Amine-Functionalized Amyloid Aerogels for CO2 Capture

In Pursuit of Carbon Neutrality: Progresses and Innovations in Sorbents for Direct Air Capture of CO2

Direct air capture (DAC) is of immense current interest, as a means to facilitate CO2 capture at low concentrations (∼400 ppm) directly from the atmosphere, with the aim of addressing global warming caused by excessive anthropogenic CO2 production. Traditionally, DAC of CO2 has relied on amine scrubbing and metal carbonate /hydroxide solutions. However, recent years have seen notable progress in DAC sorbents, with key advancements aimed at improving efficiency, capacity, and regenerability while reducing energy consumption. This review delivers an exhaustive analysis of contemporary developments in DAC sorbents, addressing the innovations in material design and consequent performance enhancement. The limitations of the sorbents have also been discussed, with future perspectives for improving sustainable CO2 capture strategies. We anticipate that this overview will help lay the groundwork for further development and large-scale implementation of sustainable sorbents and cutting-edge technologies toward attaining carbon neutrality.

Nature-inspired recycling of a protein mixture into a green fluorescent protein-based hydrogel

Protein-based materials are biocompatible and have a variety of remarkable properties; consequently, they are finding more and more applications. Nature recycles proteins in multiple ways, ranging from bio-degradation (a slow approach) to fast recycling of protein metabolism. The latter is a wonderful example because a random mixture of proteins gets digested into amino acids (AAs), the fundamental building blocks of proteins. These AAs are then used by cells to produce whichever protein is needed at the time of synthesis. Seen through the lens of recycling, this process transforms a random mixture into something not necessarily present at the start but needed at the moment of recycling. We have recently shown that the process of protein recycling can be performed in vitro and called it NaCRe (Nature Inspired Circular Recycling). In a previous NaCRe proof-of-concept experiment, we started with various protein mixtures but were able to produce only small quantities of recycled protein, in the microgram scale. Here, we show that NaCRe can be used to convert milligrams of a protein mixture containing one of the most common protein materials (silk) into a milligram of an hydrogel made of green fluorescent protein (GFP). We show that in order for NaCRe to be efficient the starting protein mixture must contain a good balance of all AAs and discuss the challenges encountered when scaling up NaCRe.

Renewable biomass-based aerogels: from structural design to functional regulation

Global population growth and industrialization have exacerbated the nonrenewable energy crises and environmental issues, thereby stimulating an enormous demand for producing environmentally friendly materials. Typically, biomass-based aerogels (BAs), which are mainly composed of biomass materials, show great application prospects in various fields because of their exceptional properties such as biocompatibility, degradability, and renewability. To improve the performance of BAs to meet the usage requirements of different scenarios, a large number of innovative works in the past few decades have emphasized the importance of micro-structural design in regulating macroscopic functions. Inspired by the ubiquitous random or regularly arranged structures of materials in nature ranging from micro to meso and macro scales, constructing different microstructures often corresponds to completely different functions even with similar biomolecular compositions. This review focuses on the preparation process, design concepts, regulation methods, and the synergistic combination of chemical compositions and microstructures of BAs with different porous structures from the perspective of gel skeleton and pore structure. It not only comprehensively introduces the effect of various microstructures on the physical properties of BAs, but also analyzes their potential applications in the corresponding fields of thermal management, water treatment, atmospheric water harvesting, CO2 absorption, energy storage and conversion, electromagnetic interference (EMI) shielding, biological applications, etc. Finally, we provide our perspectives regarding the challenges and future opportunities of BAs. Overall, our goal is to provide researchers with a thorough understanding of the relationship between the microstructures and properties of BAs, supported by a comprehensive analysis of the available data.

Food Protein Nanofibril Gels: From Conditions, Types and Properties to Applications

Many food proteins can be assembled into nanofibrils under pH conditions far from the isoelectric point and with a low ionic strength by heating them for a long period. These food protein nanofibrils (FPN) have outstanding functional and biological properties and are considered sustainable biomaterials in many fields. In this study, we review the recent developments in FPN gels and introduce the key factors in promoting food protein self-assembly in order to create functional gels. The major variables discussed are the morphology of nanofibrils, protein concentration, heating time, and the type and concentration of salts. We also highlight current advances in the formation and properties of different types of FPN gels. In addition, the various applications of FPN gels in bioactive and nutrient delivery, adsorbents for CO2 and toxic pollutants, cell scaffolding biomaterials, biosensors, and others are introduced and discussed.

Functional Amyloids: The Biomaterials of Tomorrow?

Functional amyloid (FAs), particularly the bacterial proteins CsgA and FapC, have many useful properties as biomaterials: high stability, efficient, and controllable formation of a single type of amyloid, easy availability as extracellular material in bacterial biofilm and flexible engineering to introduce new properties. CsgA in particular has already demonstrated its worth in hydrogels for stable gastrointestinal colonization and regenerative tissue engineering, cell-specific drug release, water-purification filters, and different biosensors. It also holds promise as catalytic amyloid; existing weak and unspecific activity can undoubtedly be improved by targeted engineering and benefit from the repetitive display of active sites on a surface. Unfortunately, FapC remains largely unexplored and no application is described so far. Since FapC shares many common features with CsgA, this opens the window to its development as a functional scaffold. The multiple imperfect repeats in CsgA and FapC form a platform to introduce novel properties, e.g., in connecting linkers of variable lengths. While exploitation of this potential is still at an early stage, particularly for FapC, a thorough understanding of their molecular properties will pave the way for multifunctional fibrils which can contribute toward solving many different societal challenges, ranging from CO2 fixation to hydrolysis of plastic nanoparticles.