Owing to their high-water contents, low calorie density, easy-to-swallowing properties, polysaccharide gels have attracted increasing attention in the food industry and almost exist in our every day’s life. Gelation is one of the most important properties for polysaccharides, which describes a process of chain-chain aggregation and the formation of a three-dimensional network structure that finally leads to a drastic change in the macroscopic mechanical properties, i.e., from a solution with good fluidity to a gel with self-supporting property. Moreover, the gelation process is also considered to cause remarkable changes in the microenvironments in the interspatial network and in the polymer chain’s mobility as well as the polymer-water interactions. Therefore, it is important to have a fundamental understanding of how polysaccharides form gels from macroscopic, microscopic to molecular levels. In this review article, we have summarized the application of bulk rheology, particle tracking, light scattering, nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) and some other tools in elucidating the network structures and gelation mechanism of typical gelling polysaccharides gellan and carrageenans. It has been demonstrated that these techniques are powerful to provide important information on the gelation mechanism and network structure at different length scales.

In this study, a positively charged emulsifier was developed by hydrophobic modification of chitosan with linoleic acid (LA), and a 5 % LA grafting degree was subsequently confirmed by TLC, 1H NMR, and DOSY measurements. The emulsifying ability of chitosan was markedly improved by LA modification, which allowed the preparation of a stable nanoemulsion at more than 0.5 % (w/w) emulsifier concentration after 5-10 microfluidizati on passes. Under these conditions, the LA-chitosan stabilized emulsion exhibited a unimodal nanoscale droplet size distribution and remained creaming-free during 29 days of storage. Compared with SDS-stabilized nanoemulsions, which exhibited significant destabilization in the presence of positively charged proteins, the LA-chitosan-stabilized nanoemulsions maintained high stability. The results suggest that LA-chitosan has potential for use as a food-grade emulsifier for the formulation of stable nanoemulsions.

Chitosan-based films are promising alternatives to petroleum-based food packaging materials but suffer from insufficient mechanical strength, poor water resistance, and limited antioxidant capacity. To address these issues, we synthesized chitosan-based nano-polymers loaded with luteolin (Lut) and superoxide dismutase (SOD) (CLS nano-micelles). We then incorporated these nano-micelles into a chitosan-based film to produce a CLS film. The results showed that, compared with the pure chitosan film, the mechanical properties of CLS film significantly improved, with tensile strength increasing from 6.14 MPa to 37.50 MPa and elongation at break increasing from 17.4% to 34.6%. The barrier properties of the CLS film were also enhanced, as both water vapor permeability and solubility decreased. Notably, the CLS film also exhibited excellent antioxidant properties (with DPPH inhibition rates increasing from 4.4% to 48.3% and ABTS inhibition rates rising from 7.2% to 74.6%) and demonstrated potent antibacterial activity against E. coli, S. aureus, and B. subtilis. It also exhibited excellent biocompatibility and demonstrated favorable biodegradability in soil. Grape preservation assays further confirmed its efficacy in maintaining fruit freshness. These results demonstrate that integrating CLS nano-micelles into a chitosan matrix significantly improves its mechanical, barrier, antioxidant, and antibacterial properties. This makes the CLS film a promising eco-friendly alternative for sustainable food packaging applications, offering an efficient and environmentally friendly solution.

