Structural Characterization of Sodium Alginate and Calcium Alginate

Characterizations of two physically modified sodium alginate composite films doped with gallic acid and their preservation of refrigerated sea bass (Lateolabrax maculatus)

In order to reduce the environmental pressure caused by polyethylene packaging, the study developed gallic acid (GA) containing active films by blending and cross-linking, characterized the effect of different GA contents on the two films, and explored the preservation effect of sea bass wrapped in films containing 2 mg/mL GA and refrigerated at 4 °C for 15 days. The characterization results showed that CF (cross-linked film) had better mechanical and barrier properties than BF (blended film). The microstructure showed that CF had a denser structure than BF. The GA-containing membrane showed complete shielding against UV of about 300 nm. Both membranes showed free radical scavenging of up to 80 % DPPH. The shelf-life of fish wrapped with BF and CF was extended by 6 days compared to the control. Thus, gallium-containing BF and CF are used as renewable films for active packaging to protect products from UV, oxygen and microorganism.

Mixed-Solvent-Induced Phase Separation Enables Anisotropy and Strengthening of Hydrogels Composed of Flexible Network Chains

Achieving anisotropy in hydrogels is key to replicating the structural and mechanical properties of biological tissues. However, inducing anisotropy in hydrogel systems composed solely of flexible amorphous polymers is challenging, as these polymers typically exhibit thermally unstable anisotropic states, i.e., they are easy to disorient. In this study, a mixed-solvent-induced phase-separation approach to stabilize the orientation of such hydrogel networks after pre-stretching is introduced. Using polyacrylamide, a flexible polymer with a persistence length on the order of 10-1 nm, as a model system, it is demonstrated that phase separation in a mixed solvent leads to the formation of dense and dilute polymer phases, with the dense phase effectively locking the anisotropy through robust inter- and intra-polymer interactions. A series of characterizations confirm that partial orientation can be preserved in the prestretched, phase-separated gel upon relaxation, resulting in significant mechanical enhancement along the orientation direction, including improvements in fracture stress, Young's modulus, and fracture toughness. The generality of this method, showing its effectiveness in other hydrogel systems and its adaptability to different solvent combinations is also validated. This work presents an unconventional strategy for preparing anisotropic hydrogels that typically struggle to maintain structural integrity.

Enhanced bone regeneration using mesenchymal stem cell-loaded 3D-printed alginate-calcium Titanate scaffolds: A Calvarial defect model study

This study investigates the efficacy of a 3D-printed alginate composite scaffold enriched with calcium titanate nano powders and loaded with mesenchymal stem cells (MSCs) for bone regeneration in a calvarial defect model. Scaffolds (20 mm × 20 mm × 4.48 mm) with a slightly rough surface texture were fabricated using a bioprinter. A calvarial defect was created in the skulls of forty male Wistar rats, then divided into four treatment groups: empty defect, scaffold only, MSCs only, and MSC-seeded scaffold. After eight weeks, new bone formation was evaluated. The MSC-seeded scaffold group showed superior outcomes, including significantly higher bone mineral density (BMD), nearly complete defect closure in CT imaging, and enhanced histological results with newly formed bone and marrow cavities. Osteogenic gene markers (RunX2, OSX, COL1, BMP2, and OCN) and the angiogenic marker VEGF were notably upregulated, while the osteoclast-related gene RANKL was downregulated. These findings highlight the synergistic effect of the scaffold's osteoconductive properties and MSCs' regenerative potential. MSC-seeded alginate‑calcium titanate scaffold demonstrates promising results for critical-sized defect repair and may serve as a viable strategy for clinical bone tissue engineering applications.

pH-sensitive chitosan/sodium alginate/calcium chloride hydrogel beads for potential oral delivery of rice bran bioactive peptides

Although rice bran active peptide (RBAP) has potent antioxidant properties, its practical applications have been limited by its low bioavailability. In this study, we hypothesized that pH-responsive hydrogels prepared from the ionic gelation between chitosan and alginate could be a promising delivery system of short-chain peptides, like RBAP, for protecting them from chemical degradation during digestion and improving their functionality. The hydrogel beads retained RBAP in the gastric environment due to strong interactions between two biopolymers and RBAP, followed by a sustained release of more than 70 % peptide in the intestinal condition, thus improving its gastrointestinal stability. The RBAP-loaded hydrogel beads not only significantly enhanced free radical scavenging ability by 3-7 times during digestion but also protected human umbilical vein endothelial cells from H2O2-induced oxidative stress after digestion. This study presents a novel hydrogel platform for enhancing the gastrointestinal stability and functional efficacy of RBAP and other water-soluble peptides.

Intra- and Interbead Communications by an Anchored DNA Structure and Cascaded DNA Reactions

In nature, communication between compartments, such as cells and organelles, gives rise to biological complexity. Two types of chemical communication play important roles in achieving this complexity: intra- and intercompartment communication. Building a bioinspired synthetic system that can exhibit such communication is of interest for realizing microscale artificial robots with the complexity of actual cells. In this study, we aimed to demonstrate intra- and interbead communication using microbeads made of hydrogels as compartments. We employed the diffusion and reaction of programmed DNA molecules as a medium for chemical communication. As a result of the reaction-diffusion dynamics of DNA, the spatiotemporal development of fluorophore-labeled DNAs was observed under fluorescence microscopy, showing both intra- and interbead communication. Our simple, robust, and scalable methodology will accelerate the fabrication of synthetic microsystems that may have complex functionalities from various local interactions.

Indenting at the Microscale: Guidelines for Robust Mechanical Characterization of Alginate Microgels

Microgels offer broad applications in bioengineering due to their customizable properties, supporting innovations in mechanobiology, tissue engineering, drug delivery, and cell therapy. This study focuses on characterizing ionically cross-linked alginate microgels using a nanoindentation technique, enabling precise assessment of their mechanical properties at the microscale. We report on the microfluidic fabrication of alginate microgels with varying sizes at different cross-linker concentrations and on the mechanical characterization of the resulting microgels in terms of Young's moduli as well as viscoelastic behavior. Measurements conducted using dynamic nanoindentation reveal that microgel elasticity is strongly influenced by the ionic composition of the surrounding media, in particular, the concentration of calcium and sodium. We demonstrate that the highest Young's modulus observed for ionically cross-linked alginate microgels is in deionized water (7.2 ± 0.9 kPa). A drastic softening effect is observed when the calcium cross-linked microgels are placed into a storage buffer containing divalent ions (0.7 ± 0.1 kPa) and cell culture media consisting of Dulbecco's Modified Eagle Medium (0.2 ± 0.1 kPa) with fetal bovine serum (0.4 ± 0.1 kPa). High concentrations of sodium were found to disrupt ionic cross-links, decreasing stiffness and increasing viscosity, with reversible effects observed upon switching back to deionized water. These findings highlight the importance of media selection for applications requiring mechanical stability, and we provide guidelines for measuring the mechanical properties of microgels in a robust manner that is applicable to a wide range of different conditions.

Alginate-polyacrylamide double-network hydrogel sensors: Biomass-based piezoresistive platform with liquid metal and convex array for enhanced sensitivity

The hydrogel sensors with outstanding tensile strength, high sensitivity, broad sensing range and excellent stability are highly desired for flexible electronics. Here, a double network piezoresistive flexible hydrogel sensor equipped with a convex structure was fabricated using the template method, which consists of CMCNTs-PAM/SA-Ca2+ convex array and ultra-high-conductivity liquid metal droplets (LMs). Such a novel hybrid architecture enables the prepared piezoresistive sensor to have high sensitivity (GF up to 32.42), fast response time (209 ms), good cyclic stability (ultra 2000 cyclic tensile), and excellent strength. Due to its good comprehensive monitoring performance, the double network hydrogel sensor can be used for human activity monitoring, providing a tremendous potential in electronic wearable devices.

