In situ crosslinkable multi-functional and cell-responsive alginate 3D matrix via thiol-maleimide click chemistry

In vivo, cells interact with the extracellular matrix (ECM), which provides a multitude of biophysical and biochemical signals that modulate cellular behavior. Inspired by this, we explored a new methodology to develop a more physiomimetic polysaccharide-based matrix for 3D cell culture. Maleimide-modified alginate (AlgM) derivatives were successfully synthesized using DMTMM to activate carboxylic groups. Thiol-terminated cell-adhesion peptides were tethered to the hydrogel network to promote integrin binding. Rapid and efficient in situ hydrogel formation was promoted by thiol-Michael addition "click" chemistry via maleimide reaction with thiol-flanked protease-sensitive peptides. Alginate derivatives were further ionically crosslinked by divalent ions present in the medium, which led to greater stability and allowed longer cell culture periods. By tailoring alginate's biofunctionality we improved cell-cell and cell-matrix interactions, providing an ECM-like 3D microenvironment. We were able to systematically and independently vary biochemical and biophysical parameters to elicit specific cell responses, creating custom-made 3D matrices. DMTMM-mediated maleimide incorporation is a promising approach to synthesizing AlgM derivatives that can be leveraged to produce ECM-like matrices for a broad range of applications, from in vitro tissue modeling to tissue regeneration.

Injectable hydrogels based on alginates grafted with LCST side-chains of different chemistry

A homologous series of thermoassociating copolymers was prepared by grafting onto alginates different amounts of three different temperature responsive polymers: poly(N-isopropylacrylamide), poly(di(ethylene glycol)methacrylate) and poly(ethylene oxide-co-propylene oxide). From a large set of analytical techniques combining rheology, calorimetry, NMR and SAXS, the relevant parameters controlling the sol/gel transition and the gel properties, mainly the degree of entanglement of macromolecules and the fraction of responsive stickers, were highlighted and interpreted objectively by considering the particularities of the phase diagrams of LCST polymers. Complementary analyses were implemented to investigate adhesiveness, injectabilty, gel swelling and molecular release in physiological environment of thermogelling formulations. In particular, it is shown that steady shear experiments allow to predict the injection forces by taking into account the characteristics of the system (syringe and needle), and that the rapid gelation of the formulations when they are heated at 37 °C delays the release of small molecules into the environment. The overall set of data is discussed in the framework of scaling relations in order to draw quantitative guidelines for the design of injectable thermoresponsive hydrogels.

Rapid visual detection of sulfur dioxide residues in food using acid-sensitive CdTe quantum dots-loaded alginate hydrogel beads

Acid-sensitive CdTe quantum dots-loaded alginate hydrogel (CdTe QDs-AH) beads were designed for the visual detection of SO2 residues. As proof of concept, two types of CdTe QDs were selected as model probes and embedded in AH beads. The entire test was performed within 25 min in a modified double-layer test tube with one bead fixed above the sample solution. Adding citric acid and heating at 70 ℃ for 20 min transformed the sulfites in the solution into SO2 gas, which then quenched the fluorescence of the CdTe QDs-AH beads. Using this assay, qualitative, naked-eye detection of SO2 residues was achieved in the concentration range of 25-300 ppm, as well as precise quantification was possible based on the difference in the average fluorescence brightness of the beads before and after the reaction. Five food types were successfully analysed using this method, which is simpler and more economical than existing methods, and does not require complex pretreatment.

Gluing blood into adhesive gel by oppositely charged polysaccharide dry powder inspired by fibrin fibers coagulation mediator

Hemostatic powders that adapt to irregularly shaped wounds, allowing for easy application and stable storage, have gained popularity for first-aid hemorrhage control. However, traditional powders often provide weak thrombus support and exhibit limited tissue adhesion, making them susceptible to dislodgment by the bloodstream. Inspired by fibrin fibers coagulation mediator, we have developed a bi-component hemostatic powder composed of positively charged quaternized chitosan (QCS) and negatively charged catechol-modified alginate (Cat-SA). Upon application to the wound, the bi-component powders (QCS/Cat-SA) rapidly absorb plasma and dissolve into chains. These chains interact with each other to form a network, which can effectively bind and entraps clustered red blood cells and platelets, ultimately leading to the creation of a durable and robust thrombus. Significantly, these interconnected polymers adhere to the injury site, offering protection against thrombus disruption caused by the bloodstream. Benefiting from these synthetic properties, QCS/Cat-SA demonstrates superior hemostatic performance compared to commercial hemostatic powders like Celox™ in both arterial injuries and non-compressible liver puncture wounds. Importantly, QCS/Cat-SA exhibits excellent antibacterial activity, cytocompatibility, and hemocompatibility. These advantages of QCS/Cat-SA, including strong blood clotting, wet tissue adherence, antibacterial activity, biosafety, ease of use, and stable storage, make it a promising hemostatic agent for emergency situations.

Optimization of hydrolysis conditions of alginate based on high performance liquid chromatography

Alginate is the most abundant polysaccharide compound in brown algae, which is widely used in various fields. At present, the determination of the content of alginate is mostly carried out using sulfuric acid and trifluoroacetic acid hydrolysis followed by the determination of the content, but the results are not satisfactory, and there are problems such as low hydrolysis degree and low recovery rate. Therefore, in this study, based on the optimization of high performance liquid chromatographic conditions for pre-column derivatization of 1-phenyl-3-methyl-5-pyrazolone (PMP), the hydrolysis effects of sulfuric acid, trifluoroacetic acid (TFA), oxalic acid, and formic acid were compared and the hydrolysis conditions were optimized. The results showed that formic acid was the best hydrolyzing acid. The optimal hydrolysis conditions were 95 % formic acid at 110 °C for 10 h. The hydrolysis effect was stable, with high recovery and low destruction of monosaccharides, which made it possible to introduce formic acid into the subsequent polysaccharide hydrolysis. The pre-column derivatization high performance liquid chromatography method established in this study was accurate and reliable, and the hydrolysis acid with better effect was screened, which provided a theoretical basis for the subsequent determination of alginate content.

Carrageenan/calcium alginate composite hydrogel filtration membranes for efficient cationic dye separation

The development of biopolymer-based filtration systems for water remediation applications is an extremely fascinating area of research. In this paper, we developed a biopolymer-based filtration system using sodium alginate (NaAlg) and carrageenan (Car) for the removal of the toxic cationic dye, methylene blue (MB). The membrane's properties were assessed using FTIR, TGA, UTM, FESEM, EDS, XRD, and water uptake, revealing commendable thermomechanical stability (5.79 MPa), good hydrophilicity, and compatibility. The experimental results further revealed that lambda Car/calcium alginate (λ-Car/CaAlg) exhibited superior dye rejection (100 %) and flux (11.67 L m-2 h-1) compared to kappa Car/CaAlg (κ-Car/CaAlg) (99.22 % and 11.19 L m-2 h-1) and plain alginate (CaAlg) (99.63 % and 9.79 L m-2 h-1). The high MB rejection rate was attributed to the sieving mechanism and electrostatic interaction. A rejection rate of 100 % was achieved at an initial MB concentration of 10 mg/L, pressure of 0.1 MPa, pH of 7, and temperature of 25 °C. Furthermore, the hydrogel membranes demonstrated excellent recyclability over nine cycles, indicating their potential for water treatment applications.

Development and testing of alginate/C3N4porphyrin bead as a self-initiated Fenton photocatalyst for highly efficient atrazine removal

Fenton reaction has been widely used for the efficient treatment of organic wastewater. However, its applications are limited by such key factors as a requirement of a workable pH < 3. In this study, we developed, tested, and optimized the alginate/C3N4porphyrin bead (alginate/C3N4por) as a recyclable photocatalyst in a photocatalysis-self-Fenton process to overcome these limitations. Porphyrin-modified C3N4 (C3N4por) was used as an H2O2 donator, while Fe(III) nodes served as a Fenton reagent. The as-prepared floating alginate/C3N4por bead utilized the light source as a driving force for the catalysis. Under visible light irradiation for 6 h, the model pollutant atrazine was degraded by 70.96 %, demonstrating better photocatalytic performance than alginate/C3N4 beads. This improvement was attributed to the higher H2O2 yield of C3N4por. The alginate/C3N4por bead showed better photocatalytic activity even after four consecutive cycles and could easily be recovered for reuse. Furthermore, Fe(III)/Ca(II) bimetallic alginate bead exhibited better photocatalytic activity and a higher content of •OH radicals than the Ca(II) monometallic alginate beads, due to the ability of Fe(III) nodes to serve as a Fenton reagent. The influences of light sources, and commonly existing matters (namely SO42-, Cl-, CO32-, NO3-, and humic acid) were investigated. Moreover, the alginate/C3N4por bead demonstrated good photocatalytic performance in a simulated natural environment without the addition of extra H2O2, with an atrazine removal percentage of up to 96.3 % after 3-h irradiation. These findings indicated the great potential of alginate/C3N4por beads in practical applications.

