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Tardigrades are microscopic animals that survive desiccation by inducing biostasis. To survive drying tardigrades rely on intrinsically disordered CAHS proteins, which also function to prevent perturbations induced by drying in vitro and in heterologous systems. CAHS proteins have been shown to form gels both in vitro and in vivo, which has been speculated to be linked to their protective capacity. However, the sequence features and mechanisms underlying gel formation and the necessity of gelation for protection have not been demonstrated. Here we report a mechanism of fibrillization and gelation for CAHS D similar to that of intermediate filament assembly. We show that in vitro, gelation restricts molecular motion, immobilizing and protecting labile material from the harmful effects of drying. In vivo, we observe that CAHS D forms fibrillar networks during osmotic stress. Fibrillar networking of CAHS D improves survival of osmotically shocked cells. We observe two emergent properties associated with fibrillization; (i) prevention of cell volume change and (ii) reduction of metabolic activity during osmotic shock. We find that there is no significant correlation between maintenance of cell volume and survival, while there is a significant correlation between reduced metabolism and survival. Importantly, CAHS Ds fibrillar network formation is reversible and metabolic rates return to control levels after CAHS fibers are resolved. This work provides insights into how tardigrades induce reversible biostasis through the self-assembly of labile CAHS gels.

Calcium–alumino–silicate–hydrate (CaO–Al2O3–SiO2–H2O, or C–A–S–H) gel, which is the binding phase of cement-based materials, greatly influences concrete mechanical properties and durability. However, the atomic-scale kinetics of the aluminosilicate network condensation remains puzzling. Here, based on reactive molecular dynamics simulations of C–A–S–H systems formation with varying Al/Ca molar ratios, we study the kinetic mechanism of the hydrated aluminosilicate gels upon precipitation. We show that the condensation activation energy decreases with the Al/Ca molar ratio, which suggests that the concentration of the Al polytopes has a great effect on controlling the kinetics of the gelation reaction. Significantly, we demonstrate that 5-fold Al atoms are mainly forming at high Al/Ca molar ratios since there are insufficient hydrogen cations or extra calcium cations to compensate the negatively charged Al polytopes at high Al/Ca molar ratios during accelerated aging. [ABSTRACT FROM AUTHOR]

Micelles of anionic or zwitterionic surfactants produced depletion interactions between nanofibrils leading to weak gels, while cationic surfactants adsorbed to the nanofibrils, screening repulsions leading to tough gels or phase separation. Are fundamentally and technologically interesting due to their diverse building blocks, network-supporting attractive forces, and gelation pathways. As described below, the 29 articles that appear in this issue shed new light on a wide variety of related topics, including limited valence networks, bridged colloidal networks and coagulant gels, depletant-mediated gels, I in situ i structural characterization of gel aging, mechanical and rheological properties of colloidal networks, hybrid and deformable particle assemblies, and nanocrystal gels with tunable optical response. Bridged networks and coagulant gels Colloidal networks formed by nonspecific bridging polymers represent another interesting class of gel formers, although it can be challenging to design dispersible systems with tunable polymer-colloid interactions. [Extracted from the article]

Thixotropic yield-stress fluids (TYSFs) are a unique class of materials whose properties are affected by both shear rate and shear history. When sheared, these materials undergo a transition from an elastic solid to a viscoelastic fluid, which is accompanied by a structural transition that slowly recovers upon the cessation of shear. The strong interdependence between structure, dynamics, and rheological properties in TYSFs make it challenging to identify the fundamental physics controlling these phenomena. In this study, we vary the ionic strength of a suspension of cellulose nanocrystals (CNC) to generate model TYSFs with tunable moduli and thixotropic kinetics. We use a novel rheological protocol—serial creep divergence—to identify the physics underlying the yield transition and recovery of CNC gels. Our protocol identifies a critical transition that bifurcates the solid-like and fluid-like regimes of the gels to precisely determine the yield stress of these materials even in the presence of thixotropic effects. Additionally, the thixotropic kinetics collapse onto a single master curve, which we fit to a transient solution to a coupled diffusion–aggregation model. Our work thereby identifies the underlying physicochemical mechanisms driving yielding and thixotropic recovery in attractive colloidal gels. [ABSTRACT FROM AUTHOR]

Therapeutic deep eutectic solvents (THEDES) are an emerging family of eutectic mixtures gaining increasing interest in the biomedical space. The immobilization of THEDES into polymer networks allows bioactive eutectogels to expand their application scope to topical drug delivery. Herein, this work presents the first set of elastomeric eutectogels constructed by supporting a therapeutic eutectic system with skin permeation ability in a protein scaffold dynamically crosslinked by a natural polyphenol. In this ionic eutectic, gelatin undergoes gelation through an unexpected mechanism in striking contrast with classical hydrogels, which is herein thoroughly studied. Interestingly, the polyphenol controls the conformation of the protein structure, enabling tuning up the mechanical and viscoelastic behavior of the dynamic eutectogel networks from elastic to hyperelastic. The resultant protein eutectogels exhibit strain‐hardening behavior, thermoreversible gel‐to‐sol transition, and excellent adhesive performance. Furthermore, these versatile materials retain the bioactivity of the liquid THEDES and favor skin occlusion, assisting the delivery of both hydrophilic and hydrophobic substances in ex vivo porcine skin in a time‐dependent penetration process. These ultrastretchable eutectogels show new interplays between protein scaffolds and eutectic mixtures, paving the way for innovative therapeutic soft materials. [ABSTRACT FROM AUTHOR]

Sol-Gel is formed by conversion of liquid precursor into a sol and then to a gel. This technique is a common process for forming porous materials via solidification from a real solution phase. Preparation of homogenous solution, hydrolysis, gelation, drying, densification are major steps in sol-gel formation. Sol-Gel derived materials include glasses, ceramics, and nanoparticles, each offering unique properties and characteristics tailored to particular applications. Sol-Gel offers a distinct pathway for creation of many new and conventional nanomaterials that had been improved by combustion or hydrothermal treatment. This review highlights sol-gel process, steps involved in preparation and applications in medicine. [ABSTRACT FROM AUTHOR]