The gelation process of two deacetylated gellan (DG) fractions with different molecular weights (DG-1: Mw approximate to 671 kDa, DG-2: Mw approximate to 504 kDa) was studied at a fixed DG concentration (1.0 %, w/w) and varying sucrose concentrations (0-60 %, w/w). Rheological measurement suggested that sucrose addition promoted the gelation temperature (Tgel) of DG-1 in a concentration-dependent manner, with the Tgel shifting from 28, 31, 40-44 degrees C in 0, 20, 40 and 60 % sucrose solutions, respectively. This result is well consistent with the data of particle tracking experiment, where the ensemble mean square displacements (MSD) of the probe particles (1.0 mu m) steeply decreased around the Tgel for each sucrose DG-1 solution, reflecting a diffusional confinement by forming gel network. Micro-DSC data suggested that the ordered structure formation temperature (Torder) of DG-1 was also enhanced by sucrose addition, with Torder approximate to 28, 31, 37 degrees C for 0, 20, 40 % sucrose addition, respectively. However, at 60 % sucrose concentration, no exothermic peak was observed, possibly indicating that high concentration sucrose induced a DG network structure crosslinked by intermolecular point-to-point hydrogen bonding. Moreover, 1H NMR measurement suggested the molecular mobility of DG chains significantly decreased around the Tgel for each sucrose DG-1 solution. However, at 60 % sucrose concentration, the NMR spectrum of DG-1 became much less detectable, possibly due to a high solution viscosity that significantly decreased DG chain mobility. Compared with DG-1, DG-2 displayed a gelation behavior similar to that of DG-1, but with a slightly weaker gelling ability due to smaller Mw.

Drilling fluid loss is a major challenge facing oil and gas drilling operations worldwide and often results in significant economic losses. Although traditional liquid-crystal materials (LCMs) offer key advantages such as self-adaptive crack plugging capabilities and adjustable gelation times. However, due to its limited pressure resistance, its range of applications remains limited. In this study, a simple freeze-thaw strategy was employed to innovatively develop a PVA-based plugging hydrogel. This method leverages physical cross-linking properties to reduce the need for chemical cross-linking agents and improve the material's rheological properties. The 15% PVA hydrogel achieved a tensile strength of 6.99 MPa. Its compressive strength was 4 MPa at 80% strain. Furthermore, it exhibited excellent fatigue resistance, with compressive strength decreasing by only 21% after 50 cycles. Simulated plugging tests demonstrated that the prepared hydrogel exhibits excellent sealing performance under a water pressure of 5 MPa. This study provides an economically viable and environmentally friendly solution for preventing drilling fluid loss, making it a highly promising candidate material for deep-sea drilling applications.

Due to limitations in stability, solubility, and functional properties, natural proteins often fail to meet the demands of industrial production. Traditional chemical or enzymatic methods for protein modification suffer from high costs and the generation of numerous byproducts. In contrast, physical techniques offer a new approach to the green modification of macromolecules by inducing structural changes in proteins. Based on these techniques, the construction of protein-polyphenol composite systems is considered an effective strategy for enhancing food quality. This article systematically reviews the molecular mechanisms by which physical fields regulate protein-polyphenol interactions, summarizes how physical techniques improve the functional properties of composite systems and their applications in food, and aims to provide theoretical support for the development of novel functional food ingredients and their industrial applications.

In this study, Cyperus esculentus starch (CES) and proteins (CEP) were combined with casein to prepare composite gels, and their gelling behaviors were characterized in a simulated casein-rich food gel system (e.g., yogurt). It was found that hydrophobic interactions were the primary driving force stabilizing both casein-CEP and casein-CES gels, but CES and CEP interacted with casein via different mechanisms. Specifically, CES could effectively occupy the pores of casein gels and interact with casein proteins owing to its branched structure and high viscosity. As CES increased, the interaction increased the surface hydrophobicity, crystallinity, and beta-sheet content of the casein-CES gels, thereby enhancing the gel structure, water-holding capacity, binding capacity, and textural properties. A gradual increase in CES improved the textural properties of casein-CES gels, with the effect becoming pronounced when the casein: CES ratio exceeded 1: 0.8. Alternatively, the effect of CEP incorporation on casein gels was highly dependent on its concentration, with low concentrations filling the gel pores to improve gel texture and high concentrations inducing significant phase separation. When the mass ratio of casein to CEP was below 1: 0.025, an increase in the amount of CEP enhanced the stability of the gel structure. When the mass ratio of casein to CEP exceeded 1: 0.025, increasing CEP led to gradual phase separation, which was detrimental to improving gel characteristics. Overall, CES and CEP could serve as natural ingredients to improve casein-rich gel products; however, their inclusion levels should be optimized to achieve desirable gel properties.