Innovative method for producing plant-based meat analogs: Acid/calcium-induced internal gelation of potato protein/alginate composites

When creating plant-based meat analogs, it is often challenging to mimic the structural and textural attributes of real meat products during the cooking process. In this study, we investigated the potential of using potato protein/calcium alginate composite gels to formulate plant-based meat analogs. These gels provide a semi-solid texture at ambient temperature that remains intact during cooking because the electrostatic crosslinks are resistant to heat. Composite gels consisting of potato protein (10 wt%) and alginate (0-2 wt%) were prepared using the internal gelation method. This method involves dispersing an insoluble form of calcium (CaHPO4) throughout the protein-polysaccharide matrix and then using glucono-delta-lactone (GDL) to slowly lower the pH, thereby releasing the Ca2+ ions evenly throughout the system. The calcium alginate increased the strength of the potato protein gels and provided structural resistance to heat. Appreciable water loss occurred during cooking for simple calcium alginate gels, but this was prevented when potato proteins were present. Increasing the alginate concentration from 0 to 1.5 % increased the strength of the composite gels but higher levels promoted phase separation and network disruption, which reduced the gel strength. Heating did not appreciably alter the microstructure of the composite gels, but it did alter that of the pure potato protein gels. Finally, the potential of the composite gels as plant-based meat analogs was assessed by comparing their thermal denaturation and textural properties to those of real chicken breast. The potato protein/alginate composites were shown to simulate the thermal denaturation and textural changes of real chicken during the cooking process. Overall, our results suggest that calcium alginate gels may be useful in the formulation of plant-based meat products with improved cooking properties.

A cross-linked macropore hydrogel based on M1 macrophage lysate and alginate regulates tumor-associated macrophages for the treatment of melanoma

Pro-inflammatory M1 macrophages possess the ability to change the immunosuppressive tumor microenvironment by releasing various inflammatory factors simultaneously, which can effectively inhibit tumor progression and relapse. Promoting macrophage polarization towards M1 may be an effective way to treat Melanoma. However, the risk of cytokine storm caused by the proliferation and excessive activation of M1 macrophages greatly limits it as a biosafety therapeutic strategy in anti-tumor immunotherapy. Therefore, how to engineer natural M1 macrophage to a biocompatible biomaterial that maintains the duration time of tumor suppressive property duration time still remains a huge challenge. To achieve this goal, we developed an injectable macroporous hydrogel (M1LMHA) using natural M1 macrophage lysates and alginate as raw materials. M1LMHA had excellent biocompatibility, adjustable degradation rate and could sustainably release varieties of natural inflammatory factors, such as tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), and interleukin-12 (IL-12), etc. M1LMHA could repolarize anti-inflammatory M2 macrophages to M1 macrophages by the synergistic effect of released tiny inflammatory factors via the NF-κB pathway. This study supported that M1LMHA might be an effective and safe tool to activate tumor-associated immune cells, improving the efficiency of anti-tumor immunotherapy.

Effects of radiation dose and dose rate on alginate and the use of radiation degraded alginate for peanut

Aqueous solutions of alginate (4 %) with or without hydrogen peroxide (0-2 % H2O2) were irradiated under a gamma Co-60 source. The effect of dose rate on the radiation scission yield (Gs) of resulting irradiated alginate was determined. At the dose of 20 kGy, the G(s) value of irradiated alginate decreased with the increase dose rate, suggesting that the irradiation at a suitable dose rate could further improve the radiation chemical yield of degradation. For the alginate irradiated at the same dose rate, G(s) value increased with the increase of H2O2 concentration. Average molecular weight (Mw) and polydispersity index (PI) of irradiated alginate rapidly decreased with the increase in dose and further decreased by addition of H2O2. The oligoalginate with Mw ~ 9800 g/mol was obtained by radiation degradation of 4 % alginate solution containing 2 % H2O2 at dose of 20 kGy. Radiation scission of glycoside bonds and formation of carbonyl groups (C=O) were indicated in UV and FTIR spectra of irradiated alginate. Peanut seedlings were fertilized with alginate and oligoalginate solutions, and the results showed that all growth parameters of the treated plants were better than those of the control. Furthermore, the oligoalginate prepared by gamma irradiation can be applied as a plant growth promoter for agriculture production.

Nanofibrous polyelectrolyte complex incorporated BSA-alginate composite bioink for 3D bioprinting of bone mimicking constructs

Although several bioinks have been developed for 3D bioprinting applications, the lack of optimal printability, mechanical properties, and adequate cell response has limited their practical applicability. Therefore, this work reports the development of a composite bioink consisting of bovine serum albumin (BSA), alginate, and self-assembled nanofibrous polyelectrolyte complex aggregates of gelatin and chitosan (PEC-GC). The nanofibrous PEC-GC aggregates were prepared and incorporated into the bioink in varying concentrations (0 % to 3 %). The bioink samples were bioprinted and crosslinked post-printing by calcium chloride. The average nanofiber diameter of PEC-GC was 62 ± 15 nm. It was demonstrated that PEC-GC improves the printability and cellular adhesion of the developed bioink and modulates the swelling ratio, degradation rate, and mechanical properties of the fabricated scaffold. The in vitro results revealed that the bioink with 2 % PEC-GC had the best post-printing cell viability of the encapsulated MG63 osteosarcoma cells and well oragnized stress fibers, indicating enhanced cell adhesion. The cell viability was >90 %, as observed from the MTT assay. The composite bioink also showed osteogenic potential, as confirmed by the estimation of alkaline phosphatase activity and collagen synthesis assay. This study successfully fabricated a high-shape fidelity bioink with potential in bone tissue engineering.

Enhancing effect on postharvest quality of potatoes through combined treatment of edible coating with UV-C irradiation

Various edible polymers [sodium alginate, carboxyl methylcellulose, sodium oleate, liquid paraffin, pectin, pullulan, polyvinyl acetate, and shellac (SHE)] as potato-coating materials and their effect on extending the shelf life of potatoes when combined with an edible coating and UV-C irradiation treatments were evaluated. As a result of the characterization of the edible polymers, SHE was selected as the optimal coating material because it had the best moisture and light barrier properties. SHE coating successfully prevented the greening, respiration, and sprouting of potatoes caused by exposure to light and oxygen. Additionally, it reduced weight loss by inhibiting transpiration on the potato surface. While the SHE coating did not exhibit antimicrobial effects, a significant effect was observed when combined with UV-C irradiation. This study suggests the potential of combined treatment of SHE coating and UV-C irradiation in extending the postharvest quality of potatoes.

Development of alginate-collagen interpenetrating network for osteoarthritic cartilage by in situ softening

This study presents an alginate-collagen interpenetrating network (IPN) matrix of incorporating collagen fibrils into an alginate hydrogel by physical mixing and controlled gelation. The resulting matrix closely mimics the physiological and pathological stiffness range of the chondrocyte pericellular matrix (PCM). Chondrocytes were cultured within three-dimensional (3D) alginate-collagen IPN matrices with varying stiffness, namely Firm, Medium, and Soft. Alginate lyase was introduced to study the effects of the changes in stiffness of the Firm on chondrocyte response by in situ softening. The developed alginate-collagen IPN matrix displayed good cell-biocompatibility. Compared with stiffer tissue culture plastic (TCP), chondrocytes grown within Firm displayed a stabilized differentiated phenotype characterized by higher expression levels of aggrecan, collagen II, and SOX-9. Moreover, the developed alginate-collagen IPN matrix exhibited a gradually increased percentage of propidium iodide (PI)-positive dead cells with decreasing stiffness. Softer matrices directed cells towards higher proliferation rates and spherical morphologies while stimulating chondrocyte cluster formation. Furthermore, reducing Firm stiffness by in situ softening decreased aggrecan expression, contributing to matrix degradation similar to that seen in osteoarthritis (OA). Hence, the 3D alginate-collagen IPN constructs hold significant potential for in vitro replicating PCM stiffness changes observed in OA cartilage.

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.