Poly(Acrylic Acid)-Sodium Alginate Superabsorbent Hydrogels Synthesized Using Electron-Beam Irradiation-Part III: An Evaluation of Their Degradation in Soil

Global challenges in agriculture, in terms of water and nutrient loss control, require new approaches to maintaining or even increasing crop production. Promising materials, such as superabsorbent hydrogels of hybrid types obtained from natural polymers grafted with synthetic polymers, represent a viable solution to solve these problems and maintain a clean environment. In view of this, two types of hydrogels based on sodium alginate, acrylic acid and polyethylene oxide obtained using 5.5 MeV electron-beam irradiation were subjected to degradation through burial in the soil. Swollen hydrogels in two types of water (distilled and tap) and two types of nutrient solutions (synthetic nutrient solution and 100% natural organic nutrient solution), with different pHs of 5.40, 6.05, 7.45 and 7.66, were buried in soil for 30 and 60 days and then extracted and analyzed in terms of their mass loss, swelling behavior and cross-linking structure. The highest mass losses after both 30 and 60 days were recorded for the hydrogels buried in soils whose humidity was maintained by watering them with the basic solutions (tap water and the organic nutrient solution). Structural modifications associated with the degradation process were highlighted by decreases in the cross-link densities and increases in the mesh sizes and swelling. These results were confirmed using FTIR and SEM techniques.

Assembling Carbon Nanotube and Graphene in Chitosan/Sodium Alginate Hydrogels for Ion Removal Applications

Hydrogels have emerged as a promising material for the removal of heavy metal ions from contaminated water owing to their high water absorption capacity and biocompatibility. Despite notable advancements in improving the adsorptive capacity of hydrogels, the demand for a more efficient structure persists. Here, we explore the ion adsorption performance of crosslinked hydrogels based on chitosan and sodium alginate with various ratios of carbon nanotubes (CNT) and graphene platelets (GNP). This study highlights the adsorption of chromium ions and the thermal stability of hydrogels for pure, single-particle, and hybrid nanocomposites. The results depict a uniform microstructure attained when CNT, GNP, or both are implemented into the hydrogel due to the strong interaction of functional moieties. The incorporation of CNT and GNP manipulates the crystalline structure of the hydrogels, lowering their crystallinity by around 28% and 13%, respectively. The synergistic effect of CNT and GNP in hybrid hydrogels raises the decomposition temperature by 16%, indicating a favorable interplay interaction between nanoparticles and polymers. Calculations of the adsorption capacity accentuate such a mutual effect between CNT and GNP in various loads of ion capture from aqueous solutions. Kinetic models fitted to the hydrogel nanocomposites reveal that the pseudo-second-order model aligns better with the experimental data in comparison to the pseudo-first-order and intraparticle diffusion models, addressing the adsorption mechanisms while capturing chromium ions.

Molecular Dynamics Study of Polyacrylamide and Polysaccharide-Derived Flocculants Adsorption on Mg(OH)2 Surfaces at pH 11

Brucite (Mg(OH)2) is a typical precipitate in the mining industry that adversely affects processes such as flotation and thickening. Gaining insights into the physicochemical properties of this mineral is critical for developing strategies to mitigate these challenges and improve operational efficiency. Additionally, incorporating natural-origin polymers aligns with the shift toward more sustainable mining practices. In this study, molecular dynamics simulations were employed to investigate the interaction of brucite with polysaccharides such as cellulose, guar gum, and alginate and to compare these with conventional polymers, including polyacrylamide, hydrolyzed polyacrylamide, and polyacrylic acid, under conditions of pH 11 in low-salinity water. The methodology enhanced adsorption sampling by incorporating additional temporary interactions between the polymer and the brucite surface. The results reveal that neutral polymers exhibit stronger and more stable interactions with brucite compared to charged polymers, which is consistent with the neutral nature of brucite under the studied conditions. Van der Waals forces predominantly govern the adsorption of polysaccharides, while Coulombic forces primarily drive interactions involving polyacrylamides. These findings provide valuable insights into the molecular mechanisms of polymer-brucite interactions, facilitating the development of more effective and sustainable mining additives.

Truxillic calcium supramolecular skeleton fortified pH responsive and biodegradable alginate hydrogel films promoting fruit preservation

This work presented a unique alginate hydrogel film fortified by truxillic calcium skeleton with notable physicochemical and mechanical properties, as well as the promising application in fruit preservation. A series of truxillic‑calcium-alginate (CBDA-Ca/SA) films were prepared. It was found that CBDA-10-Ca/SA can block over 50 % of UV-visible light. The maximum breaking strengths of (6 % CBDA-1-Ca)/SA and (2 % CBDA-10-Ca)/SA are 82 MPa and 79 MPa, about twice that of Ca/SA. CBDA-11-Ca/SA showed the highest WVP of 2.18 × 10-10 g ∙ m-1 ∙ s-1 ∙ Pa-1 and CBDA-10-Ca showed the best performance in reducing the OTR of the films by 4.1× 10-5 cm3 ⸱cm ⸱ m-2 ⸱ 24 h-1 ⸱ Pa-1. With water absorption ranging from 3480 % in an acidic environment to 9520 % in an alkaline environment, the CBDA-10-Ca/SA film demonstrated exceptional pH responsiveness. The degradation rate of all films was around 70 % after four weeks of burial under the soil. The above studies indicate that polyphenols can not only act as "hooks" to grasp Ca2+ to form supramolecular skeleton structure improving the mechanical strength of SA-based films, but also act as active components to endure the functional properties of SA-based films with antibacterial and antioxidant properties.

Hydrogel-Assisted Robust Supraparticles Evolved from Droplet Evaporation

Supraparticles, formed through the self-assembly of nanoparticles, are promising contenders in catalysis, sensing, and drug delivery due to their exceptional specific surface area and porosity. However, their mechanical resilience, especially in dimensions spanning micrometers and beyond, is challenged by the inherently weak interactions among their constituent building blocks, significantly constraining their broad applicability. Here, we have exploited a robust supraparticle fabrication strategy by integrating hydrogel components into the assembly system and evaporating on the superamphiphobic surface. The resultant SiO2/SA (sodium alginate) supraparticles, achieved by evaporating a 15% volume fraction dispersion of SiO2 nanoparticles containing 18.46 mg/mL of sodium alginate and subsequently cross-linking with Ca2+, demonstrate mechanical robustness with a fracture force of 6.04 N, representing a mechanical strength enhancement of 60 times higher than that prior to the incorporation of the hydrogel component. The supraparticles maintain their original morphology after 30 min of ultrasonic treatment (200 W), demonstrating mechanical stability. This method exhibits generalizability, enabling the customization of supraparticles with various building blocks and hydrogel backbone materials. Based on such a methodology, we have synthesized enzyme-carrying supraparticles, further expanding the potential applications in intricate cascade reactions. The encapsulated glucose oxidase and horseradish peroxidase maintained their inherent reactivity, and such hydrogel-assisted robust supraparticles exhibited exceptional performance in accurate glucose assays, indicating great practical application in biocatalysis.

Progress in Research on Metal Ion Crosslinking Alginate-Based Gels

Alginate is an important natural biopolymer and metal ion-induced gelation is one of its most significant functional properties. Alginate-based hydrogels crosslinked with metal ions are commonly utilized in the food, biomedical, tissue engineering, and environment fields. The process of metal ion-induced alginate gelation has been the subject of thorough research over the last few decades. This review aims to summarize the mechanisms of alginate hydrogels induced by different cations (primarily including Ca2+, Ba2+, Cu2+, Sr2+, Fe2+/Fe3+, and Al3+). Metal ion-induced alginate gelation shows different preferences for α-L-guluronic acid (G), β-D-mannuronic acid (M), and GM blocks. Some metal ions can also selectively bind to the carboxyl groups of guluronic acid. The properties and applications of these alginate-based hydrogels are also discussed. The primary objective of this review is to provide useful information for exploring the practical applications of alginate.