The ancestral method of preparing chuño (freeze‐dried potato) involves three steps: freezing, soaking, and drying. The objective of this study is to identify the changes in microstructure, in physicochemical properties, and rheology of gels and suspensions of Andean potato starches caused by the procedure used to obtain chuño. A laboratory simulation of the procedure is performed using the potato variety "Rosadita" (Solanum tuberosum ssp. Andigenum). From the tests carried out on the starches extracted from the chuño obtained in the field and in the laboratory, differences phosphate content and gelatinization temperature are found. Marked differences are observed with respect to the control starch in the soluble amylose content, RVA profiles, textural attributes, and dynamic and viscous rheological properties. The chuño starches present greater resistance to granular breakdown. These observations suggest a different hydration, swelling, and gelation mechanism for the Rosadita and chuño starch samples compared to conventional potato starch and at the same time a modification due to the effect of freezing, which is more noticeable in the chuño obtained at −5 °C. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is a versatile polymer with many applications in a wide range of products. A novel 3D printing technology called liquid additive manufacturing (LAM) extended its possibilities by generating PU elastomers with gradient properties in continuous processing. LAM, being a relatively new technique, has not been extensively researched, particularly in terms of the curing behavior of the liquid resin. In this work, we investigated the effect of composition on gelation time tGP as measured by time-resolved mechanical spectroscopy (TRMS) and analyzed using the Winter–Chambon criterion with the assistance of the IRIS software. This method is more accurate than the previous approach, which involved time sweeps with a constant frequency. It was found that the gel time tGP first decreased and then increased with increasing polyol ratio, ranging from 231 to 378 min. Furthermore, the crosslink densities of the different PU elastomers measured from the rheological and tensile tests were calculated and compared based on the theory of rubber elasticity. The crosslink density decreased with an increasing polyol ratio in both methods. However, the crosslink density values obtained from the rheological measurements were higher than those from the tensile tests. These findings demonstrate that adjusting the polyol ratio is an effective means of achieving gradient properties. The composition effects we measured offer valuable insights for the design of LAM–PU elastomers. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hairtail (Trichiurus haumela) surimi exhibits poor gelation properties and a dark gray appearance, which hinder its utilization in high‐quality surimi gel products. The effect of Pickering emulsions stabilized by myofibrillar proteins (MPE) on the gel properties of hairtail surimi has been unclear. In particular, the impact of MPE under NaCl and KCl treatments on the quality of hairtail surimi gels requires further elucidation. RESULTS: Pickering emulsions stabilized by myofibrillar proteins and treated with NaCl or KCl (Na‐MPE, K‐MPE) were added to hairtail surimi in amounts of 10–70 g kg−1. The addition of 50 g kg−1 Na‐MPE and K‐MPE improved the gel strength, textural properties, whiteness, and water‐holding capacity (WHC) of hairtail surimi. The relative content of β‐turn and β‐sheet in the surimi gels increased and the relative content of random coils and α‐helix decreased with the addition of oil. The addition of Na‐MPE and K‐MPE did not affect the secondary structure of surimi gels but stimulated the gelation of hairtail surimi gels. Hairtail surimi containing K‐MPE demonstrated similar performance in terms of hardness, microstructure, and WHC compared with the addition of Na‐MPE. CONCLUSION: The quality of hairtail surimi gels can be improved by the addition of Na‐MPE or K‐MPE. The K‐MPE proved to be an effective option for enhancing the properties of hairtail surimi gels at 50 g kg−1 to replace Na‐MPE. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Understanding mechanisms of myofibrillar protein gelation is important for development of gel-type muscle foods. The protein-protein interactions are largely responsible for the heat-induced gelation. Exogenous additives have been extensively applied to improve gelling properties of myofibrillar proteins. Research has been carried out to investigate effects of different additives on protein gelation, among which low molecular substances as one of the most abundant additives have been recently implicated in the modifications of intermolecular interactions. In this review, the processes of myosin dissociation under salt and the subsequent interaction via intermolecular forces are elaborated. The underlying mechanisms focusing on the role of low molecular additives in myofibrillar protein interactions during gelation particularly in relation to modifications of the intermolecular forces are comprehensively discussed, and six different additives i.e. metal ions, phosphates, amino acids, hydrolysates, phenols and edible oils are involved. The promoting effect of low molecular additives on protein interactions is highly attributed to the strengthened hydrophobic interactions providing explanations for improved gelation. Other intermolecular forces i.e. covalent bonds, ionic and hydrogen bonds could also be influenced depending on varieties of additives. This review can hopefully be used as a reference for the development of gel-type muscle foods in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] Colloidal suspensions of anisotropic particles are ubiquitous in particle-based industries. Consequently, there is a need to quantify the effects of particle shape on equilibrium phases and kinetic state transitions, particularly at lower aspect ratios (L / D ≈ 1–10). We present a new, colloidal system comprised of hollow, octadecyl-coated silica rods with 40 nm diameter with controlled aspect ratio and thermoreversible short-range attractions. Rheology and dynamic light scattering measurements on suspensions of these hollow adhesive hard rods with nominal aspect ratio ≈3 suspended in tetradecane exhibit thermoreversible gelation without complicating effects of gravitational settling. Small angle neutron scattering measurements of the microstructure are analyzed to determine the effective strength of attraction in the form of Baxter sticky parameter. Quantitative agreement is found with simulation predictions of the thermoreversible gel transition as a function of volume fraction, further validating a universal state diagram and providing guidance for the effects of aspect ratio on gelation. [ABSTRACT FROM AUTHOR]

Collagen-based hydrogels have been widely used as biomaterials in recent years owing to their excellent biological properties. However, their poor mechanical properties due to the poor solubility of native collagen under physiological conditions limit their application. In this case, although the solubility of collagen can be improved by succinylation, the gelation of succinylated collagen (SCol) is another challenge. Herein, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) was used to induce the gelation of SCol based on the formation of anhydride bonds between the carboxyl groups of SCol. The concentration of the SCol system was increased to 30.0 mg mL−1, which was much higher than that of the collagen system (10 mg mL−1). Correspondingly, the elastic modulus (G′) of SCol hydrogels was improved to 310 Pa, which was higher than that of the collagen hydrogel (20 Pa). Notably, the triple helix of SCol is crucial for its EDC-induced gelation. The transmittance, porosity, and water content of the SCol hydrogel were studied. Additionally, the cytocompatibility of the SCol hydrogel was explored using CCK8 colorimetry and confocal microscopy. This study provides a novel strategy for improving the mechanical properties of hydrogels by increasing collagen concentration, which is helpful for the design and application of collagen-based materials. [ABSTRACT FROM AUTHOR]

An ideal hydrogel for stem cell therapy would be injectable and efficiently promote stem cell proliferation and differentiation in body. Herein, an injectable, single‐component hydrogel with hyaluronic acid (HA) modified with phenylboronic acid (PBA) and spermidine (SM) is introduced. The resulting HAps (HA‐PBA‐SM) hydrogel is based on the reversible crosslinking between the diol and the ionized PBA, which is stabilized by the SM. It has a shear‐thinning property, enabling its injection through a syringe to form a stable hydrogel inside the body. In addition, HAps hydrogel undergoes a post‐injection "self‐curing," which stiffens the hydrogel over time. This property allows the HAps hydrogel to meet the physical requirements for stem cell therapy in rigid tissues, such as bone, while maintaining injectability. The hydrogel enabled favorable proliferation of human mesenchymal stem cells (hMSCs) and promoted their differentiation and mineralization. After the injection of hMSCs‐containing HAps into a rat femoral defect model, efficient osteogenic differentiation of hMSCs and bone regeneration is observed. The study demonstrates that simple cationic modification of PBA‐based hydrogel enabled efficient gelation with shear‐thinning and self‐curing properties, and it would be highly useful for stem cell therapy and in vivo bone regeneration. [ABSTRACT FROM AUTHOR]

