Alginate Research Articles

Competitive effects of anion mobility and viscous forces on the interactions of hyaluronic acid and alginic acid with hofmeister salts

The specific ion effect takes into account the hydration, mobility, and kosmotropic/chaotropic effects. However, another important aspect to consider is the solution viscosity, which influences ion mobility. A limited number of publications have considered the impact of specific ion effects on polyelectrolytes. However, none of the studies have considered the viscous effect of polyelectrolytes. This study aims to investigate the impact of kosmotropic and chaotropic anions on negatively charged alginic acid and hyaluronic acid using dynamic light scattering, rheology, and molecular dynamic simulations. Different concentration regimes and the change in the chain conformations in these regimes, along with the viscosity scaling and impact of the salts on the polyelectrolytes, have been discussed. An interesting finding regarding the solution viscosity was reported. The solution viscosity leads to the reversal of the diffusivity and viscosity trend of the polymer with kosmotropes and chaotropes. A threshold is also identified above which viscous forces dominate. Specific ion effects dominate below the threshold. It was concluded that the specific ion effect shows a competitive nature with the viscous forces in the case of a high-viscosity polyelectrolyte solution, which becomes an important aspect to consider for unveiling such interactions. Prior knowledge of the conformations of polymers can be used for designing drug delivery/nutrient delivery systems and for understanding phase separation behavior. Considering the viscosity of polymer solution becomes an important factor which, in turn, impacts the anion's mobility and ultimately influences the polymer conformations.

Micromixer driven by bubble-induced acoustic microstreaming for multi-ink 3D bioprinting.

Recently, the 3D printing of cell-laden hydrogel structures, known as bioprinting, has received increasing attention owing to advances in tissue engineering and drug screening. However, a micromixing technology that efficiently mixes viscous bioinks under mild conditions is needed. Therefore, this study presents a novel method for achieving homogeneous mixing of multiple inks in 3D bioprinting through acoustic stimulation. This technique involves generating an acoustic microstream through bubble oscillations inside a 3D bioprinting nozzle. We determined the optimal hole design for trapping a bubble, hole arrangement, and voltage for efficient mixing, resulting in a four-fold increase in mixing efficiency compared to a single bubble arrangement. Subsequently, we propose a nozzle design for efficient mixing during bioprinting. The proposed nozzle design enabled the successful printing of line structures with a uniform mixture of different viscous bioinks, achieving a mixing efficiency of over 80% for mixing 0.5-1.0 wt% sodium alginate aqueous solutions. Additionally, acoustic stimulation had no adverse effects on cell viability, maintaining a high cell viability of 88% after extrusion. This study presents the first use of a bubble micromixer in 3D bioprinting, demonstrating gentle yet effective multi-ink mixing. We believe this approach will broaden 3D printing applications, particularly for constructing functional structures in 3D bioprinting.

Enhancing eco-friendly coatings: Aqueous olive leaves extract fortifies macroalgae-based packaging materials

This study incorporated bioactive compounds extracted from olive leaves (Olea europaea L.) into biodegradable films designed for preserving perishable food items like fruits and vegetables. Olive leaves, sourced from Lesvos island in Greece, yielded three aqueous extracts - OL1, OL2, and OL3 – representing different cultivated species. The antioxidant potential and phenolic compound profile of these extracts were analyzed. Subsequently, these extracts were integrated into 2% sodium alginate solutions, and the resulting mixtures were cast into 90 mm Petri dishes to form solid biofilms. Our findings reveal that the olive leaf extracts offer protection against UV–VIS radiation. Particularly, OL1 showcased the highest antioxidant capacity among the extracts examined. For the solid biofilms, various physical characteristics such as weight, diameter, density, and thickness were measured, alongside evaluating humidity, solubility in water, and water vapor permeability. The rheological properties of these solutions, influenced by temperature and extract addition, affect the viscosity, flow behavior, and gelation capacity, crucial for coating applications. Our research not only explores the impact of olive leaf extracts and glycerol as a plasticizer on biofilm solutions but also sheds light on increased opacity, reduced light absorption, and altered rheological properties. This endeavor aligns with the ongoing pursuit of sustainable packaging alternatives, emphasizing the crucial role of bioactive compounds in enhancing the functionality and eco-friendliness of biodegradable films.