ISO 10993-4 Compliant Hemocompatibility Evaluation of Gellan Gum Hybrid Hydrogels for Biomedical Applications

This study examines the hemocompatibility of gellan-gum-based hybrid hydrogels, with varying gellan-gum concentrations and constant sodium alginate and silk fibroin concentrations, respectively, in accordance with ISO 10993-4 standards. While previous studies have focused on cytocompatibility, the hemocompatibility of these hydrogels remains underexplored. Hydrogels were formulated with 0.3%, 0.5%, 0.75%, and 1% gellan gum combined with 3% silk fibroin and 4.2% sodium alginate separately, using physical and ionic cross-linking. Swelling behavior was analyzed in phosphate (pH 7.4) and acetic (pH 1.2) buffers and surface morphology was examined by scanning electron microscopy (SEM). Hemocompatibility tests included complete blood count (CBC), coagulation assays, hemolysis index, erythrocyte morphology, and platelet adhesion analysis. Results showed that gellan gum-sodium alginate hydrogels exhibited faster swelling than gellan gum-silk fibroin formulations. SEM indicated smoother surfaces with sodium alginate, while silk fibroin increased roughness, further amplified by higher gellan-gum concentrations. Hemocompatibility assays confirmed normal profiles in formulations with 0.3%, 0.5%, and 0.75% gellan gum, while 1% gellan gum caused significant hemolytic and thrombogenic activity. These findings highlight the excellent hemocompatibility of gellan-gum-based hydrogels, especially the sodium alginate variants, supporting their potential in bioengineering, tissue engineering, and blood-contacting biomedical applications.

High-Resolution Atomic Force Microscopy Investigation of Alginate Hydrogel Materials in Aqueous Media

Alginate hydrogels are frequently used in 3D bioprinting and tissue repair and regeneration. Establishing the structure-property-performance correlation of these materials would benefit significantly from high-resolution structural characterization in aqueous environments from the molecular level to continuum. This study overcomes technical challenges and enables high-resolution atomic force microscopy (AFM) imaging of hydrated alginate hydrogels in aqueous media. By combining a new sample preparation protocol with extremely gentle tapping mode AFM imaging, we characterized the morphology and regional mechanical properties of the hydrated alginate. Upon cross-linking, basic units of these hydrogel materials consist of egg-box dimers, which assemble into long fibrils. These fibrils congregate and pile up, forming a sponge-like structure, whose pore size and distribution depend on the cross-linking conditions. At the exterior, surface tension impacts the piling of fibrils, leading to stripe-like features. These structural features contribute to local, regional, and macroscopic mechanics. The outcome provides new insights into its structural characteristics from nanometers to tens of micrometers, i.e., at the dimensions pertaining to biomaterial and hydrogel-cell interactions. Collectively, the results advance our knowledge of the structure and mechanics from the nanometer to continuum, facilitating advanced applications in hydrogel biomaterials.

Temperature-sensitive injectable chitosan-based hydrogel for endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is an effective treatment for polyps and early gastrointestinal cancers, but requires a high level of operator skill. Injecting submucosal materials (SIM) helps create a fluid cushion between the mucosal and muscular layers, making the procedure easier and reducing associated risks. However, SIMs commonly used in current clinical practice tend to spread quickly and fail to provide long-lasting submucosal fluid cushions (SFC). Thus, there is a critical need for a material that is easy to inject while also maintaining a durable barrier. We prepared succinylated hydroxybutyl chitosan (HBC-SA) by adding succinic anhydride (SA) to hydroxybutyl chitosan (HBC). The hydrogel had excellent temperature-sensitive properties and was able to be injected via an endoscopic injection needle even after gel formation. In vitro and in vivo studies showed that it has satisfactory biocompatibility. Functional experiments showed that the submucosal lifting properties of this hydrogel were significantly better than that of normal saline (NS) and sodium hyaluronate (SH), two commonly used clinical materials. In addition, the hydrogel possessed excellent hemostatic properties. Based on these results, HBC-SA is a promising candidate for submucosal injection during ESD.

Research progress on biomass-based materials for oil/water separation: Designing strategy and efficiency mechanism

The treatment of water contaminated with oil or organic solvents has always been a thorny challenge, considering the complexity of water pollution, the susceptibility to secondary pollution and the consequent depletion of resources. Biomass is a versatile, green and self-circulating natural material that shows important potential in designing high-performance oil/water separation materials. This review highlights the recent research progress on biomass-based materials (BBMs) in the field of oil-water separation. Firstly, related properties for displaying definitions, sources and specificities on biomass materials are introduced, and the basic wetting theory of interfacial wettability is discussed. Secondly, representative nature-inspired designing strategies for oil-water separation materials are summarized. Finally, the current development prospects, future challenges and trends on BBM for oil-water separation are discussed as well. Hopefully, this review will provide some essential guidelines for the researchers to design novel oil/water separation materials with green, self-degradable, low-toxicity and readily available raw materials.

Influence of biopolymer-vegetation interaction on soil hydro-mechanical properties under climate change: A review

Soil reinforcement using eco-friendly biopolymer and vegetation has been increasingly popular in geotechnical engineering. However, research is still in its early stages due to complex biochemical interactions between biopolymers and plants. Moreover, under the increasing climate change, extreme weather poses severe challenges to the effectiveness of biopolymer-vegetation on soil treatment. Therefore, this paper provides a comprehensive review and summary of recent research on the influence of biopolymer and biopolymer-vegetation interaction on soil properties. First, this paper evaluates the various hydraulic and mechanical properties of soils after biopolymer treatment, including compaction characteristics, Atterberg limits, unconfined compressive strength, shear strength, tensile strength, permeability, water holding capacity, slaking behavior, and erosion resistance, as well as the influence of climate change. Then, the application of biopolymer-vegetation measure in the current field of soil treatment is summarized, and the biopolymer-vegetation interaction is discussed, including the influence of biopolymers on plant germination rate, growth conditions, wilting rate, and other indicators. Under drought and water scarcity conditions, biopolymers can improve soil mechanical strength and water retention, reducing plant wilting rate, and enhancing the survival ability of plants under extreme climate changes. Appropriate biopolymers can increase soil strength by >50 %, reduce strength and mass losses from dry-wet cycles to within 10 %, enhance grass seed germination rates by over 60 %, and reduce wilting rates under drought stress by 80 %. Finally, the research gaps and deficiencies in this field are highlighted, and potential research hotspots that can be strengthened and studied in the future are proposed. This review demonstrates the biopolymer-vegetation measure to be a new ecological restoration technology with widespread application prospects.

Marine polysaccharides for antibiofilm application: A focus on biomedical fields

Microbial pathogens such as bacteria and fungi form biofilms, which represent substantial hurdles in treating human illness owing to their adaptive resistance mechanism to conventional antibiotics. Biofilm may cause persistent infection in a variety of bodily areas, including wounds, oral cavity, and vaginal canal. Using invasive devices such as implants and catheters contributes significantly to developing healthcare-associated infections because they offer an ideal surface for biofilm formation. Marine organisms produce a variety of polysaccharides, which have recently attracted worldwide attention due to their biochemical features, various applications, and advantageous properties such as bioactivity, biodegradability, and biocompatibility. Because of their antimicrobial and antibiofilm features, several polysaccharides such as chitosan, fucoidan, carrageenan, alginate, and hyaluronic acid have been used to treat infected wounds as well as ophthalmic, oral, and vaginal infections. In addition, marine polysaccharides are currently employed as coatings on medical devices and implant materials, alone or in combination with other bioactive substances or nanomaterials, to protect the materials' undertones from microbial contamination. This review discussed the recent advancements in marine polysaccharides and their derivatives as a therapeutic potential against biofilm-associated diseases. The potential obstacles in the scalability of their production, clinical translation, and/or regulatory hurdles have also been discussed.