This study investigated the properties of starch isolated from the unripe fruit of two apple cultivars (Malus domestica Borkh) grown in southern Poland (Central Europe). The chemical composition of both starches, molecular mass, their granulation, thermal characteristics, swelling characteristics, and rheological characteristics were studied. The starches differed significantly in ash, phosphorus, and protein content. The water-binding capacity at temperatures of 25–65 °C was similar, while differences of 20% appeared at higher temperatures. In contrast, a significant difference was found in the solubility of the two starches in the temperature range of 25–75 °C. The study showed that apple starches have a relatively low tendency to retrograde, with the enthalpy of gelatinization for starch from the Oliwka variety being 40% higher than that from the Pyros variety. However, the starches differed in the hardness of the gels formed, i.e., one variety formed soft gels with an internal structure resistant to external forces, while the other formed hard gels. [ABSTRACT FROM AUTHOR]

Mimicking tissue‐oriented organization in vitro has been extensively studied in recent years, using both natural and synthetic materials in combination with external magnetic fields to establish anisotropic conditions. Here, a new combination between magneto‐responsive anisometric PEG microgels and collagen hydrogels is explored to establish anisotropic in vitro models. Different sizes of PEG microgels are tested to assess the impact of both width and aspect ratio on the formation and alignment of collagen hydrogels. Results show that the key properties of collagen hydrogels, regarding fibrillogenesis, rheological properties, and fiber diameter are kept consistent upon the combination with PEG microgels. Furthermore, partial collagen fiber alignment is observed when larger (width 10 µm) PEG microgels are employed and magnetically aligned. In vitro studies show cell alignment within the anisotropic collagen hydrogels from the first day in culture. Interestingly, PEG microgels with higher width and length tend to induce less hydrogel contraction even after 7 days in culture. The results demonstrate the ability to establish a 3D unidirectional collagen hydrogel by magnetically aligning anisometric microgels during the gelation process, which can be promising for different tissue engineering applications. [ABSTRACT FROM AUTHOR]

Heating is a vital step in the gelation of surimi. Conventional water bath heating (WB) has the advantages of easy operation and low equipment requirements. However, the slow heat penetration during WB may lead to poor gel formation or gels prone to deterioration, especially with one-step heating. The two-step WB is time-consuming, and a large amount of water used tends to cause environmental problems. This review focuses on key factors affecting the quality of surimi gels in various heating technologies, such as surimi protein structure, chemical forces, or the activity of endogenous enzymes. In addition, the relationships between these factors and the gel performance of surimi under various heating modes are discussed by analyzing the heating temperature and heating rate. Compared with WB, the gel performance can be improved by controlling the heating conditions of microwave heating and ohmic heating, which are mainly achieved by changing the molecular structure of myofibrillar proteins or the activity of endogenous enzymes in surimi. Nevertheless, the novel thermal technologies still face several limitations and further research is needed to realize large-scale industrial production. This review provides ideas and directions for developing heat-induced surimi products with excellent gel properties. [ABSTRACT FROM AUTHOR]

Based on the in-situ bimetallic co-gelation process, the high dispersion of Cu in the Cu/Fe 3 O 4 -BMMA was realized, providing conditions for the efficient elimination of I 2. The adsorption experiments showed that Cu/Fe 3 O 4 -BMMA has good I 2 adsorption capacity (631.3 mg/g) and fast capture kinetics (equilibrium time <30 min). In addition, Cu/Fe 3 O 4 -BMMA was able to effectively remove trace I 2 in the solution from ppm level (1.0 ppm) down to ppb level (≤30 ppb). The adsorbed I 2 was converted into stable CuI, avoiding secondary pollution due to desorption. Notably, the used Cu/Fe 3 O 4 -BMMA was able to be separated from the solution by simple magnetic suction, which greatly improved the efficiency and reduced the recovery cost. Overall, this study provides a potentially efficient iodine capture material for long-term decay storage of radioactive iodine. [Display omitted] • The Cu in Cu/Fe 3 O 4 -BMMA exhibited high reactivity and utilization. • Cu/Fe 3 O 4 -BMMA can effectively reduce I 2 and adsorb it to generate stable CuI. • Cu/Fe 3 O 4 -BMMA exhibited a high removal rate of trace I 2 in actual environments. • The used adsorbents can be rapidly recovered by magnetic adsorption. Adsorption is considered to be one of the most effective methods to remove radioiodine from the solution. However, developing highly efficient adsorbents and the rapid recovery of the used adsorbents is still a challenge. Here, a series of Cu/Fe 3 O 4 bimetallic mutual-doping magnetic aerogels (Cu/Fe 3 O 4 -BMMA) were synthesized. Based on the in-situ bimetallic co-gelation process, the high dispersion of Cu in the aerogel was realized, providing conditions for the efficient elimination of I 2. The Fe3+ in the initial gel was reduced to magnetic Fe 3 O 4 during the preparation process, allowing for the quick recovery of the adsorbent through the application of a magnetic field. The adsorption experiments showed that Cu/Fe 3 O 4 -BMMA has good I 2 adsorption capacity (631.3 mg/g) and fast capture kinetics (equilibrium time < 30 min). In addition, Cu/Fe 3 O 4 -BMMA was able to effectively remove trace I 2 in the solution from ppm level (1.0 ppm) down to ppb level (≤30 ppb). The adsorbed I 2 was converted into stable CuI, avoiding secondary pollution due to desorption. Overall, this study provides a potentially efficient iodine capture material for long-term decay storage of radioactive iodine. [ABSTRACT FROM AUTHOR]

We demonstrate supramolecular polymerization and formation of 1D nanofiber of azobenzene based organogelator (AZO‐4) in cyclic hydrocarbon solvents (toluene and methylcyclohexane). The AZO‐4 exhibits J‐ and H‐type aggregates in toluene: MCH (9 : 1) and MCH: toluene (9 : 1) respectively. The type of aggregate was governed by the geometry of the solvents used in the self‐assembly process. The J‐type aggregates with high thermal stability in toluene is due to the enhanced interaction of AZO‐4 π‐ surface with the toluene π‐surface, whereas H‐aggregate with moderate thermal stability in MCH was due to the interruption of the cyclic hydrocarbon in van der Waals interactions of peripheral chains of AZO‐4 molecule. The light induced reversible photoisomerization is observed for both J‐ and H‐aggregates. The macroscopic property revealed spontaneous and strong gelation in toluene preferably due to the strong interactions of the AZO‐4 nanofibers with the toluene solvent molecules compared to the MCH. The rheological measurements revealed thixotropic nature of the gels by step‐strain experiments at room temperature. The thermodynamic parameter (ΔHm) of gel‐to‐sol transition was determined for all the gels to get more insight into the gelation property. Furthermore, the phase selective gelation property was extended to the oil spill recovery application using diesel/water and petrol/water mixture. [ABSTRACT FROM AUTHOR]

AbstractMolybdenum disulfide (MoS2), a two-dimensional inorganic molecule, has lately been studied in medical research with regard to carrying pharmaceuticals due to its distinctive characteristics. A biodegradable polymer system applicable in cancer drug delivery can be created with the addition of MoS2. In our research described in this paper, we investigated the influence of the amount of MoS2 on the characteristics and performance of our novel gel blend. It was aimed to prepare a new gel blend, which we thought would have the potential to be used as a stimulus-sensitive, polymeric hydrogel as a carrier in the triple negative breast cancer (TNBC) drug delivery system, with the MoS2 added to the polyethylene glycol (PEG)/κ-carrageenan combination. This 2D material (MoS2) impacted the hydrogel by improving the transmittance, swelling, and elasticity performance compared to the normal no MoS2 structure of the polymeric gel. The polymer blend characteristics were mainly tested using UV-VIS spectrophotometry and gravimetric analysis. The varied properties of these gel mixtures were investigated using five different mass ratios of MoS2. The 5 mg MoS2/(PEG)/κ-carrageenan gel was the best sample investigated in terms of the elasticity. The results of the study demonstrated that our gel system can be utilized for precisely targeted and regulated delivery of cancer drugs. To create preliminary data for this near future goal, the release mechanism of the Doxorubicin drug loaded into the produced gel were examined. [ABSTRACT FROM AUTHOR]