Sodium alginate- and chitosan-based hydrogels with different network charges for selective removal of cationic and anionic dyes from water

ABSTRACT The grafting of chitosan (CH) and sodium alginate (SA) biopolymers with glycidyl methacrylate (GMA) and acrylamide (AAm) monomers, combined with graphene oxide (GO), led to the formation of bio-based hydrogels. These hydrogels, named CH -GO -hydrogel (GO/CH-g-poly (AAm-co-GMA)), CH -GO -hydrogel (CH-g-poly (AAm-co-GMA)), SA -GO -hydrogel (GO/SA-g-poly(AAm-co-GMA)), and SA -hydrogel (SA-g-poly(AAm-co-GMA)), were tested as selective dye adsorbents. While the chitosan-based hydrogels exhibited positive zeta potential values ranging from +27.5 to +0.1 mV, alginate-based samples had negative values between −10.4 to −41.7 mV in pH conditions from 3.0 to 9.0. Adding GO nano-fillers reduced the swelling capacity of both hydrogels, with water absorption (WA) values for SA -GO -hydrogel and SA -hydrogel recorded at 10.1 and 22.2 g/g, respectively. The ability of these materials to adsorb dyes, specifically crystal violet (cationic) and Congo red (anionic), was confirmed. Factors such as adsorbent dosage, initial pH, dye concentration, shaking time, and temperature were analyzed to determine dye adsorption capacity. Interestingly, the pristine hydrogels, free of GO, performed better than their nanocomposite counterparts. Adsorption capacities (qm) for crystal violet and Congo red with SA -hydrogel, SA -GO -hydrogel, CH -hydrogel, and CH -GO -hydrogel was 909.1, 714.3, 454.5, and 400.0 mg/g, respectively.

Essential oil release from zein particles as modulated by inorganic coating and biopolymeric networking

Zein particles (ZPs) have emerged as a popular delivery carrier for hydrophobic bioactive substances. However, some lipophilic compounds are easily released from ZPs because of the low polarity compatibility between zein and the compounds. The loss of encapsulated substances is particularly evident for citrus essential oil (CEO), an extremely hydrophobic ingredient. The premature release of CEO from ZPs was mitigated by developing a modification approach using ZPs coated with calcium phosphate (CaP) and networked with Ca2+-alginate gel (CaAlg). The approach involved the preparation of ZPs (through the antisolvent addition procedure) in phosphate buffer, and supplementation of the particles consecutively with sodium alginate and Ca2+ ions (as CaCl2). This procedure resulted in retention of up to 28% of CEO within ZPs after the accelerated storage experiment. Under in vitro gastric and intestinal digestion condition, the CaP-coated and CaAlg-networked ZPs had a significantly lower release of CEO compared to their non-coated and non-networked counterparts. The morphology of the particles was investigated by scanning (SEM) and transmission (TEM) electron microscopies, as well as confocal laser scanning microscopy. SEM imaging showed that sodium alginate could facilitate the formation of CaP coating through preventing CaP crystallization. CaP coating also decreased the ZPs fusion/aggregation as evidenced by comparing the ζ-potential and microscopic morphology of the particles. Examination of the infrared spectra of the particles revealed that the formation of CaP coating occurred at Ca2+ ion concentrations ≥ 10 mM.