Production and simulated digestion of high-load beads containing Schizochytrium oil encapsulated utilizing prilling technique

The oil from the heterotroph Schizochytrium is a rich source of n-3 PUFA, particularly DHA, and therefore highly susceptible to oxidation. The present work reports the first application of coaxial prilling for the protection of this oil through microencapsulation. After process optimization, core-shell microparticles were produced with calcium or zinc alginate at different concentrations. Encapsulates were analyzed in their tocopherol and PUFA content. Prilling lowered the earlier but had little effect on the latter. Microcapsules coated with calcium alginate (1 % and 1.75 %) had higher oil load and encapsulation efficiency and were therefore submitted to in vitro digestion together with a simulated meal. Digesta were also analyzed with HPLC-qTOF and 1H NMR and compared to undigested encapsulates. While 1 % calcium shell granted lower oil release and protection from oxidation in the simulated gastrointestinal tract, chromatographic and spectroscopic data of digesta showed higher presence of lipid digestion products.

Fabrication of stable hydrogel microspheres with hydrophobic shell using water-in-water (W/W) Pickering emulsion template

Hydrogel microspheres are promising for food applications. The water-in-oil (W/O) emulsion template is commonly used to prepare the hydrogel microspheres. However, this method often involves synthetic surfactants and toxic organic solvents to remove the oil phase. The swelling problem of the resultant microspheres is another obstacle. In this study the water-in-water (W/W) emulsion template of gelatin-in-dextran was used to prepare the hydrogel microspheres, without the addition of surfactants, toxic reagents and high energy input. To prevent swelling, zein particles modified with alginate were served as a hydrophobic shell of the gelatin core. The formation evolution of these core-shell microspheres and its relevant factors including phase behavior of the immiscible gelatin/dextran, the binding of zein/alginate and the addition of the modified zein particles were investigated. It was found that small amount of alginate could induce zein particles to adsorb on the gelatin surface, whereas the excess led to adsorption competition. When using 0.6 wt% particles with zein/alginate ratio of 1:0.5, the ideal core-shell microspheres which were fully covered by the particles and with a self-supporting architecture in uniform size (18.8 ± 0.1 μm) and spherical shape were obtained. These microspheres showed remarkable stability under the conditions of heat treatment, varied pHs and salt concentrations and long-term storage either in refrigerator or room environment. Their sizes were easily manipulated by adjusting the concentration and molar mass of the biopolymers. It is believed that the desired stability and tunable sizes of these edible core-shell microspheres could contribute the development of their applications in foods.

Alginate sulfonamide hydrogel beads for 5-fluorouracil delivery: antitumor activity, cytotoxicity assessment, and theoretical investigation

This study focused on grafting a new monomer (E)-N-(4-(3-(4-bromophenyl) acryloyl) phenyl)-4-methyl benzene sulfonamide (Br-PS) onto sodium alginate (Alg) using a free radical polymerization method. The optimal parameters for the grafting polymerization reaction were investigated, including initiator and monomer concentrations, polymerization reaction duration, and temperature. Additionally, the conversion, graft, and solid content percentages were calculated. The resulting novel poly (Br-PS)-g-Alg was thoroughly analyzed using Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), and scanning electron microscopy (SEM). Moreover, poly (Br-PS)-g-Alg was tested for cytotoxicity and selectivity values on lung cancer cell line (A549), breast cancer cell line (MDA-MB-231), and a normal cell line (MDCK) using the neutral red uptake test. Poly (Br-PS)-g-Alg demonstrated more inhibitory impact (IC50 = 33.37 and 40.9 μg/mL) and high selectivity (selectivity index = 4.83 and 3.94) on the A549 and MDA-MB-231 cell lines, respectively. Furthermore, uniform beads of creative poly (Br-PS)-g-Alg were fabricated, and their swelling rate in various media was studied. These beads could potentially serve as drug carriers for 5-fluorouracil (5-FU). Release experiments in simulated gastric (SGF) and intestinal fluids (SIF) showed a slower 5-FU release pattern in SGF compared to SIF. The proposed structures of poly (Br-PS)-g-Alg were theoretically verified using density functional theory with DFT/B3LYP/6-31(G) basis set, revealing distinct interactions due to the presence of different functional groups. The findings of this study could significantly impact the development of new drug delivery systems.

Expanded Perlite-Reinforced Alginate Xerogels: A Chemical Approach to Sustainable Building and Packaging Materials

In sustainable construction and packaging, the development of novel bio-based materials is crucial, driving a re-evaluation of traditional components. Lightweight, biodegradable materials, including xerogels, have great potential in architectural and packaging applications. However, reinforcing these materials to improve their mechanical strength remains a challenge. Alginate is a promising matrix material that may be compatible with inorganic fibrous or particulate materials. In this study, biocomposite xerogel-structured foam materials based on an alginate matrix with expanded perlite reinforcement are improved using certain additives in different weight ratios. The plasticizers used include glycerol and gum arabic, while chitosan was added as an additional reinforcement, and iota carrageenan was added as a stabilizer. The tested specimens, with varying weight ratios of the added components, showed good mechanical behavior that highlights their potential use as packaging and/or architectural materials. The influence of the presence of different components in the composite material specimens on the modulus of elasticity was investigated using SEM images and FTIR analyses of the specimens. The results show that the specimen with the largest improvement in the elastic modulus contained a combination of chitosan and glycerol at a lower percentage (1.96 MPa), and the specimen with the largest improvement in tensile strength was the specimen containing chitosan with no plasticizers (120 kPa), compared to cases where combinations of other materials are present.

Gastrointestinal-inert prebiotic micro-composites improve the growth and community diversity of mucosal-associated bacteria

The process of microencapsulation and the development of microparticle-based drug formulations have gained increased pharmaceutical interest, particularly for drug delivery and bacterial-encapsulation purposes for probiotic delivery. Existing studies have examined microcomposite (MC) responses to gastrointestinal (GI) conditions with the aim of controlling disintegration, and thus release, across the small and large bowel. However, the delivery of MCs which remain intact, without degrading, could act as bacterial growth scaffolds or materials providing a prebiotic support, conferring potentially beneficial GI health properties. This present study employs prilling as a method to produce a portfolio of MCs using a variety of biopolymers (alginate, chitosan, pectin and gellan gum) with a range of MC diameters and density compositions. Fluorescent probes are co-encapsulated within each MC to enable flow-cytometry directed release profile assessments following exposure to chemical simulated gastric and intestinal digestion conditions. We observe that MC size, gel-strength, density, and biopolymer material all influence response to gastric and intestinal conditions. Gellan gum (GG) MCs demonstrated complete resistance to disintegration throughout GI-simulation in the stomach and small intestine. Considering these MCs could reach the colon intact, we then examined how such MCs, doped with prebiotic growth supporting carboxymethyl cellulose (CMC) polymers, could impact microbial communities using a bioreactor model of the colonic microbiome. Following supplementation with GGCMC MCs, mucosal bacterial diversity (using 16 s rRNA sequencing and Shannon entropy and observed feature diversity metrics) and taxonomic composition changes were observed. Concentrations of short chain fatty acid (SCFA) metabolites were also found to be altered. This is the first study to comprehensivelyexamine how MC physicochemistry can be manipulated to tailor MCs to have the desired GI release performance and subsequently, how GI-resistant MCs could have influential microbial altering properties and be adopted in novel prebiotic strategies.