Construction of Fu brick tea polysaccharide-cold plasma modified alginate microgels for probiotic delivery: Enhancing viability and colonization

Emerging food processing technologies provide broader avenues for enhancing probiotic delivery systems. In this study, the new Fu brick tea polysaccharide (FBTP) was extracted and combined with cold plasma-modified alginate nano-montmorillonite (AMT) to prepare microgels by ionic gelation to improve the viability of encapsulated Lactobacillus kefiranofaciens JKSP109. Results showed that cold plasma treatment for 3 min changed the surface charge of AMT biopolymer solution, and FBTP addition reduced the particle size to the lowest of 223 ± 5.50 nm. Morphological analysis showed that the AMT treated with cold plasma for 3 min and FBTP (C3AMT + FBTP) formed a dense microgel through electrostatic interaction, and the probiotics were randomly distributed in their internal polysaccharide network, as well as the interlayer and surrounding of nanoparticles. The probiotics immobilized in C3AMT + FBTP microgel exhibited the highest viability (8.48 ± 0.03 log CFU/g) and colonic colonization after exposure to simulated gastrointestinal conditions. In addition, the good antioxidant activity of FBTP reduced the loss of probiotic viability during storage, with only 2.58 log CFU/g decreased after 4 weeks. Therefore, such probiotic products enriched with natural bioactive ingredients can be developed as a potential functional food additive.

On the performance of Sargassum-derived calcium alginate ion exchange resins for Pb2+ adsorption: batch and packed bed applications

Driven by climate change and human activity, Sargassum blooming rates have intensified, producing copious amount of the invasive, pelagic seaweed across the Caribbean and Latin America. Battery recycling and lead-smelter wastes have heavily polluted the environment and resulted in acute lead poisoning in children through widespread heavy metal contamination particular in East Trinidad. Our study details a comprehensive investigation into the use of Sargassum (S. natans), as a potential resource-circular feedstock for the synthesis of calcium alginate beads utilized in heavy metal adsorption, both in batch and column experiments. Here, ionic cross-linking of extracted sodium alginate with calcium chloride was utilized to create functional ion-exchange beads. Given the low quality of alginates extracted from Sargassum which produce poor morphological beads, composite beads in conjunction with graphene oxide and acrylamide were used to improve fabrication. Stand-alone calcium alginate beads exhibited superior Pb2+ adsorption, with a capacity of 213 mg g-1 at 20 °C and pH 3.5, surpassing composite and commercial resins. Additives like acrylamide and graphene oxide in composite alginate resins led to a 21-40% decrease in Pb2+ adsorption due to reduced active sites. Column operations confirmed Alginate systems' practicality, with 20-24% longer operating times, 15 times lower adsorbent mass on scale-up and 206% smaller column diameters compared to commercial counterparts. Ultimately, this study advocates for Sargassum-based Alginate ion-exchange beads as a bio-based alternative in Trinidad and developing nations for dealing with heavy metal ion waste, offering superior heavy metal adsorption performance and supporting resource circularity.

Development of a flow-cell bioreactor for immobilized sulfidogenic sludge characterization using electrochemical H2S microsensors

The sulfate-reduction process plays a crucial role in the biological valorization of SOx gases. However, a complete understanding of the sulfidogenic process in bioreactors is limited by the lack of technologies for characterizing the sulfate-reducing activity of immobilized biomass. In this work, we propose a flow-cell bioreactor (FCB) for characterizing sulfate-reducing biomass using H2S microsensors to monitor H2S production in real-time within a biofilm. To replace natural immobilization through extracellular polymeric substance production, sulfidogenic sludge was artificially immobilized using polymers. Physical and sulfate-reducing activity studies were performed to select a polymer-biomass matrix that maintained sulfate-reducing activity of biomass while providing strong microbial retention and mechanical strength. Several operational conditions of the sulfidogenic reactor allowed to obtain a H2S profiles under different inlet sulfate loads and, additionally, 3D mapping was assessed in order to perform a hydraulic characterization. Besides, the effects of artificial immobilization on biodiversity were investigated through the characterization of microbial communities. This study demonstrated the appropriateness of immobilized-biomass for characterization of sulfidogenic biomass in FCB using H2S electrochemical microsensors, and beneficial microbiological communities shifts as well as enrichment of sulfate-reducing bacteria have been confirmed.

Interpenetrating gelatin/alginate mixed hydrogel: The simplest method to prepare an autoclavable scaffold

The choice of sterilization method for hydrogels used for cell culture influences the ease of preparing the gel. We prepared interpenetrating gelatin/calcium alginate hydrogels containing 1% (w/v) alginate and 1-16% (w/v) gelatin by molding with the mixture of gelatin/sodium alginate solution, followed by the addition of calcium ions by incubation in calcium chloride solution. It is the simplest method to prepare autoclavable gelatin/sodium hydrogel. We measured various properties of the hydrogels including volume, Young's modulus in the compression test, storage modulus, and loss modulus in the dynamic viscoelasticity measurement. The gelatin/alginate hydrogel can be easily fabricated into any shape by this method. After autoclave treatment, the hydrogel was shrunk to smaller than the original shape in similar figures. The shape of the gelatin/alginate hydrogel can be designed into any shape with the reduction ratio of the volume. Human osteosarcoma (HOS) cells adhered to the gelatin/alginate hydrogel and then proliferated. Gelatin/calcium alginate hydrogels with a high concentration are considered to be autoclavable culture substrates because of their low deformation and gelatin elution rate after autoclaving and the high amount of cells attached to the hydrogels.

Kinetic and adsorption isotherm studies of Malachite Green dye onto surfactant-tailored alginate hydrogel beads: An influence of surfactant hydrophobicity

This study details the synthesis and characterization of surfactant-modified sodium alginate hydrogel beads crosslinked with Ba2+ ions through ionotropic gelation. Cationic surfactants such as, dodecyltrimethylammonium bromide (DTAB), didodecyldimethylammonium bromide (DDAB), and butanediyl-α,ω-bis-(dimethyldodecylammonium bromide) (GEM), were employed in the modification process. The surfactant-modified ALG-DTAB, ALG-DDAB, and ALG-GEM beads were investigated for the removal of cationic dye Malachite Green (MG) to elucidate the impact of hydrophobicity of amphiphiles on the adsorption process. The characterizations were carried out using Rheometry, Field Emission Scanning Electron Microscopy (FESEM), Infrared Spectroscopy (IR), and Energy Dispersive X-ray Spectroscopy (EDX). Under optimized conditions, ALG-GEM and ALG-DDAB demonstrated highest maximum adsorption capacity (Qmax > 700 mgg-1). The adsorption data fitted well to pseudo-second order kinetic and Langmuir adsorption models, suggesting the involvement of chemisorption phenomena with notable contributions from pore diffusion. The effects of pH, initial dye concentration, adsorbent dose, temperature, and competing ions on the removal of MG were investigated. Interestingly, ALG-GEM beads exhibited an increase in adsorption capacity with rising pH and a subsequent decrease with increasing temperature, showcasing optimal adsorption at pH 7.0 and 25 °C. The study proposes that ALG beads modified with cationic surfactants with higher hydrophobicity could offer a promising avenue in wastewater treatment processes.

Stability and biological activity enhancement of fucoxanthin through encapsulation in alginate/chitosan nanoparticles

A response surface methodology based on the Box-Behnken design was employed to develop fucoxanthin (FX) delivery nanocarrier from alginate (ALG) and chitosan (CS). The FX-loaded ALG/CS nanoparticles (FX-ALG/CS-NPs) were fabricated using oil-in-water emulsification and ionic gelation. The optimal formulation consisted of an ALG:CS mass ratio of 0.015:1, 0.71 % w/v Tween™ 80, and 5 mg/mL FX concentrations. The resulting FX-ALG/CS-NPs had a size of 227 ± 23 nm, a zeta potential of 35.3 ± 1.7 mV, and an encapsulation efficiency of 81.2 ± 2.8 %. These nanoparticles exhibited enhanced stability under simulated environmental conditions and controlled FX release in simulated gastrointestinal fluids. Furthermore, FX-ALG/CS-NPs showed increased in vitro oral bioaccessibility, gastrointestinal stability, antioxidant activity, anti-inflammatory effect, and cytotoxicity against various cancer cells. The findings suggest that ALG/CS-NPs are effective nanocarriers for the delivery of FX in nutraceuticals, functional foods, and pharmaceuticals.