Melting rheology of Prandtl Eyring hybrid nanofluid flow with slip condition past a Riga Wedge through Darcy-Forchheimer medium

The current matter examines the 2D flow of Prandtl Eyring hybrid (Al2O3+Cu/SA) nanoliquid through a porous media with a velocity slip mechanism along the melted Riga wedge. A combination of Alumina (Al2O3) and Copper (Cu) nanoparticles in a sodium alginate (SA) base liquid is called a hybrid nanofluid. Furthermore, the physical meaning of the flow behavior is explored with Darcy-Forchheimer. Heat sink/source, nonlinear thermal energy, and viscous dissipation, applications all need the computation of heat transference. The current flow problem is modelled in the system of highly nonlinear PDEs based on flow assumptions. We use an appropriate similarity transformation to turn these PDEs into ODEs. We simulate the obtained paired nonlinear higher-order ODEs employing the ideas from the bvp4c Matlab scheme. With the help of the graphics, several physical dimensionless factors are discussed and their unique effects on the flow profile are shown. One of the study's most notable findings is that applying boundary slip and Riga impact can increase velocity because of weak electromagnetic forces. At lower velocities, wedge flow through a Darcy-Forchheimer medium is primarily driven by viscous resistance under Darcy's law, with little in the way of inertial forces. It is also noteworthy that the temperature differential, thermal radiation, nanoparticle volume percentage, and Eckert number all enhance the nanoliquid thermal profile in both Prandtl Eyring fluid and hybrid nanofluid. The Nusselt number is increased for both the melting and fluid parameters.

Poly(acrylic acid)-Sodium Alginate Superabsorbent Hydrogels Synthesized by Electron-Beam Irradiation-Part II: Swelling Kinetics and Absorption Behavior in Various Swelling Media.

Hybrid hydrogels with superabsorbent properties based on acrylic acid (20%), sodium alginate (0.5%) and poly(ethylene oxide) (0.1%) were obtained by electron-beam irradiation between 5 and 20 kGy, and are characterized by different physical and chemical methods; the first results reported showed gel fractions over 87%, cross-link densities under 9.9 × 103 mol/cm3 and swelling degrees of 400 g/g. Two types of hydrogels (without and with 0.1% initiator potassium persulfate) have been subjected to swelling and deswelling experiments in different swelling media with different pHs, chosen in accordance with the purpose for which these superabsorbent materials were obtained, i.e., water and nutrients carriers for agricultural purposes: 6.05 (distilled water), 7.66 (tap water), 5.40 (synthetic nutrient solution) and 7.45 (organic nutrient solution). Swelling kinetics and swelling dynamics have been also studied in order to investigate the influence of swelling media type and pH on the absorption phenomenon. The swelling and deswelling behaviors were influenced by the hydrogel characteristics and pH of the swelling media. Both the polymeric chain relaxation (non-Fickian diffusion) and macromolecular relaxation (super case II) phenomenon were highlighted as a function of swelling media type.

Encapsulation of Mentha aquatica methanol extract in alginate hydrogel promotes wound healing in a murine model of Pseudomonas aeruginosa burn infection

Burn injuries are the fourth most prevalent devastating form of trauma worldwide. Among the most extensively explored materials, composite dressings with alginate loaded with herbal extract can be mentioned. This research aimed to develop a sodium alginate (SA)-based hydrogel encapsulated with Mentha aquatica (MA) methanol extract and investigate its therapeutic efficacy in the infected burn mouse model. SEM, FTIR, in vitro extract release, HPLC, mechanical test, contact angle, swelling, degradability, and temperature response properties were used to analyze the hydrogel scaffold's physicochemical structure. Additionally, the antibacterial activity and MIC level of the extract, cell cytotoxicity, and macroscopic and microscopic analysis of the wound healing process were done using Masson's trichrome and hematoxylin-eosin staining. The physicochemical properties of the SA hydrogel encapsulated with MA extract were verified. The lowest inhibitory dose of the extract was determined to be 12.5 mg/ml. Application of SA/MA hydrogel to localized wounds of deep third-degree burns demonstrated faster tissue regeneration, collagen recovery, and eradication of bacterial infection. This research focused on the design and the preparation of a novel and effective biomaterials-based medical product, which has the potential to rehabilitate infected and injured skin tissue; therefore, it can be a promising candidate for wound dressing applications.