Enhanced healing of burn wounds by multifunctional alginate-chitosan hydrogel enclosing silymarin and zinc ‎oxide ‎nanoparticles

Multifunctional wound dressings have been applied for burn injuries to avoid complications and promote tissue regeneration. In the present study, we fabricated a natural alginate-chitosan hydrogel comprising silymarin and green-synthesized zinc ‎oxide ‎nanoparticles (ZnO NPs). Then, the physicochemical attributes of ZnO NPs and loaded hydrogels were analyzed. Afterward, wound healing efficacy was evaluated in a rat model of full-thickness dermal burn wounds. The findings indicated that ZnO NPs were synthesized via reduction with phytochemicals from Elettaria cardamomum seeds extract. The microscopic images exhibited fairly spherical ZnO NPs (35-45 nm), and elemental analysis verified the relevant composition. The hydrogel, containing silymarin and biosynthesized ZnO NPs, displayed a uniform appearance, smooth surfaces, and a porous structure. Moreover, infrared spectroscopy ‎identified functional groups, confirming the successful loading without adverse interactions. The obtained hydrogel exhibited great water absorption, high porosity, sustainable degradation for several days, and enhanced antioxidant capability of the combined loaded component. In vivo studies revealed faster and superior wound healing, achieving nearly complete closure by day 21. Histopathology confirmed improved cell growth, tissue regeneration, collagen deposition, and neovascularization. It is believed that this multifunctional hydrogel-based wound dressing can be applied for effective burn wound treatment.

Advances and perspectives in use of semisolid formulations for photodynamic methods

Although nearly 30 years have passed since the introduction of the first clinically approved photosensitizer for photodynamic therapy, progress in developing new pharmaceutical formulations remains unsatisfactory. This review highlights that despite years of research, many recurring challenges and issues remain unresolved. The paper includes an analysis of selected essential studies involving aminolevulinic acid and its derivatives, as well as other photosensitizers with potential for development as medical products. Among various possible vehicles, special attention is given to gelatin, alginates, poly(ethylene oxide), polyacrylic acid, and chitosan. The focus is particularly on infectious and cancerous diseases. Key aspects of developing new semi-solid drug forms should prioritize the creation of easily manufacturable and biocompatible preparations for clinical use. At the same time, new formulations should preserve the primary function of photosensitizers, which is the generation of reactive oxygen species capable of destroying pathogenic cells or tumors. Additionally, the use of adjuvant properties of carriers, which can enhance the effectiveness of macrocycles, is emphasized, especially in chitosan-based antibacterial formulations. Current research indicates that many promising dyes and macrocyclic compounds with high potential as photosensitizers in photodynamic therapy remain unexplored in formulation and development work. This review outlines potential new and previously explored pathways for advancing photosensitizers as active pharmaceutical ingredients (APIs).

In the process of polysaccharide gel formation: A review of the role of competitive relationship between water and alcohol molecules

Polysaccharides have emerged as versatile materials capable of forming gels through diverse induction methods, with alcohol-induced polysaccharide gels demonstrating significant potential across food, medicinal, and other domains. The existing research mainly focused on the phenomena and mechanisms of alcohol-induced gel formation in specific polysaccharides. Therefore, this review provides a comprehensive overview of the intricate mechanisms underpinning alcohol-triggered gelation of different polysaccharides and surveys their prominent application potentials through rheological, mechanical, and other characterizations. The mechanism underlying the enhancement of polysaccharide network structures by alcohol is elucidated, where alcohol displaces water to establish hydrogen bonding and hydrophobic interactions with polysaccharide chains. Specifically, alcohols change the arrangement of water molecules, and the partial hydration shell surrounding polysaccharide molecules is disrupted, exposing polysaccharides' hydrophobic groups and enhancing hydrophobic interactions. Moreover, the pivotal influences of alcohol concentration and addition method on polysaccharide gelation kinetics are scrutinized, revealing nuanced dependencies such as the different gel-promoting capabilities of polyols versus monohydric alcohols and the critical threshold concentrations dictating gel formation. Notably, immersion of polysaccharide gels in alcohol augments gel strength, while direct alcohol addition to polysaccharide solutions precipitates gel formation. Future investigations are urged to unravel the intricate nexus between the mechanisms underpinning alcohol-induced polysaccharide gelation and their practical utility, thereby paving the path for tailored manipulation of environmental conditions to engineer bespoke alcohol-induced polysaccharide gels.

Sweet potato protein hydrolysates solidified calcium-induced alginate gel for enhancing the encapsulation efficiency and long-term stability of purple sweet potato anthocyanins in beads

Based on the previous research, this work aimed to reveal the effect of sweet potato protein hydrolysates (SPPHs) with different molecular weights (1000, 3000, and 8000 Da) at 0.5 % on the gelation behavior of calcium-induced sodium alginate (SA), and the encapsulation efficiency and storage stability of purple sweet potato anthocyanins (PSPA) in calcium-induced alginate gel beads was determined. Results indicated that SPPHs with a molecular weight of 8000 Da formed hydrogen bonds and other interactions with SA, which strengthened the internal network connections of the gel, significantly enhanced the gel and effectively filled its pores. The highest encapsulation efficiency was achieved at 87.27 %, compared to 61.73 % without SPPHs. Additionally, stored at 37 °C for 21 days after commercial sterilization, the residual concentration of PSPA with SPPHs was 2.50 times higher than that without SPPHs. SPPHs can enhance the encapsulation efficiency of PSPA and retard their release in gel beads.

Structure and Dynamics of Water in Polysaccharide (Alginate) Solutions and Gels Explained by the Core-Shell Model

In both biological and engineered systems, polysaccharides offer a means of establishing structural stiffness without altering the availability of water. Notable examples include the extracellular matrix of prokaryotes and eukaryotes, artificial skin grafts, drug delivery materials, and gels for water harvesting. Proper design and modeling of these systems require detailed understanding of the behavior of water confined in pores narrower than about 1 nm. We use molecular dynamics simulations to investigate the properties of water in solutions and gels of the polysaccharide alginate as a function of the water content and polymer cross-linking. We find that a detailed understanding of the nanoscale dynamics of water in alginate solutions and gels requires consideration of the discrete nature of water. However, we also find that the trends in tortuosity, permeability, dielectric constant, and shear viscosity can be adequately represented using the "core-shell" conceptual model that considers the confined fluid as a continuum.

Hydrogel System with Independent Tailoring of Mechanics, CT, and US Contrasts for Affordable Medical Phantoms

Medical phantoms mimic aspects of procedures like computed tomography (CT), ultrasound (US) imaging, and surgical practices. However, the materials for current commercial phantoms are expensive and the fabrication with these is complex and lacks versatility. Therefore, existing material solutions are not suitable for creating patient-specific phantoms. We present a novel and cost-effective material system (utilizing ubiquitous sodium alginate hydrogel and coconut fat) with independently and accurately tailorable CT, US, and mechanical properties. By varying the concentration of alginate, cross-linker, and coconut fat, the radiological parameters and the elastic modulus were adjusted independently in a wide range. The independence was demonstrated by creating phantoms with features hidden in US, while visible in CT imaging and vice versa. This system is particularly beneficial in resource-scarce areas since the materials are cheap (<$ 1 USD/kg) and easy to obtain, offering realistic and versatile phantoms to practice surgeries and ultimately enhance patient care.

Facile Construction of Flame-Resistant and Thermal-Insulating Sodium Alginate Aerogel Incorporating N- and P-Elements

In this study, sodium alginate (SA) aerogel cross-linked with Ca2+ was selected as the basic skeleton to construct a lightweight, flame retardant, and thermal insulating composite aerogel via modification with melamine and phytic acid. The resulting aerogel, SA-1.0 MP, achieved a thermal conductivity as low as 0.0379 W/(m·K). Compared to pristine SA aerogel, SA-1.0 MP demonstrated improved fire resistance, evidenced by a substantial increase in the limiting oxygen index (LOI) from 21.5% to 48.8% and a V-0 rating in the UL-94 test. Furthermore, a synergistic mechanism was proposed to explain its remarkable flame-retardant capability.