Flexible intelligent actuators with the characteristics of flexibility, safety and scalability, are highly promising in industrial production, biomedical fields, environmental monitoring, and soft robots. Nanocomposite hydrogels are attractive candidates for soft actuators due to their high pliability, intelligent responsiveness, and capability to execute large‐scale rapid reversible deformations under external stimuli. Here, the recent advances of nanocomposite hydrogels as soft actuators are reviewed and focus is on the construction of elaborate and programmable structures by the assembly of nano‐objects in the hydrogel matrix. With the help of inducing the gradient or oriented distributions of the nanounits during the gelation process by the external forces or molecular interactions, nanocomposite hydrogels with ordered structures are achieved, which can perform bending, spiraling, patterned deformations, and biomimetic complex shape changes. Given great advantages of these intricate yet programmable shape‐morphing, nanocomposite hydrogel actuators have presented high potentials in the fields of moving robots, energy collectors, and biomedicines. In the end, the challenges and future perspectives of this emerging field of nanocomposite hydrogel actuators are proposed. [ABSTRACT FROM AUTHOR]

Fish gelatin (FG)-based wound dressings exhibit superior water absorption capacity, thermal stability, and gelation properties, which enhance the performance of these dressings. In this study, our objective was to investigate the conditions underlying the enzymatic hydrolysis of FG and subsequent cross-linking to prepare high-performance gels. A two-step enzymatic method of protease-catalyzed hydrolysis followed by glutamine transglutaminase (TGase)-catalyzed cross-linking was used to prepare novel high-performance fish gelatin derivatives with more stable dispersion characteristics than those of natural gelatin derivatives. Compared with conventional TGase cross-linked derivatives, the novel derivatives were characterized by an average pore size of 150 μm and increased water solubility (423.06% to 915.55%), water retention (by 3.6-fold to 43.89%), thermal stability (from 313 °C to 323 °C), and water vapor transmission rate, which reached 486.72 g·m−2·24 h−1. In addition, loading glucose oxidase onto the fish gelatin derivatives increased their antibacterial efficacy to >99% against Escherichia coli and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

BACKGROUND: Laboratory scale experiments have shown that curdlan and gellan gum gelled together as curdlan/gellan gum (CG) hybrid gels showed better gel properties than the individual curdlan and gellan gum. In this study, CG and black wolfberry anthocyanin (BWA), CG and maltitol (ML) hybrid gels were constructed using CG hybrid gel as matrix. The effects of BWA or ML on the gel properties and microstructure of CG hybrid gels were investigated and a confectionery gel was developed. RESULTS: The presence of BWA increased the storage modulus (G') value of CG at 0.1 Hz, whereas ML had little effect on the G' value of CG. The addition of BWA (5 g L−1) and ML (0.3 mol L−1) increased the melting and gelling temperatures of CG hybrid gels to 42.4 °C and 34.1 °C and 44.2 °C and 33.2 °C, respectively. Meanwhile, the relaxation time T22 in CG‐ML and CG‐BWA hybrid gels was reduced to 91.96 and 410.27 ms, indicating the strong binding between BWA and CG, ML and CG. The hydrogen bond interaction between BWA or ML and CG was confirmed by the shift in the hydroxyl stretching vibration peak. Moreover, the microstructures of CG‐ML and CG‐BWA hybrid gels were denser than that of CG. In addition, confectionery gel containing CG‐BWA‐ML has good chewing properties. CONCLUSION: These results indicated that the incorporation of BWA or ML could improve the structure of CG hybrid gels and assign a sustainability potential for the development of confectionery gels based on CG complex. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In the cheese industry, whey, which is rich in lactose and proteins, is underutilized, causing adverse environmental impacts. The fractionation of its components, typically carried out through filtration membranes, faces operational challenges such as membrane fouling, significant protein loss during the process, and extended operating times. These challenges require attention and specific methods for optimization and to increase efficiency. A promising strategy to enhance industry efficiency and sustainability is the use of enzymatic pre‐treatment with the enzyme transglutaminase (TGase). This enzyme plays a crucial role in protein modification, catalyzing covalent cross‐links between lysine and glutamine residues, increasing the molecular weight of proteins, facilitating their retention on membranes, and contributing to the improvement of the quality of the final products. The aim of this study is to review the application of the enzyme TGase as a pretreatment in whey protein filtration. The scope involves assessing the enzyme's impact on whey protein properties and its relationship with process performance. It also aims to identify both the optimization of operational parameters and the enhancement of product characteristics. This study demonstrates that the application of TGase leads to improved performance in protein concentration, lactose permeation, and permeate flux rate during the filtration process. It also has the capacity to enhance protein solubility, viscosity, thermal stability, and protein gelation in whey. In this context, it is relevant for enhancing the characteristics of whey, thereby contributing to the production of higher quality final products in the food industry. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

By using different salts as a method to achieve gelation of two different amino-acid-functionalised perylene bisimides, we were able to tune reduction potentials while maintaining the mechanical and optical properties of the system all at pH 7.4. [ABSTRACT FROM AUTHOR]

AbstractThe phase state of Cu2+ complexes with acrylamide and sodium acrylate copolymers at different copolymer concentrations and components molar ratios was studied. The change in complex stoichiometry from 2 to 3 carboxylate groups per Cu2+ ion was detected with an increase of copolymer concentration. In the concentrated solutions of copolymers, gelation is observed upon addition of Cu2+ ions, with the lowest concentration of copper required for gelation decreasing with the increase in copolymer concentration. These hydrogels are attributed to the formation of meta-stable inter-polymer metal complexes, which are able to persist due to a low segment mobility. The phase separation of complexes is shown to be associated with the bidentate coordination of carboxylate groups to Cu2+ ions, while the hydrogels formed in concentrated solutions mostly consist of bridging structures. Gelation threshold corresponds to the second critical concentration of poly(acrylamide-co-sodium acrylate) and is lower for copolymers with the higher molecular weight. Low acrylate content in the copolymers prevents collapse of the hydrogels caused by the salting-out effect. A higher gel content can be reached by increasing the copolymer concentration or the molar ratio of copper ions to carboxylate groups, with the latter reducing the swelling degree. [ABSTRACT FROM AUTHOR]