Hydrogel and Microgel Collaboration for Spatiotemporal Delivery of Biofactors to Awaken Nucleus Pulposus‐Derived Stem Cells for Endogenous Repair of Disc

AbstractDepletion of nucleus pulposus‐derived stem cells (NPSCs) is a major contributing factor to the attenuation of endogenous regenerative capacity in intervertebral disc degeneration (IVDD). Introducing a hydrogel drug delivery system is a potential strategy for counteracting endogenous cell depletion. The present study proposes a delivery platform for the spatiotemporal release of multiple drugs by combining sodium alginate hydrogels with gelatin microgels (SCGP hydrogels). The SCGP hydrogels facilitated the initial release of chondroitin sulfate (ChS) and the gradual release of an independently developed parathyroid hormone‐related peptide (P2). The combined action of these two small molecule drugs “awakened” the reserve NPSCs, mitigated cell damage induced by H2O2, significantly enhanced their biological activity, and promoted their differentiation toward nucleus pulposus cells. The mechanical and viscoelastic properties of the hydrogel are enhanced by physical and chemical dual cross‐linking to adapt to the loading environment of the degenerated disc. A rat IVDD model is used to validate that the SCGP hydrogel can significantly inhibit the progression of IVDD and stimulate the endogenous repair of IVDD. Therefore, the spatiotemporal differential drug delivery system of the SCGP hydrogel holds promise as a convenient and efficacious therapeutic strategy for minimally invasive IVDD treatment.

Optimizing alginate extraction using Box-Behnken design: Improving yield and antioxidant properties through ultrasound-assisted citric acid extraction

The Box-Behnken Design was employed to optimize the extraction of alginate (ALG) from Sargassum cymosum C. Agardh using ultrasound-assisted treatment and substituting hydrochloric acid with citric acid during the acidic step. The study aimed to maximize yield and enhance the functional properties of the polysaccharide. The effects of pH of the citric acid (CA) solution, ultrasound power, and treatment time were evaluated in terms of yield, viscosity-average molecular weight (Mw), dynamic viscosity (µdyn), and antioxidant capacity (AC) of the ALG. The optimized conditions (176 W, 15 min, pH 1) resulted in a yield of 54.20 %, Mw of 202.56 kDa, µdyn of 10.43 mPa•s, and AC of 80.81 µM Trolox g-1. The lowest pH was found to be optimal for enhancing alginate extraction efficiency and improving its properties (viscosity and antioxidant capacity). Under optimized conditions, the CA solution resulted in a higher ALG yield with minimal changes in Mw and µdyn, while also retaining the main functional groups and chemical bonds, and doubling the AC compared to hydrochloric acid. The results indicate that ultrasound-assisted extraction is a promising method for extracting alginate from brown algae and that CA can satisfactorily replace the conventional solvent used in the acidic treatment.

Formulation and evaluation of medicated lozenges containing the solid dispersion of Clotrimazole /PEG 6000 for the treatment of oral candidiasis

The study aimed to formulate Clotrimazole (CLM) as solid dispersion medicated lozenges with enhanced dissolution for treating oropharyngeal candidiasis. They are suitable for many patients and easy to administer. The study used the solvent evaporation method to prepare solid dispersions of CLM using polyethylene glycol 6000 and polyvinyl pyrrolidone at different drug-to-carrier weight ratios. The study found that PEG 6000, when used at a 1:1 weight ratio, significantly improved the dissolution of CLM. The results of the FTIR studies showed that the drug was dispersed within PEG 6000, and there was no drug interaction with the excipients used in medicated lozenge formulations. A 32-factorial design was used to develop, optimize, and evaluate nine formulations of the solid dispersion of CLM/PEG 6000 medicated lozenges for improved therapeutic outcomes. We fabricated the lozenges using biocompatible polymeric gelling agents (chitosan, methyl cellulose, and sodium alginate) at three different levels (0.5, 1, and 1.5%). All the medicated lozenges were uniform in weight and drug content within USP limits, with complete drug release rates ranging from 10–20 minutes for chitosan and sodium alginate formulations, compared to 60 minutes for methyl cellulose. The results showed that the type of polymer and its concentration significantly impacted drug release. The optimized formulation, F-3, containing 1.5% CH, exhibited a drug release of 100.83% ±0.68 at the end of 10 minutes. It demonstrated significant antifungal activity against Candida albicans (p < 0.05), making it suitable for drug delivery in the oral cavity.