Chitosan/alginate/pectin biopolymer-based Nanoemulsions for improving the shelf life of refrigerated chicken breast

This study investigated the use of nanoemulsions and various polymer coatings to enhance the quality and shelf life of chicken breast. This comprehensive study explored the antibacterial activity of essential oils (EOs) against Escherichia coli and Staphylococcus aureus, as well as the characterization of nanoemulsions (Nes) and nanoemulsion-based coatings. The antimicrobial potential of EOs, such as cinnamon, tea tree, jojoba, thyme, and black cumin seed oil, was evaluated against microorganisms, and thyme oil exhibited the highest inhibitory effect, followed by cinnamon and tea tree oil by disk diffusion analysis. The MIC and MBC values of EOs were found between 0.16-2.5 mg/mL and 0.16-5 mg/mL, respectively, while thyme EO resulted in the lowest values showing its antimicrobial potential. Then, the essential oil nanoemulsions (EONe) and their coatings, formulated with thyme oil, alginate, chitosan, and pectin, were successfully characterized. Optical microscope observations confirmed the uniform distribution of droplets in all (EONe), while particle size analysis demonstrated multimodal droplet size distributions. The EONe-chitosan coating showed the highest efficacy in reducing cooking loss, while the EONe-chitosan, EONe-alginate, and EONe-pectin coatings displayed promising outcomes in preserving color stability. Microbial analysis revealed the significant inhibitory effects of the EONe-chitosan coating against mesophilic bacteria, psychrophilic bacteria, and yeasts, leading to an extended shelf life of chicken breast. These results suggest the potential application of thyme oil and NE-based coatings in various industries for antimicrobial activity and quality preservation.

Preparation and characterization of pectin-alginate-based microbeads reinforced by nano montmorillonite filler for probiotics encapsulation: Improving viability and colonic colonization

Hydrogel microbeads can be used to enhance the stability of probiotics during gastrointestinal delivery and storage. In this study, the pectin-alginate hydrogel was enhanced by adding montmorillonite filler to produce microbeads for encapsulating Lactobacillus kefiranofaciens (LK). Results showed that the viscosity of biopolymer solutions with 1 % (PAMT1) and 3 % (PAMT3) montmorillonite addition was suitable for producing regular-shaped microbeads. A layered cross-linked network was formed on the surface of PAMT3 microbeads through electrostatic interaction between pectin-alginate and montmorillonite filler, and the surrounding LK with adsorbed montmorillonite was encapsulated inside the microbeads. PAMT3 microbeads reduced the loss of viability of LK when passing through the gastric acid environment, and facilitated the slow release of LK in the intestine and colonic colonization. The maximum decrease in viability among all filler groups was 1.21 log CFU/g after two weeks of storage, while PAMT3 freeze-drying microbeads only decreased by 0.46 log CFU/g, indicating that the gel layer synergized with the adsorbed layer to provide dual protection for probiotics. Therefore, filler-reinforced microbeads are a promising bulk encapsulation carrier with great potential for the protection and delivery of probiotics and can be developed as food additives for dairy products.

3D-printing of alginate/gelatin scaffold loading tannic acid@ZIF-8 for wound healing: In vitro and in vivo studies

In the present study, ZIF-8 metal-organic framework (MOF) modified with Tannic acid (TA@ZIF-8) was synthesized and impregnated in alginate-gelatin (Alg-Gel) hydrogel. The Alg-Gel scaffolds containing 0, 5, and 10 % of TA@ZIF-8 were fabricated through the 3D printing method specifically denoted as Alg-Gel 0 %, Alg-Gel 5 %, and Alg-Gel 10 %. XRD, FTIR, FESEM, and EDX physically and chemically characterized the synthesized ZIF-8 and TA@ZIF-8 MOFs. Besides, Alg-Gel containing TA@ZIF-8 prepared scaffolds and their biological activity were also evaluated. SEM images verified the nano-size formation of MOFs. Improved swelling and decreased degradation rates after adding TA@ZIF-8 were also reported. Increased compression strength from 0.628 to 1.63 MPa in Alg-Gel 0 % and Alg-Gel 10 %, respectively, and a 2.19 increase in elastic modulus in Alg-Gel 10 % scaffolds were exhibited. Biological activity of scaffolds, including Live-dead and Cell adhesion, antibacterial, in-vivo, and immunohistochemistry assays, demonstrated desirable fibroblast cell proliferation and adhesion, increased bacterial growth inhibition zone, accelerated wound closure and improved expression of anti-inflammatory cytokines in Alg-Gel 10 % scaffolds. The findings of this study confirm that Alg-Gel 10 % scaffolds promote full-thickness wound healing and could be considered a potential candidate for full-thickness wound treatment purposes.

Study of the degradation in an ultisol of alginate-chitosan complex and its stability and applicability as a soil conditioner

The present work describes the process of degradation of a polyelectrolytic complex (PEC) based on sodium alginate (ALG) and chitosan (CHI), buried for different time intervals, in a clayey soil (ultisol) collected from the municipality of Campos dos Goytacazes, in the northern region of the state of Rio de Janeiro, Brazil. The influence of PEC on soil moisture was also investigated. The results showed that soil moisture increased with the presence of PEC after 7 days of testing, and remained high until the end of the study. FTIR and Raman spectra showed that the breaking of the glycosidic bond (C-O-C) was responsible for the PEC degradation. Thermogravimetry results revealed that alginate was possibly degraded faster than chitosan. Microscopic analysis of the PEC revealed a fragile and fragmented surface of the samples that were buried, in comparison with those not buried. The microbiological assays of the soil confirmed the biodegradation of the polysaccharides. Chemical analysis of soil indicated that PEC did not significantly influence soil fertility. Therefore, we conclude that the PEC (ALG: CHI), formed only by electrostatic interaction, buried in clayey soil, even being biodegraded, can be a promising soil conditioner for agricultural applications.

3D-bioprinted alginate-based bioink scaffolds with β-tricalcium phosphate for bone regeneration applications

Background/purpose

3D-printed bone tissue engineering is becoming recognized as a key approach in dentistry for creating customized bone regeneration treatments fitting patients bone defects requirements. 3D bioprinting offers an innovative method to fabricate detailed 3D structures, closely emulating the native bone micro-environment and better bone regeneration. This study aimed to develop an 3D-bioprintable scaffold using a combination of alginate and β-tricalcium phosphate (β-TCP) with the Cellink® BioX printer, aiming to advance the field of tissue engineering.

Materials and methods

The physical and biological properties of the resulting 3D-printed scaffolds were evaluated at 10 %, 12 %, and 15 % alginate combined with 10 % β-TCP. The scaffolds were characterized through printability, swelling behavior, degradability, and element analysis. The biological assessment included cell viability, alkaline phosphatase (ALP) activity.

Results

10 % alginate/β-TCP 3D printed at 25 °C scaffold demonstrated the optimal condition for printability, swelling capability, and degradability of cell growth and nutrient diffusion. Addition of β-TCP particles significantly improved the 3D printed material viscosity over only alginate (P < 0.05). 10 % alginate/β-TCP enhanced MG-63 cell's proliferation (P < 0.05) and alkaline phosphatase activity (P < 0.001).

Conclusion

This study demonstrated in vitro that 10 % alginate/β-TCP bioink characteristic for fabricating 3D acellular bioprinted scaffolds was the best approach. 10 % alginate/β-TCP bioink 3D-printed scaffold exhibited superior physical properties and promoted enhanced cell viability and alkaline phosphatase activity, showing great potential for personalized bone regeneration treatments.

Alginate based biomaterials for hemostatic applications: Innovations and developments

Development of the efficient hemostatic materials is an essential requirement for the management of hemorrhage caused by the emergency situations to avert most of the casualties. Such injuries require the use of external hemostats to facilitate the immediate blood clotting. A variety of commercially available hemostats are present in the market but most of them are associated with limitations such as exothermic reactions, low biocompatibility, and painful removal. Thus, fabrication of an ideal hemostatic composition for rapid blood clot formation, biocompatibility, and antimicrobial nature presents a real challenge to the bioengineers. Benefiting from their tunable fabrication properties, alginate-based hemostats are gaining importance due to their excellent biocompatibility, with >85 % cell viability, high absorption capacity exceeding 500 %, and cost-effectiveness. Furthermore, studies have estimated that wounds treated with sodium alginate exhibited a blood loss of 0.40 ± 0.05 mL, compared to the control group with 1.15 ± 0.13 mL, indicating its inherent hemostatic activity. This serves as a solid foundation for designing future hemostatic materials. Nevertheless, various combinations have been explored to further enhance the hemostatic potential of sodium alginate. In this review, we have discussed the possible role of alginate based composite hemostats incorporated with different hemostatic agents, such as inorganic materials, polymers, biological agents, herbal agents, and synthetic drugs. This article outlines the challenges which need to be addressed before the clinical trials and give an overview of the future research directions.