The gelation kinetics of agar aqueous solutions were studied by means of the viscosity flow curves using a coaxial Couette cylinder viscometer. The viscosity curves show an unusual sigmoidal trend or an exponential decay to a viscous steady state. An original theory of gelation kinetics was developed considering the coarsening of increasingly larger and more stable clusters due to Ostwald ripening and the breakup of clusters that were too large due to the instability of rotating large particles induced by the shear rate. The developed Bounded Ripening Growth model takes into account the trend of the viscosity curves by means of an autocatalytic process with negative feedback on aggregation according to the logistic kinetic equation, in which the constants  k 1 (γ)  and  k − (ν)  are governed by the surface tension and shear rate, respectively. A dimensionless equation based on the difference between the Weber number and the ratio of the inverse kinetic constant to forward constant, accounts for the behavior of the dispersed phase in equilibrium conditions or far from the hydrostatic equilibrium. [ABSTRACT FROM AUTHOR]

Polysilsesquioxane (PSQ) microspheres have shown promise in many fields, but previous studies about porous PSQ microspheres are scarce. Herein, we fabricated novel micron-sized thiol-functional polysilsesquioxane (TMPSQ) microspheres with open and interconnected macropores by combining inverse suspension polymerization with two-step sol–gel and polymerization-induced phase separation processes, without using phase-separation-promoting additives or sacrificial templates. The chemical composition of the TMPSQ microspheres was confirmed using FTIR and Raman spectroscopy. The morphology of the TMPSQ microspheres was characterized using SEM and TEM. TGA was employed to test the thermal stability of the TMPSQ microspheres. Mercury intrusion porosimetry and nitrogen adsorption–desorption tests were performed to investigate the pore structure of the TMPSQ microspheres. The results showed that the TMPSQ microspheres had open and interconnected macropores with a pore size of 839 nm, and the total porosity and intraparticle porosity reached 70.54% and 43.21%, respectively. The mechanism of porous generation was proposed based on the morphological evolution observed using optical microscopy. The macropores were formed through the following four steps: phase separation (spinodal decomposition), coarsening, gelation, and evaporation of the solvent. The macropores can facilitate the rapid mass transfer between the outer and inner spaces of the TMPSQ microspheres. The TMPSQ microspheres are promising in various fields, such as catalyst supports and adsorbents. [ABSTRACT FROM AUTHOR]

1. Theoretical calculation confirmed the heterostructure of Mo 2 C-MoP exhibits moderate adsorption energies with LiPSs, which benefits for the conversion of LiPSs. 2. The Mo 2 C trigger the ring-opening polymerization of the DOL solvent to generate a surface gel layer. The gel layer covers the surface of the Mo 2 C electrocatalyst and renders reduced electrocatalytic activity. 3. The introducing of MoP can avoid the surface gelation of the catalyst, and thus improved the performance of the catalyst in the actual battery. [Display omitted] The cathodic polysulfides electrocatalyst, such as Mo 2 C, offers a promising approach to mitigate the shuttling effect by providing strong polysulfide adsorption and catalyst abilities to improve the electrochemical performance of Lithium-sulfur (Li-S) batteries. However, according to the Sabatier principle, excessive adsorption of Mo 2 C undermines the conversion of polysulfides. This undesirable effect can be mitigated by forming the heterostructure of Mo 2 C-MoP. Even more importantly, the introduction of MoP can prevent the surface gelation of Mo 2 C and expose more active sites. Consequently, the Li-S batteries with the Mo 2 C-MoP sulfur host exhibit outstanding long-term cycling stability, showcasing a mere 0.035% capacity decay per cycle over 800 cycles at 1 C. This work on the balance between adsorption capacity and catalytic active of cathodic polysulfides electrocatalyst provides a new vision for realizing a high-performance Li-S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Aqueous suspensions of cellulose nanocrystals (CNC) form a re-entrant liquid crystal (LC) phase with increasing salinity. Phase separation occurs in this LC state leading to a biphasic gel with a flow programmable structure that can be used to form anisotropic soft materials. We term this state a Liquid Crystal Hydroglass (LCH). Defining the mechanisms by which the LCH forms requires detailed structural analysis at the mesoscopic length scale. By utilising Small Angle Neutron Scattering (SANS), we investigated the microstructure transitions in CNC suspensions, with a particular focus on the unique LC re-entrancy and gelation into the biphasic LCH. Scattering from LCH gels comprises contributions from a dispersed liquid state and static heterogeneity, characterised using a Lorentzian-Gaussian model of inhomogeneity. This conceptually supports a gelation mechanism (spinodal decomposition) in CNC suspensions towards a biphasic structure of the LCH. It also demonstrates that, with increasing salinity, the non-monotonic variation in effective volume fraction of CNC rods fundamentally causes the LC re-entrancy. This work provides the first experimental characterisation of the LC-re-entrancy and formation of an anisotropic LCH gel. The proposed mechanism can be extended to understanding the general behaviour of anisotropic colloids. [ABSTRACT FROM AUTHOR]

[Display omitted] • By incorporating MXene nanosheets and Fe3+ into the hydrogel network, rapid gelation (within 10 s) was achieved. • This dual-network conductive hydrogel composite exhibited outstanding stretchability, extremely low energy dissipation. • This work provides a feasible platform for developing integrated wearable health-monitoring electronic systems. Hydrogel-based functional materials had attracted great attention in the fields of artificial intelligence, soft robotics, and motion monitoring. However, the gelation of hydrogels induced by free radical polymerization typically required heating, light exposure, and other conditions, limiting their practical applications and development in real-life scenarios. In this study, a simple and direct method was proposed to achieve rapid gelation at room temperature by incorporating reductive MXene sheets in conjunction with metal ions into the chitosan network and inducing the formation of a polyacrylamide network in an extremely short time (10 s). This resulted in a dual-network MXene-crosslinked conductive hydrogel composite that exhibited exceptional stretchability (1350 %), remarkably low dissipated energy (0.40 kJ m−3 at 100 % strain), high sensitivity (GF = 2.86 at 300–500 % strain), and strong adhesion to various substrate surfaces. The study demonstrated potential applications in the reliable detection of various motions, including repetitive fine movements and large-scale human body motions. This work provided a feasible platform for developing integrated wearable health-monitoring electronic systems. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Salted hen egg yolks are less oily and less flavorful than salted duck egg yolks. However, hen eggs have a more adequate market supply and have a broader application prospect than duck eggs. In the present study, egg yolks, plasma, and granules were dehydrated by adding 1% NaCl to simulate traditional curing process of salted egg yolk. The changes in the pickling process of hen egg yolks (HEY) and duck egg yolks (DEY) plasma and granules were compared to reveal the gelation mechanism and the underlying causes of quality differences in salted HEY and DEY. Salted HEY can be compared with the changes in DEY during the pickling process to provide a theoretical basis for the quality improvement of salted HEY to salted DEY.The results showed that both plasma and granules were involved in gel formation, but exhibited different aggregation behaviors. Based on the intermolecular forces, the HEY proteins achieved aggregation mainly through hydrophobic interactions and DEY proteins mainly through covalent binding. According to spin–spin relaxation time, HEY gels immobilized a large amount of lipid and interacted strongly with lipids. DEY gels showed much free lipid and had weak interaction with lipid. The microstructure showed that HEY proteins were easily unfolded to form a homogeneous three‐dimensional gel network structure after salting, whereas heterogeneous aggregates were formed to hinder the gel development in DEY. Changes in protein secondary structure content showed that pickling can promote the transformation of the α‐helices to β‐sheets structure in HEY gels, whereas more α‐helices structure was formed in DEY gels.The present study has demonstrated that different gelation behaviors of hen and duck egg yolk proteins (especially in plasma) through salting treatment led to the difference in the quality of salted HEY and DEY. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Hydrogels with injectability have emerged as the focal point in tissue filling, owing to their unique properties, such as minimal adverse effects, faster recovery, good results, and negligible disruption to daily activities. These hydrogels could attain their injectability through chemical covalent crosslinking, physical crosslinking, or biological crosslinking. These reactions allow for the formation of reversible bonds or delayed gelatinization, ensuring a minimally invasive approach for tissue filling. Injectable hydrogels facilitate tissue augmentation and tissue regeneration by offering slow degradation, mechanical support, and the modulation of biological functions in host cells. This review summarizes the recent advancements in synthetic strategies for injectable hydrogels and introduces their application in tissue filling. Ultimately, we discuss the prospects and prevailing challenges in developing optimal injectable hydrogels for tissue augmentation, aiming to chart a course for future investigations. [ABSTRACT FROM AUTHOR]