Valence fixable ferrozine gel rod combined with smartphone for facile determination of redox-active Fe2+ in environmental water

Ferrous ion (Fe2+) can indicate the redox situation of water and also plays an important role in maintaining the ecological balance of water bodies. However, due to the redox-active property of Fe2+, it is still a huge challenge to sensitively and accurately determine Fe2+ especially in interstitial water. Herein, we prepared a ferrozine gel rod for valence fixation during sampling and subsequent smartphone-based detection of Fe2+. The electrode potential of the redox pair can be varied through the formation of Fe2+-ligand complexes, and when Ecomplex was higher than EO2/OH−, the oxidation of Fe2+ by O2 was hindered, thus achieving the valence fixation of Fe2+. Six ligands were screened, and it was found that ferrozine could effectively increase the redox potential after complexing with Fe2+, and also exhibits an obvious color change while fixing the valence of Fe2+. To facilitate Fe2+ detection, a cross-linked porous polymer gel rod prepared by acrylamide and sodium alginate was used to encapsulate the ferrozine molecules. The ferrozine gel rod enabled fixation the valence of Fe2+ longer than 30 days, and the resulted purple-red color was pictured and analyzed by a smartphone. Ultimately, the developed ferrozine gel rod sensing system was able to achieve sensitive and linear detection of Fe2+ in the range of 1–200 μM with the limit of detection as low as 0.33 μM, and it also exhibited excellent selectivity and anti-interference ability. The accuracy and reliability of the method was verified by the determination of Fe2+ in spiked water samples and certified standard reference water samples. Finally, the ferrozine gel rod sensing system was successfully applied to in-situ detection of Fe2+ in interstitial water, overlying water and upper water of lake and river. This facile system that enabled valence fixation and fast detection is promising for detection of Fe2+ in environmental waters.

Conductive, sensitivity, flexibility, anti-freezing and anti-drying silica/carbon nanotubes/sodium ions modified sodium alginate hydrogels for wearable strain sensing applications

The biocompatibility and salient gelling feature of alginate via forming the interpenetrating network structure has received extensive interests for different applications. Traditional alginate hydrogels freeze at low temperature and evaporate easily at room temperature, leading to reduced performance. Consequently, it is crucial to develop methods to prevent alginate hydrogel from freezing at subzero temperature and dehydration at normal temperature to maintain the performance stability. Utilizing polyacrylic acid, sodium alginate, and acrylamide-hydroxyethyl methacrylate copolymers as flexible matrix materials, this study develops a wearable silica (SiO2)/carbon nanotubes (CNT)/sodium ions (SiO2/CNT/Na+) modified sodium alginate hydrogel strain sensor characterized by high sensitivity, flexibility, and anti-freezing and anti-drying properties. The hydrogel doped with NaCl (50 mg), CNT (10 mg) and M-SiO2 (200 mg) shows excellent mechanical and electrical properties, the tensile strength is 436 KPa, the break elongation is 426 %, the elastic modulus is 99 KPa, and the toughness is 897 kJ/m3. The modified sodium alginate hydrogel used as strain sensor shows fast response time (∼100 ms), high sensitivity factor and excellent stability. The strain sensor exhibits excellent flexibility, ductility, self-adhesion, anti-freezing and anti-drying properties, significantly enhancing its strain sensing application field.

Thermal responsive sodium alginate/polyacrylamide/poly (N-isopropylacrylamide) ionic hydrogel composite via seeding calcium carbonate microparticles for the engineering of ultrasensitive wearable sensors

The design of polyelectrolyte hydrogel with unique tensile and adhesive properties which can be applied across disciplines has gradually become a popular trend. However, the phenomenon of global warming and the emergence of extreme weather, it still faces some urgent problems that should be solved, such as the optimal utilization of polyelectrolyte hydrogel across a wide range of temperatures. Herein, a wide temperature sensitivity and conductivity hydrogel based on sodium alginate, acrylamide and N-isopropylacrylamide was constructed, which exhibited excellent adhesion and temperature conductivity. It is worth noting that after the inclusion of CaCO3 and NaCl in the hydrogel, the hydrogel showed excellent tensile properties (fracture strain >2000 %). Within a wide temperature range (−15–50 °C), it exhibits exceptional electrical conductivity (2.75 S ∗ m−1) and sensitivity (GF = 8.76 under high strain). This innovative intelligent polyelectrolyte hydrogel provides suitable strategy for flexible sensors, smart wearable devices and medical monitoring equipment.