Optimization and characterization of brown seaweed alginate for antioxidant, anticancer, antimicrobial, and antiviral properties

Alginate is a natural polysaccharide obtained from brown seaweeds and having advantageous health usefulness, was employed extensively in nutraceutical sectors and the pharmaceutical industry. This research was devoted for optimization of alginate extraction from different brown seaweeds. A Box-Behnken Design (BBD) was used for the optimization of alginate extraction from Padina pavonica by analyzing the influence of temperature (30, 40, and 50 °C), time (60, 120, and 180 min), and alkaline concentration (1 %, 2 %, and 3 %) on extraction yield and uronic acid content. The optimal conditions recorded to maximize the alginate yield and its uronic content were an alkali concentration of 2.5 % and a temperature of 39.95 °C for 102.5 min. The optimized parameters achieved from BBD were used to compare alginate extraction from P. pavonica, Sargassum cinereum, Turbinaria turbinata, and Dictyota dichotoma. FTIR, 1H NMR, and HPLC were used to characterize the extracted alginate. The bioactivity of alginate against free radicals, breast cancer cells (MCF-7), some pathogenic microbes, and SARS-CoV-2 viruses was tested. Under the optimized conditions, alginate was extracted from P. pavonica at a rate of 21.13 ± 2.47 % DW, S. cinereum at 24.08 ± 0.33 % DW g/L, T. turbinata at 17.47 ± 0.26 % DW, and D. dichotoma at a rate of 19.57 ± 3.60 % DW. The alginate extracted from D. dichotoma showed the highest antioxidant, anticancer, and antiviral activity.

Biomedical potentials of alginate via physical, chemical, and biological modifications

Alginate is a linear polysaccharide with a modifiable structure and abundant functional groups, offers immense potential for tailoring diverse alginate-based materials to meet the demands of biomedical applications. Given the advancements in modification techniques, it is significant to analyze and summarize the modification of alginate by physical, chemical and biological methods. These approaches provide plentiful information on the preparation, characterization and application of alginate-based materials. Physical modification generally involves blending and physical crosslinking, while chemical modification relies on chemical reactions, mainly including acylation, sulfation, phosphorylation, carbodiimide coupling, nucleophilic substitution, graft copolymerization, terminal modification, and degradation. Chemical modified alginate contains chemically crosslinked alginate, grafted alginate and oligo-alginate. Biological modification associated with various enzymes to realize the hydrolysis or grafting. These diverse modifications hold great promise in fully harnessing the potential of alginate for its burgeoning biomedical applications in the future. In summary, this review provides a comprehensive discussion and summary of different modification methods applied to improve the properties of alginate while expanding its biomedical potentials.

Cell-Based Meat Scaffold Based on a 3D-Printed Starch-Based Gel

Starch was mixed with a gel to produce a starch-based gel ink, which exhibited favorable printing characteristics. Through the optimization of infill density, 3D-printed scaffolds with 50% infill density and a highly ordered microstructure were successfully fabricated. The addition of calcium carbonate nanoparticles-glucono delta lactone (CaCO3 NPs-GDL) had notable effects on the swelling degree, in vitro digestion, water stability, and pore distribution of the scaffolds. When the amount of CaCO3 NPs in the starch-based gel was 0.075 g, the resulting 3D-printed gel scaffold with a 50% infill density proved to be the most suitable for cultivating cell-based meat. It featured pore sizes ranging from 80 to 120 μm and a compression modulus of 246.76 Pa. After 7 days of proliferation, the C2C12 mouse skeletal myoblasts exhibited an approximately 2.81-fold increase in cell numbers. The fusion index and maturation index of C2C12 cells on the scaffolds were 57.00 ± 0.45% and 34.56 ± 0.56%, respectively. The starch-based gel scaffolds demonstrated excellent water stability and in vitro degradability. Moreover, C2C12 cells exhibited successful proliferation and differentiation on the starch-based scaffolds, ultimately leading to the production of cell-based meat. This study developed a starch-based composite gel scaffold for the manufacture of cell-based meat.

Injectable Tissue Adhesive Microgel Composite Containing Antifibrotic Drug for Vocal Fold Scarring

Vocal fold (VF) scarring, a complex problem in laryngology, results from injury and inflammation of the layered architecture of the VFs. The resultant voice hoarseness, for which successful therapeutic options are currently limited, affects the patient's quality of life. A promising strategy to reverse this disorder is the use of antifibrotic drugs. The present study proposes a novel microbead-embedded injectable hydrogel that can sustain the release of the anti-fibrotic drug pirfenidone (PFD) for vocal fold scarring. Microbeads were developed using sodium alginate and gelatin, which were further embedded into a biomimetic and tissue adhesive gellan gum (GG) hydrogel. The microbead-embedded hydrogel exhibited improved injectability, viscoelasticity, tissue adhesiveness, degradability, and swelling compared to the hydrogel without beads. Additionally, the bead-embedded hydrogel could sustain the release of the PFD for a week. In vitro studies showed that the drug-loaded hydrogel could reduce the migration and proliferation of fibroblast cells in a dose-dependent manner. In summary, this study demonstrates the potential of a PFD-loaded injectable hydrogel with enhanced viscoelastic and tissue-adhesive properties for vocal fold scarring applications.

Preparation of hyaluronic acid-loaded liquid-core hydrogel beads with acceptable mechanical properties and thermal stability

BACKGROUND

Hyaluronic acid liquid-core hydrogel beads (HA-LHB) is a good way for oral intake of HA. However, HA may affect the reaction-diffusion of sodium alginate (SA) and Ca2+ leading to poor mechanical properties, since HA is a polyanionic electrolyte having electrostatic effect and a certain spatial site-blocking effect.

RESULTS

The mechanical properties of HA-LHB were modified from bathing solution, core solution and secondary calcium bath time. The mechanical properties varied with the SA structure and concentration in bathing solution, where SA with high G (guluronic acid) segment compounded with SA with high M (mannuronic acid) segment at a mass ratio of 7:3 with a 11 g kg-1 concentration showed the best mechanical properties. The secondary calcium bath can greatly improve the mechanical properties due to the tight network formed by bidirectional crosslinking, and 15 min reaction reached the plateau if Ca2+ is sufficient. And the mechanical properties were positively correlated with calcium lactate concentration only at <70 g kg-1 in core solution, but the diffusion of Ca2+ was hindered by the tight gel network at higher concentrations. Moreover, the mechanical properties can be maintained during heat treatment, due to the rearrangement of alginate network structure.

CONCLUSION

Our results suggested that the problem of poor mechanical properties of LHB in the presence of high HA concentration can be avoided by process control, which may broaden the development of HA and popping boba market. © 2024 Society of Chemical Industry.

Exploring the impact of encapsulation on the stability and bioactivity of peptides extracted from botanical sources: trends and opportunities

Bioactive peptides derived from plant sources have gained significant attention for their potential use in preventing and treating chronic degenerative diseases. However, the efficacy of these peptides depends on their bioaccessibility, bioavailability, and stability. Encapsulation is a promising strategy for improving the therapeutic use of these compounds. It enhances their stability, prolongs their shelf life, protects them from degradation during digestion, and enables better release control by improving their bioaccessibility and bioavailability. This review aims to analyze the impact of various factors related to peptide encapsulation on their stability and release to enhance their biological activity. To achieve this, it is necessary to determine the composition and physicochemical properties of the capsule, which are influenced by the wall materials, encapsulation technique, and operating conditions. Furthermore, for peptide encapsulation, their charge, size, and hydrophobicity must be considered. Recent research has focused on the advancement of novel encapsulation methodologies that permit the formation of uniform capsules in terms of size and shape. In addition, it explores novel wall materials, including polysaccharides derived from unconventional sources, that allow the precise regulation of the rate at which peptides are released into the intestine.

Scalable and Versatile Metal Ion Solidificated Alginate Hydrogel for Skin Wound Infection Therapy

Bacterial infections in wounds continue to be a major challenge in clinical settings worldwide and represent a significant threat to human health. This work proposes novel expandable and versatile methods for solidifying sodium alginate (SA) with metal ions (such as Fe3+, Co2+, Ni2+, Cu2+, and Zn2+) to create Metal-Alginate (M-Alg) hydrogel with adjustable morphology, composition, and microstructure. It conforms to the wound site, protects against second infection, reduces inflammation, and promotes the healing of infected wounds. Among these hydrogels, Cu-Alginate (Cu-Alg) shows excellent sterilization effect and good efficacy against both gram-positive and gram-negative bacteria, including multidrug-resistant (MDR) strains such as Methicillin-resistant Staphylococcus aureus (MRSA) and Carbapenem-resistant Klebsiella pneumoniae (CRKP) due to its dual antibacterial mechanisms: contact-killing and reactive oxygen species (ROS) burst. Importantly, it exhibits low cytotoxicity and biodegradability. This simple and cost-effective gel-based system has the potential to introduce an innovative approach to the management of wound infection and offers promising new perspectives for the advancement of wound care practice.