Improving the thermal stability of phytase using core-shell hydrogel beads

A core-shell hydrogel bead system was designed to maintain the catalytic activity of phytase and protect its enzymatic functionality from heat treatment. The designed structure consists of a chitosan-phytase complex core and an alginate-carrageenan hydrogel shell. The core-shell hydrogel was optimized to improve phytase encapsulation efficiency and increase the thermal stability of the encapsulated phytase. After heat treatment, encapsulated phytase retained ∼ 70 % of its catalytic activity and the same secondary structure of free phytase. Fourier transform infrared spectroscopy indicated strong intermolecular interactions between chitosan and phytase in the core, but little interaction between the core and the alginate and κ-carrageenan shell, this supports the structural and functional stability of the phytase. Differential scanning calorimetry confirmed that the designed core-shell structure had a higher melting point. Encapsulating phytase in a core-shell hydrogel bead can enhance the thermal stability of phytase, which broadens the potential applications for phytase delivery.

Layer-by-layer assembly of chitosan/alginate thin films containing Salmonella enterica bacteriophages for antibacterial applications

The emergence of antibiotic resistant bacteria and the ineffectiveness of routine treatments inspired development of alternatives to biocides for antibacterial applications. Bacteriophages are natural predators of bacteria and are promising alternatives to antibiotics. This study presents fabrication of a Salmonella enterica bacteriophage containing ultra-thin multilayer film composed of chitosan and alginate and demonstrates its potential as an antibacterial coating for food packaging applications. Chitosan/alginate film was prepared through layer-by-layer (LbL) self-assembly technique. A bacteriophage, which belongs to Siphoviridae morphotype (MET P1-001_43) and infects Salmonella enterica subsp. enterica serovar Enteritidis (Salmonella Enteritidis), was post-loaded into chitosan/alginate film. The LbL growth, stability, and surface morphology of chitosan/alginate film as well as phage deposition into multilayers were analysed through ellipsometry, QCM-D and AFM techniques. The bacteriophage containing multilayers showed antibacterial activity at pH 7.0. In contrast, anti-bacterial activity was not observed at acidic conditions. We showed that wrapping a Salmonella Enteritidis contaminated chicken piece with aluminium foil whose surface was modified with phage loaded chitosan/alginate multilayers decreased the number of colonies on the chicken meat, and it was as effective as treating the meat directly with phage solution.

A biomaterial platform for T cell-specific gene delivery

Efficient T cell engineering is central to the success of CAR T cell therapy but involves multiple time-consuming manipulations, including T cell isolation, activation, and transduction. These steps add complexity and delay CAR T cell manufacturing, which takes a mean time of 4 weeks. To streamline T cell engineering, we strategically combine two critical engineering solutions - T cell-specific lentiviral vectors and macroporous scaffolds - that enable T cell activation and transduction in a simple, single step. The T cell-specific lentiviral vectors (referred to as STAT virus) target T cells through the display of an anti-CD3 antibody and the CD80 extracellular domain on their surface and provide robust T cell activation. Biocompatible macroporous scaffolds (referred to as Drydux) mediate robust transduction by providing effective interaction between naïve T cells and viral vectors. We show that when unstimulated peripheral blood mononuclear cells (PBMCs) are seeded together with STAT lentivirus on Drydux scaffolds, T cells are activated, selectively transduced, and reprogrammed in a single step. Further, we show that the Drydux platform seeded with PBMCs and STAT lentivirus generates tumor-specific functional CAR T cells. This potent combination of engineered lentivirus and biomaterial scaffold holds promise for an effective, simple, and safe avenue for in vitro and in vivo T cell engineering. STATEMENT OF SIGNIFICANCE: Manufacturing T cell therapies involves lengthy and labor-intensive steps, including T cell selection, activation, and transduction. These steps add complexity to current CAR T cell manufacturing protocols and limit widespread patient access to this revolutionary therapy. In this work, we demonstrate the combination of engineered virus and biomaterial platform that, together, enables selective T cell activation and transduction in a single step, eliminating multistep T cell engineering protocols and significantly simplifying the manufacturing process.

A Meta-analysis of PPIs Plus Alginate Versus PPIs Alone for the Treatment of GERD

OBJECTIVE

To systematically evaluate the clinical efficacy and safety of proton-pump inhibitors (PPIs) combined with alginate versus PPIs alone in the treatment of gastroesophageal reflux disease (GERD).

METHODS

Randomised Controlled Trials (RCTs) of PPIs combined with alginate and PPIs alone for the treatment of GERD in PubMed, Embase, and The Cochrane Library were searched and screened, and the risk assessment of bias and statistical analysis were performed using Rev Man 5.4 software.

RESULTS

A total of four RCTs (608 patients) were included. Before and after treatment, the change of heartburn score in the experimental group increased compared with the control group, but the difference was not statistically significant [Standard Mean Difference (SMD)= -0.29, 95%CI (-0.78, 0.19), P > 0.05]; The change of HRDQ heartburn score increased, but the difference was not statistically significant [SMD= -0.40, 95%CI (-1.04, 0.24), P > 0.05]; The number of days without heartburn during the 28-day treatment period increased, but the difference was not statistically significant [OR= 1.16, 95%CI (0.37, 3.61), P > 0.05]; The amount of reflux score increased, but the difference was not statistically significant [SMD= -0.30, 95%CI (-0.71, 0.11), P > 0.05]; The amount of change in HRDQ regurgitation score increased, but the difference was not statistically significant [SMD= -0.05，95%CI （- 1.57，0.17）， P > 0.05]； There was no statistically significant difference in adverse events with treatment [OR= 0.93, 95%CI (0.58, 1.47), P > 0.05].

CONCLUSION

In the treatment of GERD, the efficacy of PPIs combined with alginate is improved compared with PPIs alone, but there is no significant difference, and alginate does not increase the occurrence of adverse events in PPIs treatment. In the future, more subdivisions of GERD subtypes and more high-quality studies are needed to further improve the treatment strategy of GERD-related diseases.

Removal of heavy metals from wastewater by aerogel derived from date palm waste

Cellulose that has been sourced from date palm leaves as a primary component was utilised. This cellulose served as the foundational material for the development of an aerogel composite. During this process, MXene (Ti3C2Tx) played a pivotal role in enhancing the overall composition of the aerogel. To ensure the stability and durability of the resulting aerogel structure, calcium ions were introduced to the mix. These ions facilitated the cross-linking process of sodium alginate molecules, ultimately leading to the formation of calcium alginate. This cross-linking step is crucial for the enhanced mechanical and chemical stability of the aerogel. Incorporating alginate and Ti3C2Tx into the cellulose aerogel enhanced its structural integrity in aqueous conditions and increased its adsorption capacity. When evaluated with synthetic wastewater, this composite exhibited remarkable adsorption capacities of 72.9, 114.4, 92.9, and 123.9 mg/g for As, Cd, Ni, and Zn ions, respectively. A systematic study was carried out to see the effect of various parameters, including contact time, MXene concentration, pH, and temperature on the adsorption of these elements. Peak adsorption was achieved at 60 min, favoring a pH range between 6 and 8 and exhibited optimal sorption efficiency at lower temperatures. The adsorption kinetics adhered closely to a pseudo-second-order, while the Freundlich model adeptly described the adsorption isotherms. An interesting result of this research was the aerogel's regenerative potential. After undergoing a basic acid treatment, the MXene/cellulose/alginate aerogel composite could be restored and reused for up to three cycles, all while maintaining its core performance capabilities even after the rigorous cross-linking processes. In three consecutive cycles, the removal percentages for As, Cd, Ni, and Zn were 48.15%, 80.38%, 56.51%, and 86.12% in cycle 1; 37.35%, 65.63%, 45.97%, and 78.42% in cycle 2; and 28.60%, 56.22%, 34.70%, and 65.83% in cycle 3, respectively. The composite was tested in conditions resembling seawater salinity. Impressively, the aerogel continued to demonstrate a significant ability to adsorb metals, reinforcing its potential utility in real-world aquatic scenarios. These findings suggest that the composite aerogel, integrating MXene, cellulose, and alginate, is an effective medium for the targeted removal of heavy metals from aquatic environments.