Peach fruits stored at 5 °C are prone to woolliness, mainly due to pectin gel. The gel capacity of different pectin fractions in vitro and the contribution of internal conditions were analyzed. Results indicated that compared with fruits stored at 10 °C, those at 5 °C had lower sucrose and higher glucose and fructose. Metal ion content, especially Ca2+, initially increased then decreased. Decline in pectin methylesterase activity was less than that in polygalacturonase activity. Water-soluble and chelator-soluble pectin (WSP and CSP) stored at 3 and 4 weeks formed gel with tissue fluid, whereas alkali-soluble pectin remained fluid. Low-field NMR and rheology confirmed these findings, which resulted from the relatively high molecular weight, low degree of esterification, and elevated homogalacturonan ratio. Sucrose and acidic conditions provided an environment conducive to gel and the elevated Ca2+ benefited for gel formation, providing direction for elucidating gel mechanism in peach fruit.

In this study, an apple polysaccharide (AP) that exhibited a gelatin-like gelation behavior has been reported, with the gelation mechanism being further revealed. It was found that a suitable amount of Ca2+ addition (4.5 mmol·L-1) induced the formation of AP gels at 0.5% (w/v) polymer concentration in a wide pH range (3.0-8.0) by holding the polysaccharide solution at 4 °C. However, no gel was formed in the absence of Ca2+. Meanwhile, all gels melted around 33 °C upon reheating, and the change in pH did not significantly affect the formation and melting processes of the AP gels. Furthermore, ITC and EPR measurements indicated no detectable binding of Ca2+ to AP chains. Thus, the gelation mechanism was explained as Ca2+-mediated electrostatic screening, whose presence facilitated AP chain-chain association and ultimately triggered network formation. Our results suggested that AP may exhibit high potential as a possible gelatin substitute in food production.

This study explored the role of the galloyl moiety (GM) in protein-polyphenol interactions by examining the binding between Cyperus esculentus protein (CEP) and six tea polyphenols (TPs). Fluorescence quenching results indicated that TPs statically bound to CEP, and the quenching constants of galloylated catechins (CGMs) were significantly higher than non-galloylated counterparts (Cs), suggesting that GM groups enhance the binding affinity. Spectral analyses revealed that CGMs induced the protein α-helix content decreased and β-sheet and random coil structures increased. Surface plasmon resonance and thermodynamic analyses confirmed that the GM groups promote specific binding through hydrogen bonding and hydrophobic interactions. Furthermore, galloylation facilitated larger complexes formation with higher surface charge density, significantly affecting the system turbidity, solubility, and emulsifying properties. This study clarified the differential regulatory effects of CGMs and Cs on the structure, binding affinity, and thermodynamic behavior of CEP, providing theoretical guidance for the precise design of protein-polyphenol composite systems.

Current clinical therapeutic protocols for diabetic foot ulcers (DFUs) remain inadequate due to their low response to therapeutic drugs and high recurrence rates. The normal healing process of diabetic wounds is frequently disrupted by factors such as microbial infections and elevated reactive oxygen species (ROS) levels. In this study, we developed a gel patch that can accelerate wound re epithelialization and scavenge ROS and antibacterial. To provide a dependable biological framework for wound tissue regeneration, this patch incorporates two components analogous to the extracellular matrix: snail glycosaminoglycan and gelatin. The multifunctional patch exhibited potent antibacterial activity, eliminating over 99.9 % of Staphylococcus aureus and Escherichia coli, and reduced reactive oxygen species (ROS) levels in oxidative stress-induced cells by 80 %. In a diabetic wound infection model, the patch inhibited bacterial colonization, accelerated re-epithelialization by two-fold, and lowered inflammatory markers, highlighting its dual antimicrobial and pro-healing effects. The patch demonstrated a precisely synchronized gradual degradation and controlled drug release profile, which aligned with the spatiotemporal dynamics of wound healing progression. In summary, this innovative approach presented a facile, safe, and highly efficient therapeutic strategy for the management of DFUs.