Nano-enabled smart and functional materials toward human well-being and sustainable developments

Fabrication and operation on increasingly smaller dimensions have been highly integrated with the development of smart and functional materials, which are key to many technological innovations to meet economic and societal needs. Along with researchers worldwide, the Waterloo Institute for Nanotechnology (WIN) has long realized the synergetic interplays between nanotechnology and functional materials and designated 'Smart & Functional Materials' as one of its four major research themes. Thus far, WIN researchers have utilized the properties of smart polymers, nanoparticles, and nanocomposites to develop active materials, membranes, films, adhesives, coatings, and devices with novel and improved properties and capabilities. In this review article, we aim to highlight some of the recent developments on the subject, including our own research and key research literature, in the context of the UN Sustainability development goals.

The performance of microbial fuel cell with sodium alginate and super activated carbon composite gel modified anode

Microbial fuel cells (MFCs) have the functions of wastewater treatment and power generation. The incorporation of modified anodes enhances the sustainable power generation performance of MFCs. In this study, to evaluate the feasibility of sodium alginate (SA) as a biocompatible binder, hydrogel mixed with super activated carbon (SAC) and SA was modified the carbon cloth anode of MFC. The results showed that the maximum output voltage in the SAC/SA hydrogel modified anode MFC was 0.028 V, which was increased by 115%, compared with the blank carbon cloth anode. The internal resistance of MFC was 9429 Ω, which was 18% lower than that of control (11560 Ω). The maximum power density was 6.14 mW/m2, which was increased by 365% compared to the control. After modification of SAC/SA hydrogel, the chemical oxygen demand (COD) removal efficiency reached to 56.36% and was 12.72% higher than the control. Coulombic efficiency with modified anode MFC reached 17.65%, which was increased by 104%, compared with the control. Our findings demonstrate the feasibility of utilizing SA as a biocompatible binder for anode modification, thereby imparting sustainable and enhanced power generation performance to MFCs. This study presented a new selectivity for harnessing algal bioresources and improving anode binders in future MFC applications.

Molecular and cellular signalling pathways for promoting neural tissue growth - A tissue engineering approach

Neural tissue engineering is a sub-field of tissue engineering that develops neural tissue. Damaged central and peripheral nervous tissue can be fabricated with a suitable scaffold printed with biomaterials. These scaffolds promote cell growth, development, and migration, yet they vary according to the biomaterial and scaffold printing technique, which determine the physical and biochemical properties. The physical and biochemical properties of scaffolds stimulate diverse signalling pathways, such as Wnt, NOTCH, Hedgehog, and ion channels- mediated pathways to promote neuron migration, elongation and migration. However, neurotransmitters like dopamine, acetylcholine, gamma amino butyric acid, and other signalling molecules are critical in neural tissue engineering to tissue fabrication. Thus, this review focuses on neural tissue regeneration with a tissue engineering approach highlighting the signalling pathways. Further, it explores the interaction of the scaffolds with the signalling pathways for generating neural tissue.

Varying ratios of M/G in alginate to modulate macrophages polarization and its application for wound healing in diabetic

Alginate (SA) comprises repeating unis of β-1, 4 linked β-D-mannuronic acid (M) and α-L-guloronic acid (G) in varying proportions. The M/G ratio greatly impacts its anti-inflammatory properties in tissue healing wound, as less knowledge reported. This study examined the performances of both SA and SA hydrogel crosslinked with copper ions (SA-Cu) with different M/G ratios are studied. SA with higher M/G ratios stimulated macrophage migration and shifted from M0 to the pro-inflammatory Ml phenotype, while lower M/G ratios shifted from M1 to the pro-repair M2 phenotype. Furthermore, SA-Cu hydrogels with lower M/G ratios exhibited enhanced cross-linking degree, mechanical and rheological properties, as well Cu releasing rate. The reason may be attributed to a relative easy binding between Cu ions and G unit among Cu ions, M unit and G unit. In vitro cell evaluation showed that SA-Cu hydrogel with M/G ratio of 1:1 activated M2 macrophages and up-regulated anti-inflammatory cytokines expression more effectively than those of SA-Cu ratios (2:1) and (1:2). In vivo, SA-Cu hydrogel with M/G ratio of 1:1 expedited diabetic wound healing, accelerating infiltration and phenotype shift of M2 macrophages, and enhancing anti-inflammatory factors, epithelialization and collagen deposition in healing phases. This research highlights the significant role of M/G ratios in SA materials in influencing macrophage behavior and inflammatory responses, which would benefit its application field.

Insights on updates in sodium alginate/MXenes composites as the designer matrix for various applications: A review

Advancements in two-dimensional materials, particularly MXenes, have spurred the development of innovative composites through their integration with natural polymers such as sodium alginate (SA). Mxenes exhibit a broad specific surface area, excellent electrical conductivity, and an abundance of surface terminations, which can be combined with SA to maximize the synergistic effect of the materials. This article provides a comprehensive review of state-of-the-art techniques in the fabrication of SA/MXene composites, analyzing the resulting structural and functional enhancements with a specific focus on advancing the design of these composites for practical applications. A detailed exploration of SA/MXene composites is provided, highlighting their utility in various sectors, such as wearable electronics, wastewater treatment, biomedical applications, and electromagnetic interference (EMI) shielding. The review identifies the unique advantages conferred by incorporating MXene in these composites, examines the current challenges, and proposes future research directions to understand and optimize these promising materials thoroughly. The remarkable properties of MXenes are emphasized as crucial for advancing the performance of SA-based composites, indicating significant potential for developing high-performance composite materials.

Physicochemical properties and fractal characterizations of the functionalized porous clinoptilolites for controlling alginate delivery in growing cauliflower and leaf mustard

Using natural clinoptilolite (NCP) as a carrier and alginate (Alg)-calcium as an active species, the porous silicon calcium alginate nanocomposite (Alg-Ca-NCP) was successfully fabricated via adsorption-covalence-hydrogen bond. Its structural features and physicochemical properties were detailed investigated by various characterizations. The results indicated that Alg-Ca-NCP presented the disordered lamellar structures with approximately uniform particles in size of 300-500 nm. Specially, their surface fractal evolutions between the irregular roughness and dense structures were demonstrated via the SAXS patterns. The results elucidated that the abundant micropores of NCP were beneficial for unrestricted diffusing of Alg-Ca, which was conducive to facilitate a higher loading and sustainable releasing. The Ca content of leaf mustard treated with Alg-Ca-NCP-0.5 was 484.5 mg/100g on the 21st day, higher than that by water (CK) and CaCl2 solution treatments, respectively. Meanwhile, the prepared Alg-Ca-NCPs presented the obvious anti-aging effects on peroxidase drought stress of mustard leaves. These demonstrations provided a simple and effective method to synthesize Alg-Ca-NCPs as delivery nanocomposites, which is useful to improve the weak absorption and low utilization of calcium alginate by plants.