Alginate and Chitosan-Based Hydrogel Enhance Antibacterial Agent Activity on Topical Application

Untreated topical infections can become chronic, posing serious health issues. Optimal skin adherence is crucial in addressing such infections. In this context, chitosan and alginate emerge as promising candidates for use as a foundation in the development of topical hydrogels. The aim of this review is to examine the literature on topical hydrogel formulations that use chitosan and alginate as foundations, specifically in the context of topical antibacterial agents. The research methodology involves a literature review by examining articles published in databases such as PubMed, Scopus, ScienceDirect, and Google Scholar. The keywords employed during the research were "Alginate", "Chitosan", "Hydrogel", and "Antibacterial". Chitosan and alginate serve as bases in topical hydrogels to deliver various active ingredients, particularly antibacterial agents, as indicated by the search results. Both have demonstrated significant antibacterial effectiveness, as evidenced by a reduction in bacterial colony counts and an increase in inhibition zones. This strongly supports the idea that chitosan and alginate could be used together to make topical hydrogels that kill bacteria that work well. In conclusion, chitosan and alginate-based hydrogels show great potential in treating bacterial infections on the skin surface. The incorporation of chitosan and alginate into hydrogel formulations aids in retaining antibacterial agents, allowing for their gradual release over an optimal period. Therefore, hydrogels specifically formulated with chitosan and alginate have the potential to serve as a solution to address challenges in the treatment of topical bacterial infections.

Isolation and quantification of alginate in choline chloride-based deep eutectic solvents

Extraction of seaweed compounds using Deep Eutectic Solvents (DES) has shown high interest. Quantification, however, is challenging due to interactions with DES components. In this research work, three chemical separation techniques were investigated to isolate and quantify alginate from a set of choline chloride-based DES. While choline chloride served as the hydrogen bond acceptor (HBA); Urea, Ethylene Glycol, Propylene Glycol, Glycerol, Sorbitol, Xylitol and Glucose were used as hydrogen bond donors (HBD). DES containing sodium alginate were subjected to precipitation with sulfuric acid 0.2 M (pH 1.6), ethanol-water mixture (80 % v/v) and calcium chloride (1 % w/v CaCl2·2H2O). Alginate in precipitates was quantified and used to evaluate the performance of each separation technique. The highest recovery yields (51.2 ± 1.3 %) were obtained using the ethanol-water mixture followed by calcium chloride (45.7 ± 1.2 %), except for polyols (e.g. sorbitol). The lowest recovery yields were obtained with acid, with a particularly low recovery yield when urea was used as HBD (9.6 ± 1.3 %). Estimations of ManA/GulA ratios showed lower values for precipitates from DES compared to the ones obtained from water. This research shows ethanolic precipitation as a suitable method for alginate separation from the studied set of choline chloride-based DES.

Catecholamines polymerization crosslinking for alginate-based burn wound dressings developed with ciprofloxacin and zinc oxide interactions

There is an increasing demand for stable and durable wound dressings to treat burn injuries and infections. Bioactive electrospun nanofibrous mats with antibacterial properties are promising for wound dressing usage. Electrospinning of biopolymers for wound dressing applications needs post-spinning crosslinking to prevent mat dissolution in moist wound environments. Here, we prepared durable wound dressing by using the Dopamine (DA) polymerization crosslinking in Alginate (ALG)/Polyvinyl alcohol (PVA) nanofibrous mats, which are developed by Ciprofloxacin (CIP) and Zinc oxide (ZO). The nanofibrous mats were investigated by FESEM, FTIR, mechanical strength, water contact angle, degradation, degree of swelling, and WVTR tests. The analyses demonstrate the nanofibrous mats with uniform and unbranched fibers, with a hydrophilic nature, which was porous, durable, and stable. Also, it showed the CIP and ZO addition enhanced their durability by crosslinking reinforcement. In addition, the drug release and antibacterial assays demonstrated the pH-sensitive release with more drug release at higher pH (bacterial invasion) and impressive antibacterial activity (up to 99 %). In the burn wound model in rats, the ALG/PVA/DA/CIP/ZO nanofibrous mats displayed excellent wound healing ability in wound closure and tissue regeneration. Also, complete re-epithelization and remodeling and highest collagen synthesis in histological assessment.

An eco-friendly versatile superabsorbent hydrogel based on sodium alginate and urea for soil improvement with a synchronous chemical loading strategy

In this paper, an eco-friendly versatile superabsorbent material was designed for soil improvement, and a synchronous chemical loading strategy was proposed. In this strategy, urea not only acted as fertilizer but also acted as a crosslinker to construct an alginate network. The microstructure, chemical structure, thermal stability and composition of the obtained SA/urea hydrogel were characterized in detail. Adsorption behavior and application performance in agriculture were evaluated. The results demonstrated that urea had two different conformations in the network. The SA/urea hydrogel had abundant pore structures with excellent water absorption performance. It could not only improve the water retention capacity of soil but also release nitrogen, phosphorus and potassium elements with degradation for as long as 9 weeks. Moreover, the hydrogel could promote plant growth, increase the nutritional composition of plants and inhibit the accumulation of harmful nitrate in plants. With advantages, including biodegradability, high water absorption, controllable degradation, excellent water retention, sustained NPK release and improved plant nutrition value, the SA/urea hydrogel has great potential for soil improvement in agriculture as an eco-friendly versatile water retention agent and can be expected to extend to more fields as a novel superabsorbent material.

Receptor mediated targeting of EGF-conjugated alginate-PAMAM nanoparticles to lung adenocarcinoma: 2D/3D in vitro and in vivo evaluation

Carboplatin (cis-diamine (1,1-cyclobutandicarboxylaso)‑platinum (II)) is a second-generation antineoplastic drug, which is widely used for chemotherapy of lung, colon, breast, cervix, testicular and digestive system cancers. Although preferred over cisplatin due to the lower incidence of nephrotoxicity and ototoxicity, efficient carboplatin delivery remains as a major challenge. In this study, carboplatin loaded alginate- poly(amidoamine) (PAMAM) hybrid nanoparticles (CAPs) with mean sizes of 192.13 ± 4.15 nm were synthesized using a microfluidic platform, then EGF was conjugated to the surface of CAPs (EGF-CAPs) for the receptor-targeted delivery. Hence, increased FITC+ cell counts were observed in A549 spheroids after EGF-CAP treatment compared to CAP in the 3D cellular uptake study. As such, the cytotoxicity of EGF-CAP was approximately 2-fold higher with an IC50 value of 35.89 ± 10.37 μg/mL compared to the CAPs in A549 spheroids. Based on in vivo experimental animal model, anti-tumor activities of the group treated with CAP decreased by 61 %, whereas the group treated with EGF-CAP completely recovered. Additionally, EGF-CAP application was shown to induce apoptotic cell death. Our study provided a new strategy for designing a hybrid nanoparticle for EGFR targeted carboplatin delivery with improved efficacy both in vitro and in vivo applications.

Selective removal of thallium from water by MnO2-doped magnetic beads: Performance and mechanism study

Aqueous thallium has posed an increasing threat to environment as human's intensified activities in mining, refining, process and discharge. Remediation on thallium pollution has been of up-most importance to water treatment. In present work, MnO2 and magnetic Fe3O4 have been implanted to sodium alginate (SA) in presence of carboxyl methyl cellulose (CMC), and the resultant beads consisted of SA/CMC/MnO2/Fe3O4 were characterized. The materials were applied to treatment of Tl-contaminated water as adsorbent in lab. The removal results revealed that the adsorption capacity reached 38.8 mg (Tl)·g (beads)-1 and almost 100 % removal efficiency was achieved. The residual Tl was below 0.1 μg·L-1, meeting the discharge standard regulated in China. The kinetic adsorption was better described as a pseudo-second-order and three-step intra-particle diffusion model. Freundlich isotherm was well fitted the experimental data. The absorbent shown an excellent competitive specificity (KTl/M: ∼104!) over common hazardous ions Cu2+, Cd2+, Co2+, Pb2+ and Cr3+, as well as naturally abundant K+ and Na+ (KTl/M: 10-102) in mimic environmental conditions. Regeneration and reusability of the absorbent was also verified by five absorption-desorpotion cycles. XPS results revealed that a redox reaction between Mn4+ with Tl+, and an ion exchange of H+ (-O-Fe) and Tl+ were assumed to be main process for the specific capturing. This study provided an efficient SA/CMC/MnO2/Fe3O4 composite beads that could be a promising adsorbent for Tl-polluted water treatment.