Gelation of deacylated gellan (DG) is influenced by cations, with monovalent ions shielding electrostatic repulsions and divalent ions directly binding DG chains. The role of trivalent ions, however, remains unclear. This study aims to explore the gelation process of DG in the presence of Fe3+ and K+ ions from microscopic and molecular levels. Nuclear magnetic resonance (NMR) techniques, including water 1H T2 and diffusion measurement, were employed to investigate the dynamic information of molecular chains. Multiple particle tracking was used to analyze the gelling evolution at a microscopic perspective. Fe3+ shifted the temperature of ordered structure formation (Tord) lower, attributed to repulsion among -COO Fe+ COO- complexes formed at the gelation. K+ accelerated aggregation via electrostatic shielding. The diffusion coefficient of DG (DDG) gave information about molecular mobility of DG chains. Besides, particle tracking revealed network pore sizes narrowed from 270 to 1100 nm to below 270 nm as the gelation progressed. These findings clarify the role of Fe3+ in DG gelation from molecular and microscopic perspectives, offering insights into the gelation mechanism of DG induced by trivalent cations.

Tea polyphenol epigallocatechin-3-gallate (EGCG) has been previously explored as an effective inhibitor of carbohydrate hydrolyzing alpha-glucosidase for regulating postprandial blood glucose level. Proteins act as one common dietary component, the influence of which on alpha-glucosidase inhibition of EGCG remains unknown. In this study, bovine serum albumin (BSA) and isolated whey protein (IWP) were found to significantly weaken the competitive inhibitory activity of EGCG against alpha-glucosidase by the effect order of BSA > IWP, while egg albumin (EA) hardly influenced the enzyme inhibition. Through the analyses of kinetics, spectroscopy, thermodynamics and simulated docking, a protein-EGCG-enzyme ternary complex was suggested to generate in the interaction system, in which there existed competition between proteins (BSA and IWP) and alpha-glucosidase regarding formation of hydrogen bondings with polyphenolic groups (especially galloyl moiety). This weakened the EGCG-enzyme binding interactions at alpha-glucosidase active site, and thus reduced the enzyme inhibition in vitro and in vivo. However, there existed a co-existing relationship between proteins and alpha-glucosidase regarding pi-stackings of EGCG benzene ring with aromatic residues of both macromolecules, which remained the fluorescence quenching ability of EGCG against the enzyme. Conclusively, dietary proteins should be considered as a potential influence factor when developing natural products as inhibitors of carbohydrate hydrolyzing enzymes.

In this study, a newly reported apple polysaccharide (AP) capable of forming gels at ambient temperature or even lower with 0.5 % concentration (w/v) was incorporated in 8.0 % goat milk casein (GMC) dispersion for exploring the potential of AP to stabilize the GMC dispersion at a wide pH range (3.0-7.0). Rheological analysis revealed that the GMC-AP mixture (8.0 % GMC + 0.5 % AP) exhibited remarkable shear-thinning behavior with viscosity exceeding 1000 Pa·s at low shear rate (0.1 s-1) in pH 3.0-5.0 range. This superior stability stemmed from electrostatic interactions that peaked at pH 3.0 (inducing associative phase separation) and moderately weakened at pH 4.0-5.0 while maintaining system integrity. Multimodal characterization through Zeta-potential, UV-vis/fluorescence spectroscopy, FTIR, and ITC confirmed the pH-responsive binding patterns. SAXS and atomic force microscopy further revealed the formation of intermolecular complexes at pH 3.0-5.0. At higher pH range (6.0-7.0), the viscosity of the system greatly decreased, where the aggregation between AP and GMC as induced by electrostatic interaction still existed but became extremely weaker. Considering AP can stabilize GMC dispersion especially at pH 4.0-5.0, our results may highlight the potential application of AP in GMC-based acidic dairy products.