Alginate is a natural biopolymer widely studied for pharmaceutical applications due to its biocompatibility, low toxicity, and mild gelation abilities. This review summarizes recent advances in alginate-based encapsulation systems for targeted drug delivery. Alginate formulations like microparticles, nanoparticles, microgels, and composites fabricated by methods including ionic gelation, emulsification, spray drying, and freeze drying enable tailored drug loading, enhanced stability, and sustained release kinetics. Alginate microspheres prepared by spray drying or ionic gelation provide gastric protection and colon-targeted release of orally delivered drugs. Alginate nanoparticles exhibit enhanced cellular uptake and tumor-targeting capabilities through the enhanced permeation and retention effect. Crosslinked alginate microgels allow high drug loading and controlled release profiles. Composite alginate gels with cellulose, chitosan, or inorganic nanomaterials display improved mechanical properties, mucoadhesion, and tunable release kinetics. Alginate-based wound dressings containing antimicrobial nanoparticles promote healing of burns and chronic wounds through sustained topical delivery. Although alginate is well-established as a pharmaceutical excipient, more extensive in vivo testing is needed to assess clinical safety and efficacy of emerging formulations prior to human trials. Future opportunities include engineered systems combining stimuli-responsiveness, active targeting, and diagnostic capabilities. In summary, this review discusses recent advances in alginate encapsulation techniques for oral, transdermal, and intravenous delivery, with an emphasis on approaches enabling targeted and sustained drug release for enhanced therapeutic outcomes. [ABSTRACT FROM AUTHOR]

The rheological characteristics of high-pour-point (high-PPT) oil are crucial for its economical and safe production and transportation. However, current research on the viscosity–temperature prediction and viscoelastic-yielding transition of high-PPT oil is insufficient. The Arrhenius formula faces challenges in accurately depicting the viscosity–temperature relationship, and there is a lack of a quantitative description of the viscoelastic-yielding transition behavior in gelled high-PPT oil. This study addresses these gaps through a series of rheological experiments. The results reveal that the viscosity–temperature relationship of high-PPT oil can be classified into three regions, each associated with a sequentially increasing activation energy E a . Introducing two characteristic parameters, T 0 and n , yields a modified Arrhenius formula with an extended range of applicability. Thixotropy and gelation process experiments demonstrate an exponential increase in thixotropic strength with a decreasing temperature below the wax appearance temperature, while an optimum cooling rate maximizes the gelation degree of high-PPT oil. A brittleness index B I was defined to quantitatively describe the fracture mode of gelled crude. Critical characteristic strains and B I exhibit a decrease with an increase in the reciprocal of the average free degree 1 / w free , where the diminishing trend of B I follows a robust power-law form. This comprehensive investigation contributes valuable insights into the rheological behavior of high-PPT oil, offering a foundation for more accurate modeling and control strategies in its production and transportation. [ABSTRACT FROM AUTHOR]

Bipyridine‐based gelator 1 having two D‐alanine units was prepared, and its gelation ability was evaluated in the presence of Co(NO3)2 and AgNO3 in water. Gelator 1 could gelate H2O in the presence of Co(NO3)2 or AgNO3 (1.0 equiv.) in water. Gelator 1 formed a 2:1 (1:Co2+) octahedral complex with Co2+, whereas it formed a 2:1 (1:Ag+) tetrahedral complex with Ag+. The metallosupramolecular hydrogel with Co2+ assembled into a left‐handed helical fiber, whereas that with Ag+ assembled into a nanorod structure. 1H NMR and FTIR analyses revealed that π–π stacking and intermolecular hydrogen bonds acted as the driving force for the formation of the supramolecular nanoarchitectures. Furthermore, to characterize the viscoelastic properties of hydrogels, rheology experiments were conducted at 25°C, including time, strain, and frequency sweeps. [ABSTRACT FROM AUTHOR]

Rugulopteryx okamurae (RO) is an invasive brown seaweed that causes severe environmental problems in the Mediterranean Sea. This work proposed an extraction method that enables their use as a raw material for producing sodium alginate. Alginate was successfully extracted from this invasive seaweed, with its gelling performance in the presence of Ca2+ ions comparable to existing commercial alginates. The mannuronic acid (M)-to-guluronic (G) acid ratio in the 1H-NMR profile indicated a higher percentage of G in the RO-extracted alginate, which implies a greater formation of so-called egg box structures. These differences resulted in their different rheological behaviour, as sodium alginate aqueous solutions exhibited a greater viscosity ( η at 1 s−1 = 3.8 ± 0.052 Pa·s) than commercial alginate (2.8 ± 0.024 Pa·s), which is related to the egg box structure developed. When gelled in the presence of calcium, an increase in the value of the elastic modulus was observed. However, the value of the tan δ for the extracted alginate was lower than that of commercial alginate gels, confirming a structure more densely packed, which implies a different restructuring of the alginate chain when gelling. These results confirm the suitability of using invasive Rugulopteryx okamurae as a source of calcium alginate gels. In this way, sustainable bio-based materials may be produced from undesired biomass that currently poses a threat to the ecosystem. [ABSTRACT FROM AUTHOR]

We investigate the thermal gelation of egg white proteins at different temperatures with varying salt concentrations using x-ray photon correlation spectroscopy in the geometry of ultra-small angle x-ray scattering. Temperature-dependent structural investigation suggests a faster network formation with increasing temperature, and the gel adopts a more compact network, which is inconsistent with the conventional understanding of thermal aggregation. The resulting gel network shows a fractal dimension δ, ranging from 1.5 to 2.2. The values of δ display a non-monotonic behavior with increasing amount of salt. The corresponding dynamics in the q range of 0.002–0.1 nm−1 is observable after major change of the gel structure. The extracted relaxation time exhibits a two-step power law growth in dynamics as a function of waiting time. In the first regime, the dynamics is associated with structural growth, whereas the second regime is associated with the aging of the gel, which is directly linked with its compactness, as quantified by the fractal dimension. The gel dynamics is characterized by a compressed exponential relaxation with a ballistic-type of motion. The addition of salt gradually makes the early stage dynamics faster. Both gelation kinetics and microscopic dynamics show that the activation energy barrier in the system systematically decreases with increasing salt concentration. [ABSTRACT FROM AUTHOR]