3D culture of alginate-hyaluronic acid hydrogel supports the stemness of human mesenchymal stem cells

The three-dimensional (3D) cell culture system is being employed more frequently to investigate cell engineering and tissue repair due to its close mimicry of in vivo microenvironments. In this study, we developed natural biomaterials, including hyaluronic acid, alginate, and gelatin, to mimic the creation of a 3D human mesenchymal stem cell (hMSC) extracellular environment and selected hydrogels with high proliferation capacity for 3D MSC culture. Human mesenchymal stem cells were encapsulated within hydrogels, and an investigation was conducted into the effects on cell viability and proliferation, stemness properties, and telomere activity compared to the 2D monolayer culture. Hydrogel characterization, cell proliferation, Live/Dead cell viability assay, gene expression, telomere relative length, and MSC stemness-related proteins by immunofluorescence staining were examined. The results showed that 3D alginate-hyaluronic acid (AL-HA) hydrogels increased cell proliferation, and the cells were grown as cellular spheroids within hydrogels and presented a high survival rate of 77.36% during the culture period of 14 days. Furthermore, the 3D alginate-hyaluronic acid (AL-HA) hydrogels increased the expression of stemness-related genes (OCT-4, NANOG, SOX2, and SIRT1), tissue growth and development genes (YAP and TAZ), and cell proliferation gene (Ki67) after culture for 14 days. Moreover, the telomere activity of the 3D MSCs was enhanced, as indicated by the upregulation of the human telomerase reverse transcriptase gene (hTERT) and the relative telomere length (T/S ratio) compared to the 2D monolayer culture. Altogether, these data suggest that the 3D alginate-hyaluronic acid (AL-HA) hydrogels could serve as a promising material for maintaining stem cell properties and might be a suitable carrier for tissue engineering proposals.

A bioinspired and sustainable route for the preparation of Ag-crosslinked alginate fibers decorated with silver nanoparticles

Functional materials obtained through green and sustainable routes are attracting particular attention due to the need to reduce the environmental impact of the chemical industry. In this work we propose a bioinspired approach for the preparation of alginate fibers containing silver nanoparticles (AgNPs), to be used for antimicrobial purposes. We demonstrate that filiform polymeric structures with length of a few meters can be easily obtained by extruding an alginate solution in an aqueous Ag+-containing bath (i.e. wet spinning) and that treating the fibers with freshly-squeezed lemon juice leads to the formation of AgNPs homogeneously distributed within the polymeric network. Using mixtures of ascorbic and citric acid to mimic lemon juice composition we highlight the influence of the aforementioned molecules on the nanoparticles formation process as well as on the properties of the fibers. Varying the amount of citric and ascorbic acid used for the treatment allows to finely tune the thermal, morphological and water absorption properties of the fibers. This evidence, along with the possibility to easily monitor the preparation through FT-IR spectroscopy, endows the fibers with a high application potential in several fields such as wound healing, water/air purification and agriculture.

Avastin-loaded 3D-printed Alginate Scaffold as an Effective Anti-Adhesive Barrier to Prevent Post-Surgical Adhesion Bands Formation

Post-operative adhesion can cause complications, such as pain, and organ blockage, in the abdominal regions. To address this issue, surgical techniques, and anti-adhesive treatments have been applied. Given the significant role of vascularization in adhesion band formation, Avastin (Ava) that targets VEGF can be applied to prevent peritoneal adhesion bands. Moreover, Alginate (Alg), a natural polysaccharide, is a promising physical barrier to prevent adhesion bands. Incorporating Ava into Alg hydrogel in a form of 3D-printed scaffold (Alg/Ava) has potential to suppress inflammation and angiogenesis, leading to reduce peritoneal adhesion bands. Following physical, morphological, and biocompatibility evaluations, the efficacy of Alg and Ava alone and their combination in Alg/Ava on the formation of post-surgical adhesions was evaluated. Upon confirming physical stability and sustained release of Ava, the Alg/Ava scaffold effectively diminished both the extent and strength of adhesion bands. Histopathological examination showed that the reduction in fibrosis and inflammation was responsible for preventing adhesion bands by the Alg/Ava scaffold. Additionally, the cytokine assessment revealed that this was due to the inhibition in the secretion of VEGF and IL-6, suppressing vascularization and inflammatory pathways. This study suggests that a 3D-printed Alg/Ava scaffold has great potential to prevent the post-surgical adhesion bands. This article is protected by copyright. All rights reserved.

Characterization of novel alginate-Aloe Vera raft systems for treatment of gastroesophageal reflux disease

Raft-forming systems are designed to relieve reflux symptoms by forming a physical barrier on top of the stomach. The present study aimed to evaluate the physico-chemical properties of alginate-aloe vera raft-forming systems for the first time. To achieve this goal, aloe vera was used in the proportion of 1 and 1.5 % in raft suspensions containing 5 % alginate as the main component of gel structure. Rafts were characterized by their volume, floating behavior, thickness, swelling properties, strength, resilience, reflux resistance, and acid neutralization capacity (ANC). Results showed the effectiveness of aloe vera in forming rafts that were voluminous, buoyant with greater total floating time (TFT), and stronger than formulations with no aloe vera. Furthermore, data showed that the presence of aloe vera could improve resilience time, swelling proportions, resistance to reflux under simulant conditions of movement in the stomach, and ANC values of rafts. Rafts were further characterized by oscillatory strain sweep test, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Evaluation of the mechanical properties of rafts displayed a viscoelastic behavior of gels corresponding to the internal cross-linked structure of rafts. This study demonstrated that designing of alginate-aloe vera rafts can be suitable for the treatment of gastro-esophageal reflux disorders.

Direct and robust citramalate production from brown macroalgae using fast-growing Vibrio sp. dhg

Brown macroalgae is a promising feedstock for biorefinery owing to its high biomass productivity and contents of carbohydrates such as alginate and mannitol. However, the limited availability of microbial platforms efficiently catabolizing the brown macroalgae sugars has restricted its utilization. In this study, the direct production of citramalate, an important industrial compound, was demonstrated from brown macroalgae by utilizing Vibrio sp. dhg, which has a remarkably efficient catabolism of alginate and mannitol. Specifically, citramalate synthase from Methanocaldococcus jannaschii was synthetically expressed, and competing pathways were removed to maximally redirect the carbon flux toward citramalate production. Notably, a resulting strain, VXHC, produced citramalate up to 9.8 g/L from a 20 g/L mixture of alginate and mannitol regardless of their ratios. Citramalate was robustly produced even when diverse brown macroalgae were provided directly. Collectively, this study showcased the high potential of brown macroalgae biorefinery using Vibrio sp. dhg.

Lactose hydrolysis in packed-and fluidized-bed reactors using a recombinant β-galactosidase immobilized on magnetic core-shell capsules

The objective of this study was to develop a bioprocess for lactose hydrolysis in diverse dairy matrices, specifically skim milk and cheese whey, utilizing column reactors employing a core-shell enzymatic system featuring β-galactosidase fused to a Cellulose Binding Domain (CBD) tag (β-galactosidase-CBD). The effectiveness of reactor configurations, including ball columns and toothed columns operating in packed and fluidized-bed modes, was evaluated for catalyzing lactose hydrolysis in both skim milk and cheese whey. In a closed system, these reactors achieved lactose hydrolysis rates of approximately 50% within 5 h under all evaluated conditions. Considering the scale of the bioprocess, the developed enzymatic system was capable of continuously hydrolyzing 9.6 L of skim milk while maintaining relative hydrolysis levels of approximately 50%. The biocatalyst, created by immobilizing β-galactosidase-CBD on magnetic core-shell capsules, exhibited exceptional operational stability, and the proposed bioprocess employing these column reactors showcases the potential for scalability.

Immobilization of α-amylase in calcium alginate-gum odina (CA-GO) beads: An easily recoverable and reusable support

A natural polysacharide, gum odina was collected from Odina wodier tree and purified. Purified gum odina was used with sodium alginate for immobilization of α-amylase. Calcium alginate-gum odina (CA-GO) beads were prepared by ionotropic gelation method to find the improvement of immobilization efficiency and reusability of α-amylase over calcium alginate (CA) beads. XRD, SEM, FTIR, beads diameter, enzyme leaching from beads, moisture content, total soluble matter and swelling study have been carried out to understand the physical morphology and mechanism of immobilization of enzyme in beads matrix. It has been observed that if the polymer ratio changes (keeping enzyme conc. & calcium Chloride conc. constant) then the size and shape of the beads will vary and at a particular range of polymer ratio, the optimal beads forms. At a certain conc.(4%w/v of SA and 1%w/v GO), the immobilization efficiency of CA-GO and CA beads were 92.71 ± 0.85 % (w/w) and 89.19 ± 0.35 %(w/w) respectively. After 8th time use, the CA-GO beads remain (~4 fold) more active than that of CA beads. The FTIR confirms that GO does not interfere with α-Amylase and alginate. Here, it can be concluded that CA-GO beads show better efficiency in respect to immobilization, reusability than CA beads only.

