible formation of ordered microstructure in solution cast films from whey protein nanofibrils. The structural features are directly connected to the nanostructure of the protein fibrils, which is itself determined by the molecular structure of the building blocks. Hence, a hierarchical assembly process ranging over more than six orders of magnitude in size is described. The fibril length distribution is found to be the main determinant of the microstructure and the assembly process originates in restricted capillary flow induced by the solvent evaporation. We demonstrate that the structural features can be switched on and off by controlling the length distribution or the evaporation rate without losing the functional properties of the protein nanofibrils

Combination treatment with highly bioavailable curcumin and NQO1 inhibitor exhibits potent antitumor effects on esophageal squamous cell carcinoma

Background: Esophageal squamous cell carcinoma (ESCC) is one of the most intractable cancers, so the development of novel therapeutics has been required to improve patient outcomes. Curcumin, a polyphenol from Curcuma longa, exhibits various health benefits including antitumor effects, but its clinical utility is limited because of low bioavailability. Theracurmin® (THC) is a highly bioavailable curcumin dispersed with colloidal submicron particles. Methods: We examined antitumor effects of THC on ESCC cells by cell viability assay, colony and spheroid formation assay, and xenograft models. To reveal its mechanisms, we investigated the levels of reactive oxygen species (ROS) and performed microarray gene expression analysis. According to those analyses, we focused on NQO1, which involved in the removal of ROS, and examined the effects of NQO1-knockdown or overexpression on THC treatment. Moreover, the therapeutic effect of THC and NQO1 inhibitor on ESCC patient-derived xenografts (PDX) was investigated. Results: THC caused cytotoxicity in ESCC cells, and suppressed the growth of xenografted tumors more efficiently than curcumin. THC increased ROS levels and activated the NRF2–NMRAL2P–NQO1 expressions. Inhibition of NQO1 in ESCC cells by shRNA or NQO1 inhibitor resulted in an increased sensitivity of cells to THC, whereas overexpression of NQO1 antagonized it. Notably, NQO1 inhibitor significantly enhanced the antitumor effects of THC in ESCC PDX tumors. Conclusions: These findings suggest the potential usefulness of THC and its combination with NQO1 inhibitor as a therapeutic option for ESCC

Biotin levels in blood and follicular fluid

It has been shown that biotin, a water-soluble vitamin (B7), plays roles in reproductive functions, such as oocyte maturation and embryo development, in experimental animals. On the other hand, little is known about the clinical effects of biotin on human reproduction. In this study, serum and follicular fluid biotin levels were measured in patients who underwent in vitro fertilization / intracytoplasmic sperm injection (IVF / ICSI), and their associations with reproductive outcomes were evaluated. As a result, biotin was detected in follicular fluid, as well as serum, and the biotin levels of follicular fluid were found to be positively correlated with those of serum. The biotin levels of serum were higher than those of follicular fluid, suggesting that biotin may be taken up into the follicular fluid from the blood. Although serum and follicular fluid biotin levels tended to be higher in pregnant patients than in non-pregnant patients, these data did not show the significant statistical difference. These findings indicate that biotin does not contribute to the maintenance of oocyte quality, and hence, it does not increase fertilization and pregnancy rates

多職種連携と患者特性に配慮したケアを行った高度肥満症の一例

A ４８-year-old man who weighed ２１６ kg was significantly overweight with a body mass index （BMI）of ７５．６kg/m２, and was unable to walk due to disuse syndrome. Because of the psychological and social problems in the background, a psychological examination was performed and the staff took time to build a trusting relationship with the patient, taking into account his characteristics. With diet and rehabilitation, he was able to lose weight to １２４kg and BMI ４３．９kg/m２ over ６００ days, and was able to walk with assistive devices and defecate by himself. The patient was discharged from our hospital after a series of multidisciplinary meetings with medical, nursing, welfare, and governmental agencies to create an environment for home recuperation. The reasons for the improvement to enable him to be discharged from the hospital were due to the multi-disciplinary meetings among the staff inside and outside the hospital, information sharing and advanced coordination, and smooth communication with the patient by taking into account his characteristics from a psychological standpoint

Controlled self-assembly of natural proteins into hierarchically structured functional materials

Protein self-assembly offers key strategies for nature to generate high-performance and multifunctional proteinaceous materials. Inspired by nature’s approach, there is growing interest in the exploitation of self-assembled protein structures as a basis of artificial protein materials. To this end, this thesis aims to gain a better understanding of the nanofibrillar self-assembly of natural proteins and to develop new methods to utilise self-assembled structures for novel protein materials. The approach demonstrated here enabled an enhanced level of control over multi-scale protein assembly, leading to the creation of functional protein hydrogels, fibres and films, making them suitable for a wide range of applications. The first part of the thesis focuses on investigating the molecular self-assembly mechanism of silk fibroin, a natural protein used by silkworms to generate fibres. Through applying kinetic analysis, I demonstrated that the self-assembly process is dominated by a secondary process in which the formation of new fibrils is catalysed by the existing aggregates in an autocatalytic manner. In addition, I showed that hydrodynamic shear applied to protein molecules accelerates self-assembly by promoting primary nucleation. The results provided useful insights into nature’s strategies for controlling the assembly of proteins into materials. The second part describes the fabrication of silk-inspired protein-based microfibres using nanofibrils obtained from a milk-derived protein, β-lactoglobulin. The fibres were generated using a miniaturized fluidic device, which enables precise control of the hydrodynamic forces applied to the nanofibrils and thus replicates the natural spinning process of silk. By varying the flow rates, the degree of nanofibril alignment was tuned, leading to an orientation index comparable to that of native silk. It was further confirmed that this increased level of alignment led to enhanced mechanical properties in the fibre. The last part demonstrates a scalable method to induce and control the self-assembly of plant-derived proteins. Plant-derived proteins are attractive protein feedstocks as they can be sourced in a sustainable and low environmental impact manner. However, their poor water solubility poses fundamental challenges for controlling their self-assembly. The method developed in this project enables the dissolution of plant-derived proteins in aqueous solution with concentrations as high as 10w/v%, which can then undergo self-assembly into intermolecular β-sheet rich networks. The approach was further exploited to fabricate nanostructured hydrogels and films with advantageous mechanical and optical properties.Murata Scholarship, Japan Student Services Organization, Heiwa Nakajima Foundatio