No abstract

Naturally sourced gels from food biopolymers have advanced in recent decades to compare favourably in performance and breadth of application to their synthetic counterparts. Here, we comprehensively review the constitutive nature, gelling mechanisms, design approaches, and structural and mechanical properties of food gels. We then consider how these food gel design principles alter rheological and tribological properties for food quality improvement, nutrient-modification of foods while preserving sensory perception, and targeted delivery of drugs and bioactives within the gastrointestinal tract. We propose that food gels may offer advantages over their synthetic counterparts owing to their source renewability, low cost, biocompatibility and biodegradability. We also identify emerging approaches and trends that may improve and expand the current scope, properties and functionalities of food gels and inspire new applications.

We report a new strategy for efficient removal of F− from contaminated water streams, and it relies on carbon hybrid membranes made of amyloid fibril/ZrO2 nanoparticles (<10 nm). These membranes exhibit superior selectivity for F− against various competitive ions, with a distribution coefficient (Kd) as high as 6820 mL g−1, exceeding commercial ion‐exchange resins (IRA‐900) by 180 times and outdoing the performance of most commercial carbon‐activated aluminum membranes. At both low and high (ca. 200 mg L−1) F− concentrations, the membrane efficiency exceeds 99.5 % removal. For real untreated municipal tap water (ca. 2.8 mg L−1) under continuous operating mode, data indicates that about 1750 kg water m−2 membrane can be treated while maintaining drinking water quality, and the saturated membranes can be regenerated and reused several times without decrease in performance. This technology is promising for mitigating the problem of fluoride water contamination worldwide.

Because of a large difference in storage modulus below and above the glass transition temperature, poly(acrylic acid-co-methyl methacrylate)/poly(ethylene glycol) (P(AA-co-MMA)/PEG) complexes show shape memory properties with a recovery ratio of nearly reach 99%. Before the shape memory testing, it was necessary to determine the conformational changes of the P(AA-co-MMA) gel induced by complexation with linear PEG. It was found that both the concentration and molecular weight of PEG have a strong effect on the complexation with P(AA-co-MMA) gel. In such a system the minimum molecular weight of PEG required for the complex formation lowers to 1000.

Amyloid fibrils have evolved from purely pathological materials implicated in neurodegenerative diseases to efficient templates for last-generation functional materials and nanotechnologies. Due to their high intrinsic stiffness and extreme aspect ratio, amyloid fibril hydrogels can serve as ideal building blocks for material design and synthesis. Yet, in these gels, stiffness is generally not paired by toughness, and their fragile nature hinders significantly their widespread application. Here we introduce an amyloid-assisted biosilicification process, which leads to the formation of silicified nanofibrils (fibril–silica core–shell nanofilaments) with stiffness up to and beyond ∼20 GPa, approaching the Young’s moduli of many metal alloys and inorganic materials. The silica shell endows the silicified fibrils with large bending rigidity, reflected in hydrogels with elasticity three orders of magnitude beyond conventional amyloid fibril hydrogels. A constitutive theoretical model is proposed that, despite its simplicity, quantitatively interprets the nonmonotonic dependence of the gel elasticity upon the filaments bundling promoted by shear stresses. The application of these hybrid silica–amyloid hydrogels is demonstrated on the fabrication of mechanically stable aerogels generated via sequential solvent exchange, supercriticalCO2removal, and calcination of the amyloid core, leading to aerogels of specific surface area as high as 993m2/g, among the highest values ever reported for aerogels. We finally show that the scope of amyloid hydrogels can be expanded considerably by generating double networks of amyloid and hydrophilic polymers, which combine excellent stiffness and toughness beyond those of each of the constitutive individual networks.

The propensity to self-assemble into amyloid fibrils with a shared cross-β architecture is a generic feature of proteins. Amyloid-related diseases affect millions of people worldwide, yet they are incurable and cannot be effectively prevented, largely due to the irreversible assembly and extraordinary stability of amyloid fibrils. Recent studies suggest that labile amyloids may be possible in certain proteins containing low-complexity domains often involved in the formation of subcellular membraneless organelles. Although the fundamental understanding of this reversible amyloid folding process is completely missing, the current view is that a given protein sequence will result in either irreversible, as in most of the cases, or reversible amyloid fibrils, as in few exceptions. Here we show that two common globular proteins, human lysozyme and its homologue from hen egg white, can self-assemble into both reversible and irreversible amyloid fibrils depending on the folding path followed by the protein. In both folding states, the amyloid nature of the fibrils is demonstrated at the molecular level by its cross-β structure, yet with substantial differences on the mesoscopic polymorphism and the labile nature of the amyloid state. Structural analysis shows that reversible and irreversible amyloid fibrils possess the same full-length protein sequence but different fibril core structures and β-sheet arrangements. These results illuminate a mechanistic link between the reversible and irreversible nature of amyloids and highlight the central role of protein folding states in regulating the lability and reversibility of amyloids.

The combination of chemotherapy and photothermal therapy (PTT) plays a significant role in synergistic tumor therapy. However, a high dosage of chemotherapy drugs or photothermal agents may cause series side effects. To overcome these challenges, we designed a near-infrared (NIR) responsive PEGylated gold nanorod (GNR-PEG) coated poly(l-lactide) microneedle (PLLA MN) system (GNR-PEG@MN) to enhance antitumor efficiency of docetaxel-loaded MPEG-PDLLA (MPEG-PDLLA-DTX) micelles for treating an A431 tumor. The as-made GNR-PEG@MNs contained only 31.83 ± 1.22 μg of GNR-PEG per patch and exhibited excellent heating efficacy both in vitro and in vivo. Meanwhile, GNR-PEG@MN with the height of 480 μm had good skin insertion ability and was harmless to the skin. On the other hand, GNR-PEG@MN had good heating transfer ability in vivo, and the tumor sites could reach 50 °C within 5 min. In comparison with chemotherapy and PTT alone, the combination of low dosage MPEG-PDLLA-DTX micelles (5 mg/kg) and GNR-PEG@MNs completely eradicated the A431 tumor without recurrence in vivo, demonstrating a remarkable synergetic effect. Hence, GNR-PEG@MN could be a promising carrier to enhance the antitumor effect of MPEG-PDLLA-DTX micelles for treating superficial tumors and is expected to have a great potential in clinical translation for human epidermoid cancer therapy.

Summary: This communication describes a novel kind of PMMA‐PEG semi‐interpenetrating network (semi‐IPN) which shows excellent shape‐memory behavior at two transition temperatures, the Tm of the PEG crystal and the Tg of the semi‐IPN. Based on a reversible order‐disorder transition of the crystals below and above the Tm of PEG, and the large difference in storage modulus below and above the Tg of the semi‐IPN, the polymer has a recovery ratio of 91 and 99%, respectively.