We investigate the stationary flow of a colloidal gel under an inhomogeneous external shear force using adaptive Brownian dynamics simulations. The interparticle forces are derived from the Stillinger–Weber potential, where the three-body term is tuned to enable network formation and gelation in equilibrium. When subjected to the shear force field, the system develops remarkable modulations in the one-body density profile. Depending on the shear magnitude, particles accumulate either in quiescent regions or in the vicinity of maximum net flow, and we deduce this strong non-equilibrium response to be characteristic of the gel state. Studying the components of the internal force parallel and perpendicular to the flow direction reveals that the emerging flow and structure of the stationary state are driven by significant viscous and structural superadiabatic forces. Thereby, the magnitude and nature of the observed non-equilibrium phenomena differ from the corresponding behavior of simple fluids. We demonstrate that a simple power functional theory reproduces accurately the viscous force profile, giving a rationale of the complex dynamical behavior of the system. [ABSTRACT FROM AUTHOR]

A system undergoing sol–gel transition passes through a unique point, known as the critical gel state, where it forms the weakest space spanning percolated network. We investigate the nonlinear viscoelastic behavior of a colloidal dispersion at the critical gel state using large amplitude oscillatory shear rheology. The colloidal gel at the critical point is subjected to oscillatory shear flow with increasing strain amplitude at different frequencies. We observe that the first harmonic of the elastic and viscous moduli exhibits a monotonic decrease as the material undergoes a linear to nonlinear transition. We analyze the stress waveform across this transition and obtain the nonlinear moduli and viscosity as a function of frequency and strain amplitude. The analysis of the nonlinear moduli and viscosities suggests intracycle strain stiffening and intracycle shear thinning in the colloidal dispersion. Based on the insights obtained from the nonlinear analysis, we propose a potential scenario of the microstructural changes occurring in the nonlinear region. We also develop an integral model using the time-strain separable Kaye–Bernstein–Kearsley–Zapas constitutive equation with a power-law relaxation modulus and damping function obtained from experiments. The proposed model with a slight adjustment of the damping function inferred using a spectral method, compares well with experimental data at all frequencies. [ABSTRACT FROM AUTHOR]

Colloidal clay Laponite forms a variety of arrested states that display interesting aging behavior. Microrheology has been applied to Laponite-based glasses and gels, but few studies evaluate the influence of probe particle size. In this work, we report the dynamics and microrheology of Laponite-polymer dispersions during aging using passive microrheology with three different probe particle sizes. At early aging times, the neat Laponite dispersion forms an arrested state; the nature of this state (e.g., a repulsive glass or gel) has remained the subject of debate. The addition of polymer retards gelation and melts the arrested state. While this melting has been observed at the macroscale and has been attributed to a re-entrant transition of a repulsive glass to a liquid state, to our knowledge, it has not been observed at the microscale. The delay of the gelation time needed to form an arrested state was found to depend on the polymer concentration and could vary from ∼24 h for neat Laponite to seven days for some Laponite-polymer samples. Significant effects of probe particle sizes are observed from the mean-squared displacement (MSD) curves as small and intermediate probe particles show diffusive motion, while the motion of large particles is restricted. By examining the factor of ⟨Δr2 (τ)⟩a, structural heterogeneity can be confirmed through the strong size-dependence displayed. Different MSD trends of probe particles are obtained at longer aging times, but no significant changes occur after 30 days of aging. Our microrheology results also reveal significant effects of probe particle size. [ABSTRACT FROM AUTHOR]

In this work, we studied TEMPO-oxidized cellulose nanofibril (OCNF) suspensions in the presence of diverse surfactants. Using a combination of small angle neutron scattering (SANS) and rheology, we compared the physical properties of the suspensions with their structural behavior. Four surfactants were studied, all with the same hydrophobic tail length but different headgroups: hexaethylene glycol mono-n-dodecyl ether (C12EO6, nonionic), sodium dodecyl sulfate (SDS, anionic), cocamidopropyl betaine (CapB, zwitterionic), and dodecyltrimethylammonium bromide (DTAB, cationic). Contrast variation SANS studies using deuterated version of C12EO6 or SDS, or by varying the D2O/H2O ratio of the suspensions (with CapB), allowed focusing only on the structural properties of OCNFs or surfactant micelles. We showed that, in the concentration range studied, for C12EO6, although the nanofibrils are concentrated thanks to an excluded volume effect observed in SANS, the rheological properties of the suspensions are not affected. Addition of SDS or CapB induces gelation for surfactant concentrations superior to the critical micellar concentration (CMC). SANS results show that attractive interactions between OCNFs arise in the presence of these anionic or zwitterionic surfactants, hinting at depletion attraction as the main mechanism of gelation. Finally, addition of small amounts of DTAB (below the CMC) allows formation of a tough gel by adsorbing onto the OCNF surface. [ABSTRACT FROM AUTHOR]

Rare‐earth disilicates are a focus of study for use as environmental barrier coatings in gas‐turbine engines. These coatings require thermomechanical and thermochemical stability at elevated temperatures and properties can be tailored through the use of multicomponent rare‐earth disilicates. Producing rare‐earth disilicates via sol–gel is documented in literature, but there are differing procedures with varying phase purities. This work establishes trends that dictate the effects of water content, pH, and heat treatment conditions that determine the final phase purity of Yb, Er, Lu, Sc, and Y disilicate powders made via sol–gel. The phase(s) of the powders were identified and quantified using X‐ray diffraction (XRD) to extract weight fractions. In situ XRD during heating from room temperature to 1200°C was used to observe the crystallization and phase evolution of the sol–gel‐based powders, allowing for the identification of a rarely reported low temperature triclinic phase in ytterbium‐, erbium‐, and lutetium‐based disilicate sol–gels that forms prior to transformation into a monoclinic phase. Ex situ XRD allowed for the phase identification of sol–gels processed at 1400°C. These experiments demonstrated that phase‐pure disilicates could be formed under conditions with no intentional water additions, a target pH of 2, and long heat treatment times at high temperatures (e.g., 1400°C). These conditions remain valid for not only single‐cation rare‐earth disilicates of Yb, Er, Lu, Sc, and Y but also a multicomponent disilicate containing equimolar concentrations of all of these cations. [ABSTRACT FROM AUTHOR]