Biological nanotechnologies based on functional nanoplatforms have synergistically catalyzed the emergence of cancer therapies. As a subtype of metal-organic frameworks (MOFs), zeolitic imidazolate frameworks (ZIFs) have exploded in popularity in the field of biomaterials as excellent protective materials with the advantages of conformational flexibility, thermal and chemical stability, and functional controllability. With these superior properties, the applications of ZIF-based materials in combination with various therapies for cancer treatment have grown rapidly in recent years, showing remarkable achievements and great potential. This review elucidates the recent advancements in the use of ZIFs as drug delivery agents for cancer therapy. The structures, synthesis methods, properties, and various modifiers of ZIFs used in oncotherapy are presented. Recent advances in the application of ZIF-based nanoparticles as single or combination tumor treatments are reviewed. Furthermore, the future prospects, potential limitations, and challenges of the application of ZIF-based nanomaterials in cancer treatment are discussed. We except to fully explore the potential of ZIF-based materials to present a clear outline for their application as an effective cancer treatment to help them achieve early clinical application.

It was found that the serine protease inhibitors BmSPI38 and BmSPI39 in silkworm can strongly inhibit the activity of porcine pancreatic elastase, which has potential applicational value in the drug research and development of lung diseases, inflammatory diseases, and skin aging caused by the excessive release of elastase. Previous studies have shown that homotypic multimers obtained by tandem expression can significantly enhance the antifungal activity and structural homogeneity of BmSPI38 and BmSPI39, while the effect of the tandem expression of these two inhibitors, with different combinations, on the total activity and expression levels of multimers remains unclear. The aim of this study is to explore whether it is possible to obtain the combination of BmSPI38 and BmSPI39 with strong total expression activity by protein engineering. In this study, 40 tandem multimer expression vectors with different combinatorial forms of BmSPI38 and BmSPI39 were constructed by the isocaudomer method, and recombinant proteins were obtained by the prokaryotic expression system. The target proteins were separated by SDS-PAGE to analyze the expression levels of multimer proteins with different combinatorial forms. The total activity of the recombinant expression products with different tandem forms was investigated using the in-gel activity staining technique of protease inhibitors. The SDS-PAGE results show that the expression levels of tandem multimers containing the BmSPI39 module at the carboxyl terminus were generally higher in the Escherichia coli supernatant than that of the tandem multimers containing the BmSPI38 module at the carboxyl terminus. The activity staining results indicate that compared with BmSPI38 and BmSPI39 homotypic multimers, the total activity of some recombinant expression products with different tandem forms was stronger. Furthermore, the total activity level was relatively higher when the carboxyl terminus of the multimer was a BmSPI39 module, such as the tandem dimers SPIAB and SPIaB and the tandem trimers SPIabB, SPIaaB, and SPIbaB. In this study, the expression of tandem fusion proteins with different combinations of the silkworm protease inhibitors BmSPI38 and BmSPI39 in E. coli was successfully achieved. It was confirmed that the tandem of different combinatorial forms, based on protein engineering, was an effective way to enhance the total activity of the fusion proteins of BmSPI38 and BmSPI39 and to improve their expression levels. Additionally, a number of multimer proteins with strong total activity and high exogenous expression levels were also screened, for example, SPIbaA, SPIbbA, SPIbbB, SPIabB, SPIaaB, and SPIbaB. This study not only lays the foundation for the exogenous production and development of BmSPI38 and BmSPI39 but also provides a reference for the construction of tandem and multimerization exploration of other protease inhibitors.