Alginate-CaCO3 hybrid colloidal hydrogel with tunable physicochemical properties for cell growth

Biomaterials composed of food polysaccharides are of great interest for future biomedical applications due to their great biocompatibility, tunable mechanical properties, and complex architectural designs that play a crucial role in the modulation of cell adhesion and proliferation. In this work, a facile approach was designed to obtain novel 3D alginate-CaCO3 hybrid hydrogel particles in situ. Controlling the gel concentration from 3 to 20 mg·mL-1 allows us to control the alginate-CaCO3 hydrogel particles' size and density (size variation from 1.86 to 2.34 mm and density from 1.22 to 1.29 mg/mm3). This variable also has a considerable influence on the mineralization process resulting in CaCO3 particles with varied sizes and amounts within the hydrogel beads. The measurements of Young's modulus showed that the inclusion of CaCO3 particles into the alginate hydrogel improved its mechanical properties, and Young's modulus of these hybrid hydrogel particles had a linear relationship with alginate content and hydrogel particle size. Cell experiments indicated that alginate-CaCO3 hybrid hydrogel particles can support osteoblastic cell proliferation and growth. In particular, the amount of hydroxyapatite deposition on the cell membrane significantly increased after the treatment of cells with hybrid hydrogel particles, up to 20-fold. This work offers a strategy for constructing inorganic particle-doped polysaccharide hybrid hydrogel scaffolds that provide the potential to support cell growth.

A step towards tuning the jute fiber structure and properties by employing sodium periodate oxidation and coating with alginate

This paper outlines a novel simple protocol for tuning the structure and properties of jute using sodium periodate (NaIO4) oxidation and coating with alginate. When compared to the raw jute, fabrics oxidized with a 0.2 or 0.4 % NaIO4 solution for 30-120 min exhibited an increased aldehyde group content (0.185 vs. 0.239-0.398 mmol/g), a significantly increased negative zeta potential (from -8.57 down to -20.12 mV), a slight disruption of fiber crystallinity, 15.1-37.5 % and 27.9-49.8 % lower fabric maximum force and stiffness, respectively. Owing to the removal of hydrophobic surface barrier, decreased crystallinity index and the presence of micropores on the fabrics' surfaces, oxidized fabrics have a 22.3-29.6 % improved ability for moisture sorption compared to raw fabric. Oxidized fabrics characterized by very long wetting times and excellent antioxidant activities (> 98 %), can find applications as hydrophobic packaging materials. To further extend the utilization of jute in biocarpet engineering such as water-binding geo-prebiotic supports, oxidized fabrics were coated with alginate resulting in 7.9-24.9 % higher moisture sorption and 352-660 times lower wetting times than their oxidized counterparts. This modification protocol has never been applied to lignocellulosic fibers and sheds new light on obtaining jute fabrics with tuned structure and properties intended for various applications.

3D bioprinting of multifunctional alginate dialdehyde (ADA)-gelatin (GEL) (ADA-GEL) hydrogels incorporating ferulic acid

The present work explores the 3D extrusion printing of ferulic acid (FA)-containing alginate dialdehyde (ADA)-gelatin (GEL) scaffolds with a wide spectrum of biophysical and pharmacological properties. The tailored addition of FA (≤0.2 %) increases the crosslinking between FA and GEL in the presence of calcium chloride (CaCl2) and microbial transglutaminase, as confirmed using trinitrobenzenesulfonic acid (TNBS) assay. In agreement with an increase in crosslinking density, a higher viscosity of ADA-GEL with FA incorporation was achieved, leading to better printability. Importantly, FA release, enzymatic degradation and swelling were progressively reduced with an increase in FA loading to ADA-GEL, over 28 days. Similar positive impact on antibacterial properties with S. epidermidis strains as well as antioxidant properties were recorded. Intriguingly, FA incorporated ADA-GEL supported murine pre-osteoblast proliferation with reduced osteosarcoma cell proliferation over 7 days in culture, implicating potential anticancer property. Most importantly, FA-incorporated and cell-encapsulated ADA-GEL can be extrusion printed to shape fidelity-compliant multilayer scaffolds, which also support pre-osteoblast cells over 7 days in culture. Taken together, the present study has confirmed the significant potential of 3D bioprinting of ADA-GEL-FA ink to obtain structurally stable scaffolds with a broad spectrum of biophysical and therapeutically significant properties, for bone tissue engineering applications.

Influence of biopolymer composition and crosslinking agent concentration on the micro- and nanomechanical properties of hydrogel-based filaments

Hydrogel filaments were manufactured using wet spinning technique, incorporating variations in the concentrations of sodium alginate, gelatin, and calcium chloride (crosslinking agent). The combination of biopolymer concentrations was determined using design of experiments (DoE) approach. The resulting filaments were produced from the developed hydrogels. Tensile and vertical strength analyses of the filaments were conducted using an electromechanical extensor. Atomic force microscopy was employed to evaluate the roughness, viscoelasticity, retraction, and deflection of the hydrogels. By employing DoE, a total of seventeen different combinations of biopolymers and crosslinkers were generated to construct the hydrogels. The filaments exhibited variations in electromechanical traction (measured in kPa) and produced distinct stress peaks. Furthermore, diverse roughness values were observed among the tested materials, with the combinations featuring higher concentrations of sodium alginate displaying the highest Young's modulus. This study demonstrates that manipulating the concentrations of biopolymers and crosslinking agents can modulate the micro and nanomechanical properties of biopolymeric filaments.

Multifunctional alginate/polydeoxyribonucleotide hydrogels for promoting diabetic wound healing

A multifunctional alginate/PDRN hydrogel system by ionic crosslinking and the Schiff base reaction between oxidized alginate (OA) and PDRN was developed in the present study. Biocompatibility assessment of the PDRN-loaded OA hydrogels showed a significant enhancement in cell viability in human dermal fibroblast (HDF) cells. In addition, hydrogels showed migratory, anti-inflammatory, intracellular reactive oxygen species scavenging, and anti-apoptotic activities. In vivo studies using a streptozotocin-induced diabetic Wister rat model indicated that OA-4PDRN had the highest percentage of wound closure (96.1 ± 2.6 %) at day 14 compared to the control (79.0 ± 2.3 %) group. This was accompanied by up-regulation of vascular endothelial growth factor (VEGF), interleukin-10 (IL-10), and transforming growth factor-beta (TGF-β) accompanied by down-regulation of pro-inflammatory markers (IL-6, IL-1β). Following histopathological observations, PDRN-loaded OA hydrogel ensured tissue safety and induced wound healing with granular tissue formation, collagen deposition, re-epithelialization, and regeneration of blood vessels and hair follicles. The downregulation of inflammatory cytokines (CD68) and expression of angiogenesis-related cytokines (CD31) in wound sites revealed the suppression of inflammation and increased angiogenesis, ensuring skin tissue regeneration in diabetic wound healing. In conclusion, the findings suggest that PDRN-loaded OA hydrogel has enormous therapeutic potential as a diabetic wound dressing.

Biopolymer-metal composites for selective removal and recovery of waterborne orthophosphate

Orthophosphate (Pi) remediation from effluent serves to address global water security by preventing eutrophication. Herein, chitosan (C), alginate (Alg) and three respective metal systems (Fe3+, Al3+, Cu2+) were used to prepare binary (BMC) or ternary (TMC) metal composite adsorbents. Their physicochemical properties were analyzed through XPS, IR and TGA, while the adsorption properties of the composites were characterized via adsorption isotherms and single-point experiments in saline environmental water. Al-composites formed Al-O complexes, while Fe- and Cu-composites formed in the presence of the biopolymer backbone FeO(OH) and Cu2(OH)3NO3, respectively. While Al-composites showed the highest bound water fraction (up to 16%), the Cu-composites (Cu-TMC-N, CuC-BMC-N; where N = nitrate) revealed the lowest water content. Alginate-based binary composites showed slightly higher water content, as compared to ternary and binary chitosan composites. Among the four materials (Al-TMC-N, Fe-TMC-N, Cu-TMC-N and CuC-BMC-N), the Al-TMC showed the highest Pi selectivity over sulfate, along with high Pi removal-% even in a binary mixture (sulfate + orthophosphate) despite the presence of competitive anion species. Upon spiking saline groundwater samples with low Pi (5 mg/L) that contains 2060 or 6030 mg/g sulfate, Al-TMC-N showed the highest Pi selectivity, followed by Fe-TMC-N. This trend in adsorption of Pi among the various composites is understood based on the HSAB principle for the conditions employed in this study. Removal efficiencies of Pi above 60% in Well 1 (ca. 2000 mg/L sulfate) and above 30% in Well 3 (ca. 6030 mg/L sulfate). Herein, environmentally compatible and sustainable composite adsorbents were prepared that reveal selective Pi recovery from (highly) saline groundwater that can mitigate eutrophication in aqueous media.