Development of interpenetrating network hydrogels: Enhancing the release and bioaccessibility of green tea polyphenols

Green Tea polyphenols (GTP) are important bioactive compounds with excellent physiological regulation functions. However, they are easily destroyed by the gastric environment during digestion. In this work, a sodium alginate (SA)-gellan gum (GG) interpenetrating network (IPN) hydrogel was synthesized to protect and delivery GTP. The ratio of SA/GG significantly affects the network structure of IPN hydrogels and the performance of delivering GTP. The hydrogel formed by interpenetrating 20 % GG with 80 % SA as the main network had the highest water uptake (55 g/g), holding capacity (950 mg/g), and freeze-thaw stability, with springiness reaching 0.933 and hardness reaching 1300 g, which due to the filling effect and non-covalent interaction. Rheological tests showed that the crosslink density of IPN hydrogel in SA-dominated network was improved by the addition of GG to make it better bound to GTP, and the higher water uptake meant that the system could absorb more GTP-containing solution. This IPN hydrogel maintained 917.3 mg/g encapsulation efficiency at the highest loading capacity (1080 mg/g) in tests as delivery system. In in vitro digestion simulations, owing to the pH responsiveness, the IPN hydrogel reduced the loss of GTP in gastric fluid, achieving a bioaccessibility of 71.6 % in the intestinal tract.

Covalent organic framework-sodium alginate-Ca2+-polyacrylic acid composite beads for convenient dispersive solid-phase extraction of neonicotinoid insecticides in fruit and vegetables

Neonicotinoids, the fastest-growing class of insecticides, have posed a multi-media residue problem with adverse effects on environment, biodiversity and human health. Herein, covalent organic framework-sodium alginate-Ca2+-polyacrylic acid composite beads (CACPs), facilely prepared at room temperature, were used in convenient dispersive solid-phase extraction (dSPE) and combined with high-performance liquid chromatography (HPLC) for the detection of five neonicotinoid insecticides (thiamethoxam, acetamiprid, dinotefuran, clothianidin, imidacloprid). CACPs can be completely separated within 1 min without centrifugation. After seven adsorption/desorption cycles, it maintained high extraction efficiencies (>90%). The developed method exhibited a wide linear range (0.01 ∼ 10 μg mL-1), low limits of detection (LODs, 0.0028 ∼ 0.0031 mg kg-1), and good repeatability (RSD ≤ 8.11%, n = 3). Moreover, it was applied to the determination of five neonicotinoids in fruit and vegetables (peach, pear, lettuce, cucumber, tomato), and recoveries ranged from 73.6% to 116.2%.

New insight into the mechanism of biofouling-resistant thiazole-linked covalent organic frameworks for selective uranium capture from seawater

The extraction of uranium from seawater is crucial for the sustainable production of nuclear fuel. Traditional amidoxime-functionalized adsorbents suffer from competitive adsorption of vanadium ion and biofouling. These challenges motivate the development of novel adsorbents for selective uranium extraction from seawater. Herein, four kinds of thiazole-linked covalent organic frameworks (COFs) were investigated to harvest uranium from seawater. The selectivity and anti-biofouling performance were systematically investigated through the molecular dynamics (MD) simulations. Driven by the pore size sieving effect and electrostatic interaction, the Ca2UO2(CO3)3 complex and vanadate anions were selectively separated by different COFs in special areas. On one hand, benefits from the small steric partition factor, the Ca2UO2(CO3)3 complex can stick on the surface of COFs. On the other hand, the dispersive negatively and positively charged areas of studied COFs work as potential binding sites for the Ca2UO2(CO3)3 complex and vanadate anions, respectively. Moreover, an analysis of pulling force and desorption time between uranium and vanadium ions further confirmed the selectivity of various thiazole-linked COFs. The anti-biofouling property was comparatively investigated by dynamic trajectory and solvent accessible surface area. Our outcomes illustrate that the hydroxyl and zwitterionic groups in the thiazole-linked COFs endow their strong surface hydrations to resist marine biofouling. In particular, the TpBdsaPa is identified as a promising candidate due to charge dispersed zwitterionic group as well as remarkable anti-biofouling ability. The present study sheds an atomic-level understanding of the thiazole-linked COFs for selective uranium uptaking from seawater, which will provide aid to design novel adsorbent with highly selective uranium extraction capacity and strong anti-biofouling property.

Recent advances in alginate-based composite gel spheres for removal of heavy metals

The discharge of heavy metal ions from industrial wastewater into natural water bodies is a consequence of global industrialisation. Due to their high toxicity and resistance to degradation, these heavy metal ions pose a substantial threat to human health as they accumulate and amplify. Alginate-based composite gels exhibit good adsorption and mechanical properties, excellent biodegradability, and non-toxicity, making them environmentally friendly heavy metal ion adsorbents for water with promising development prospects. This paper introduces the basic properties, cross-linking methods, synthetic approaches, modification methods, and manufacturing techniques of alginate-based composite gels. The adsorption properties and mechanical strength of these gels can be enhanced through surface modification, multi-component mixing, and embedding. The main production processes involved are sol-gel and cross-linking methods. Additionally, this paper reviews various applications of alginate composite gels for common heavy metals, rare earth elements, and radionuclides and elucidates the adsorption mechanism of alginate composite gels. This study aimed to provide a reference for synthesising new, efficient, and environmentally friendly alginate-based adsorbents and to contribute new ideas and directions for addressing the issue of heavy metal pollution.

Quaternary ammonium carboxymethyl chitosan composite hydrogel with efficient antibacterial and antioxidant properties for promoting wound healing

Multifunctional hydrogels have been developed to meet the various requirements of wound healing. Herein, an innovative hydrogel (QCMC-HA-PEG) was formed through the Schiff base reaction, composed of quaternary ammonium-modified carboxymethyl chitosan (QCMC), hyaluronic acid (HA), and 8-arms Polyethylene Glycol aldehyde (8-ARM-PEG-CHO). The resulting hydrogels exhibited good mechanical and adhesive properties with improved antibacterial efficacy against both Gram-positive and Gram-negative bacteria compared to CMC hydrogels. QCMC-HA-PEG hydrogels demonstrated remarkable adhesive ability in lap-shear test. Furthermore, the incorporation of MnO2 nanosheets into the hydrogel significantly enhanced its reactive oxygen species (ROS) scavenging and oxygen generation capabilities. Finally, experimental results from a full-thickness skin wound model revealed that the QCMC-HA-PEG@MnO2 hydrogel promoted skin epithelization, collagen deposition, and inflammatory regulation significantly accelerated the wound healing process. Therefore, QCMC-HA-PEG@MnO2 hydrogel could be a promising wound dressing to promote wound healing.

Measuring mechanical cues for modeling the stromal matrix in 3D cell cultures

A breast-cancer tumor develops within a stroma, a tissue where a complex extracellular matrix surrounds cells, mediating the cancer progression through biomechanical and -chemical cues. Current materials partially mimic the stromal matrix in 3D cell cultures but methods for measuring the mechanical properties of the matrix at cell-relevant-length scales and stromal-stiffness levels are lacking. Here, to address this gap, we developed a characterization approach that employs probe-based microrheometry and Bayesian modeling to quantify length-scale-dependent mechanics and mechanical heterogeneity as in the stromal matrix. We examined the interpenetrating network (IPN) composed of alginate scaffolds (for adjusting mechanics) and type-1 collagen (a stromal-matrix constituent). We analyzed viscoelasticity: absolute-shear moduli (stiffness/elasticity) and phase angles (viscous and elastic characteristics). We determined the relationship between microrheometry and rheometry information. Microrheometry reveals lower stiffness at cell-relevant scales, compared to macroscale rheometry, with dependency on the length scale (10 to 100 μm). These data show increasing IPN stiffness with crosslinking until saturation (≃15 mM of Ca2+). Furthermore, we report that IPN stiffness can be adjusted by modulating collagen concentration and interconnectivity (by polymerization temperature). The IPNs are heterogeneous structurally (in SEM) and mechanically. Interestingly, increased alginate crosslinking changes IPN heterogeneity in stiffness but not in phase angle, until the saturation. In contrast, such changes are undetectable in alginate scaffolds. Our nonlinear viscoelasticity analysis at tumor-cell-exerted strains shows that only the softer IPNs stiffen with strain, like the stromal-collagen constituent. In summary, our approach can quantify the stromal-matrix-related viscoelasticity and is likely applicable to other materials in 3D culture.