Inhibiting the activity of essential carbohydrate-hydrolyzing α-amylase is considered as a promising approach in regulating postprandial blood-glucose level. The enzyme inhibition effect is usually determined through substrate hydrolysis, which brings a challenge regarding inhibitory activity fluctuation as substrate enzymolysis modes cause difference in α-amylase inhibition. Herein, we innovatively established a thermodynamics-inhibition model for evaluating α-amylase inhibitors that was afterwards independent of substrate digestion. During model establishment, the direct inhibitor-enzyme binding affinity (1/Kd) was determined by microscale thermophoresis (MST) using a specific histidine-labelling tag based on ligand-receptor binding behaviors, along with critical inhibiting parameters through inhibition analysis including inhibitory activity (IC50) and competitive inhibition coefficient (1/Kic). Then, the regularly positive correlation between thermodynamic binding affinity and enzyme inhibition was specifically found across a weak-to-strong inhibiting range. This confidently provided the model with an ability in evaluating α-amylase inhibition of a potential inhibitor, based on which the landmark 1/Kd threshold for gradient inhibitory activity compared to positive control was obtained. Through this model, galloyl moiety, especially with configurational freedom, was indicated as a promising active moiety in natural product discovering and pharmaceutical synthesis for α-amylase inhibitors. Conclusively, the thermodynamics-inhibition model provided an efficient approach in assessing α-amylase inhibitors in a substrate-free mode.

Woolliness in peach fruit during low-temperature storage considerably reduces quality, primarily owing to the formation of pectin gel. This study systematically analysed texture, water distribution, cell wall microstructure, and pectin gel formation during peach storage. Peaches stored at 5 °C exhibited increased firmness, membrane permeability, and water binding capacity than those at 10 °C. These changes resulted in cell wall thickening and reduced extractable juice. Low-field nuclear magnetic resonance (LF-NMR) revealed an enhanced interaction between water and pectin. Rheological analysis indicated a transition from viscoelastic fluid to a solid/gel state after one week of storage, with a distinct gel structure forming after three weeks. Additionally, increased arabinose (Ara) and galacturonic acid (GalA) contents, including the retention of high molecular weight pectin and a low degree of esterification at 5 °C, were observed, which may have promoted gel formation. These findings provide new strategies for managing fruit woolliness under low-temperature conditions.

With the development of modern industry, the water pollution is getting severer which causes the huge environmental problems. In this work, the novel photocatalytic polyelectrolyte composite hydrogels based on crosslinked poly(2-acrylamido-2-methylpropane sulfonic acid) equipped with graphite carbon nitride (g-C 3 N 4 ) were exploited via a facile preparation route, which exhibited extremely high removal ratio of 95 % and 94.5 % to Rhodamine B and tetracycline, respectively, through the synergistic effect of adsorption and photodegradation. Remarkably, the recyclability was also observed on the as-prepared hydrogels, which enabled to reuse for 15 times with the few attenuations of removal efficiency to contaminants. This study provides the new insights into the photocatalyst composite hydrogel and possesses the profound significance of the treatment of organic pollutants.

The effect of trivalent cation Fe3+ on the gelation process of a sodium salt form of gellan (DG, deacylated gellan gum) was investigated by rheology and DSC studies. On addition of a fairly low concentration of Fe3+ (1 mM), both the complex modulus (G*) of a 1.0 % DG solution in gel state and the sol-gel transition temperature (Tgel) slightly decreased. At higher Fe3+ concentrations (2 and 3 mM), however, a slight increase in the G* and Tgel was observed. In the coexisting monovalent cation (K+) solutions, addition of Fe3+ always improved the G* in gel state and the Tgel in a concentration-dependent manner. Moreover, for all Fe3+ DG solutions, the ordered structure formation temperature (Torder) was always lower than Tgel and increased with increasing Fe3+ concentration. This finding indicates that the network formation in the DG solutions should occur in advance of the ordered structure formation of the DG chains and that the presence of Fe3+ unfavorably affected the conformational transition of DG. In coexisting cation solution, the presence of K+ ion made a favorable contribution to the binding of Fe3+ to the disordered DG chains and to the subsequent ordered structure formation of the DG chains.