[Display omitted] Many lanthanide complexes do not form gel or even exhibit characteristic luminescence of lanthanide ions, which limits their applications in many fields. Therefore, there is an urgent need for a third component that can not only promote emission but also gel the lanthanide complex system to construct new smart materials such as time-dependent information encryption and anti-counterfeiting materials. Herein, a luminescent lanthanide metallogel was successfully prepared by using the third component sodium carboxymethyl cellulose (NaCMC) to induce the gelation and luminescence of the complex (H 3 L/Tb3+) of 4,4′,4″-((benzene-1,3,5-tricarbonyl)tris(azanediyl)) tris(2-hydroxybenzoic acid) (H 3 L) and Tb3+. The H 3 L/Tb3+ complex itself does not form gel and has no characteristic luminescence of Tb3+. Moreover, the multicolor emission of H 3 L/Tb3+/NaCMC gels was prepared based on Förster resonance energy transfer (FRET) platforms to obtain a high-security level information encryption and anti-counterfeiting materials. These multicolor emission gels exhibit emission color tunability with time dependence due to the different energy transfer efficiencies at each pH node controlled by glucono-δ-lactone hydrolysis time. Based on the time response characteristics, the time-dependent information encryption and anti-counterfeiting materials are developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Introducing TBA provides steric hindrance to achieve thermally induced physical crosslinking in nano-gels. • Introducing Aphe can enable the nano-gels to maintain structural color above the phase transition point. • Introducing BISS imparts redox activity to PNTA-BISS due to the disulfide bonds in the structure. • There are significant differences in the rheological properties of PNTA nano-gels when crosslinkers BAC and BISS are used. Thermally induced physical hydrogels formed through the sol–gel transition of nanogels usually lose structural color above phase transition temperature (T p). Herein, temperature/pH/redox-responsive nanogels that undergo sol–gel transition still keep structural colors above the T p have been synthesized and studied. N -isopropylacrylamide (NIPAm) was copolymerized with N - tert -butylacrylamide (TBA) and N -acrylamido- l -phenylalanine (Aphe) to form P(NIPAm/TBA/Aphe) nanogel crosslinked with N,N'-bis(acryloyl)cystine (BISS) (referred to as PNTA-BISS). PNTA-BISS nanogel with a broad range of biodegradable crosslinker BISS content can achieve a reversible sol–gel transition above the T p , surprisingly, while PNTA nanogels with a comparable content of biodegradable N,N'-Bis(acryloyl)cystam (BAC) crosslinker (referred to as PNTA-BAC) didn't form sol–gel transition. Although BISS and BAC possess same disulfide bonds with redox properties, BISS, unlike BAC, is water-soluble and features two carboxyl groups. The mechanism by which PNTA-BISS nanogels form hydrogel photonic crystals has been deeply explored with temperature-variable NMR. The results showed the introduction of Aphe with both steric hindrance and carboxyl groups greatly slowed down the shrinkage of PNTA-BISS nanogels. Therefore, PNTA-BISS nanogels can form sol–gel transition and further structural color of hydrogel photonic crystals due to carboxyl groups above the T p. Furthermore, the properties of biodegradable hydrogel photonic crystals above the T p were investigated for the first time, attributed to the presence of the strong reducing agent 1,4-dithiothreitol (DTT). When loaded with doxorubicin (DOX), PNTA-BISS exhibited favorable degradation properties under the influence of DTT. In summary, the PNTA-BISS nanogel, in addition to its in-situ gelation capabilities, demonstrated degradability, potentially providing a novel nanoplatform for applications in drug delivery, biotechnology, and related fields. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis, in short called as RA, is a severe auto-immune condition characterized by thickening of the synovium joints, inflammation and soreness of joints, which subsequently destroys the articular structures. The drug used to treat RA requires the delivery of a formulation in intact form to synovial joints and release of a whole amount of medicine into synovial fluids. Apremilast is an anti-inflammatory drug used to treat arthritis, but its oral drug delivery is limited because of its low bioavailability and side effects. The nanoparticle-based in situ gel helps in prolonged formulation retention, which enables drug release within specific tissues such as cartilage and synovium. The purpose of this research is to formulate and assess the efficacy of a thermosensitive in situ gel of nanosized apremilast for managing RA. A total of nine apremilast- loaded nanoparticles in situ gels designated as F1–F9 were prepared with different ratios of Eudragit RSPO and polyvinyl alcohol using 25% w/v poloxamer 407 and poloxamer 188 as gelling agents. Among the various formulations, F5 showed a particle size of 119 nm, 80.8% EE, 27.54% DL, 37.5 ± 1.7∘C gelation temperature, 55 ± 1.0 second gelation time and 866 ± 13 cps viscosity, with a better in vitro drug release profile of 75.54% for 24 h by non-Fickian diffusion mechanism; thus, it was chosen as the most productive formulation. In an in vivo study in rats, the optimized formulation reduced inflammation at the test site. The developed nanoparticles in situ gel will be a novel carrier system for drugs used to treat RA. [ABSTRACT FROM AUTHOR]

Hydrogels have found wide applications in various fields, but further advances in hydrogel-based applications hinge upon overcoming the challenge of generating complex structures. Although three-dimensional (3D) printing enables customized designs, it remains challenging to print hydrogel structures directly without using supporting materials or incorporating polymeric or solid thickeners due to the low printability of hydrogel precursor solutions. Here, we demonstrate that direct 3D printing of sodium alginate (SA) hydrogel structures can be achieved by introducing ethanol into the SA solution. On the one hand, ethanol enables a sol-to-gel transition to occur by lowering the temperature. Our molecular dynamics (MD) simulations reveal that the gelation occurs due to disrupted hydrogen bonding interaction among SA chains and water. On the other hand, the presence of ethanol notably increases the viscosity, yield stress, and shear-thinning feature of SA solution, making it an ideal 3D printing ink. An isotropic shrinkage of the printed structures is observed after further gelation with Ca2+ ions and the removal of ethanol. Our study provides an effective approach for direct printing of SA hydrogels with enhanced printing resolution (>10 %), paving the way for more advanced hydrogel-based applications in various fields.

The gelation of PEGylated gold nanoparticles dispersed in a glycerol–water mixture is probed in situ by x-ray photon correlation spectroscopy. Following the evolution of structure and dynamics over 104 s, a three-step gelation process is found. First, a simultaneous increase of the Ornstein–Zernike length ξ and slowdown of dynamics is characterized by an anomalous q-dependence of the relaxation times of τ ∝ q−6 and strongly stretched intermediate scattering functions. After the structure of the gel network has been established, evidenced by a constant ξ, the dynamics show aging during the second gelation step accompanied by a change toward ballistic dynamics with τ ∝ q−1 and compressed correlation functions. In the third step, aging continues after the arrest of particle motion. Our observations further suggest that gelation is characterized by stress release as evidenced by anisotropic dynamics once gelation sets in. [ABSTRACT FROM AUTHOR]

We investigate the rheo-mechanical properties of Mebiol Gel®, a thermosensitive gel-forming polymer extensively used as a medium for cellular culture, using passive microrheology made either by standard dynamic light scattering or by photon correlation imaging. In the dilute limit, Mebiol displays a Newtonian behavior with an effective viscosity that decreases with temperature, consistent with a peculiar aggregation mechanism characterized by an increase of the molecular weight with a simultaneous reduction of the aggregate size. By increasing concentration and approaching gelation, both the storage and loss moduli show a nonmonotonic dependence with temperature, with a pronounced maximum around Tm ≃ 28–30 °C, the value above which, in the dilute limit, the individual Mebiol chains are fully compacted. Such a distinctive trend of the elastic and viscous properties persists within the gel, which, therefore, becomes "softer" above Tm. Although when temperature changes are performed adiabatically, the transition from the fluid to the gel phase takes place without any apparent discontinuity, a rapid T-jump leads to the formation of a hard gel at a concentration where a low heating rate conversely yields a fluid phase. This is a visible manifestation of the nonequilibrium nature of these physical gels. [ABSTRACT FROM AUTHOR]