Fabrication and characterization of bioactive curdlan and sodium alginate films for enhancing the shelf life of Volvariella volvacea

This study aimed to develop bioactive films based on curdlan (CD) and sodium alginate (SA) to enhance the shelf life of the Volvariella volvacea mushroom. A stable nanoemulsion of droplet size of 150.1 ± 5 nm was first formulated using 5% soy protein (Sp) and 10% lavender essential oil (LEO), achieved by ultrasound treatment for 10 min, resulting in small droplet sizes. In parallel, a CD-SA film was prepared by mixing them in a 1:1 ratio. The SpLEO nanoemulsion was then ex situ added to the CD-SA film at varying concentrations (4%, 6%, 8%, and 10%). The resulting bioactive film exhibited desirable properties, including water vapor permeability (1.15 ± 0.05 × 10−10 g m−1 Pa−1 s−1), swelling rate (547%), and tensile strength (10.1 ± 1.3 MPa). Docking and structural analyses suggested that ultrasound treatment enhanced the intermolecular hydrogen bonding, creating a uniform and regular surface and reduced crystallinity. The CD-SA film with ultrasound-treated 8% SpLEO nanoemulsion [i.e., (CD-SA/SpLEO-8)US] showed antibacterial activity against Escherichia coli and Staphylococcus aureus and extended the freshness of straw mushrooms prevention of spoilage during storage. Additionally, the film reduced respiration rate (975 mg CO₂/kg/h at 96 h) and ethylene production (160 ng/kg/s by 96 h) while effectively inhibiting straw mushroom autolysis. This led to a reduction in browning (2.91), total soluble solids (7.5%), weight loss (13.9%), and polyphenol oxidase activity (0.08 ΔOD420/min⋅g), thereby extending the shelf life of the mushrooms to 96 h. These findings highlight the potential of incorporating different molecules using ultrasound treatment to develop innovative edible films for food preservation.

Biodecolorization of Azo Dye by Bacteria Alcaligenes faecalis Sub Sp. Phenolicus Isolated from a Bark-Beetle Tunnel Developed in Peltophorum Pterocarpum Plant

This study assessed the decolorization of reactive red 120 (RR120) by Alcaligenes faecalis subsp. phenolicus strain isolated from the bark borer insect (Indarbela tetraonis) tunnel developed in Peltophorum pterocarpum. The optimal parameters for the dye of decolorization 0.1 mg/L of dye were pH 7, temperature 35°C, fructose (0.4% w/v) as the carbon supply (0.4% w/v), peptone (0.2% w/v) as the nitrogen source (0.4% w/v), 12 hours of static conditions, and 0.3 ml of inoculums. Cell suspension, sodium alginate (3%, w/v), and PVA (5%, w/v) immobilized cell beads (10 beads 0.5 mm in size) were used in the batch continuous reactor for complete bio-decolorization of RR120. The batch reactor was subjected to 5 cycles of batches for 3 days of constant use. Under optimal conditions, the batch mode achieved more than 99% dye decolorization and fabric color removal in less than 48 hours of contact. When the control and dye-decolorized media were analyzed using UV spectroscopy, the absorbance of the control medium was higher than that of the decolorized media. GC-MS and FTIR analysis revealed the basic compounds and functional groups of the parent RR120 dye. This strain decolored 76.51% of AB 113, 96.8% of orange II, 98.47% of congo red, 98.3% of RR120, 97.92% of phenol red individual dyes, and 94.72% of the dye mixture at 12 hours. A. faecalis subsp. Phenolicus strains produced positive results in the qualitative analytical test of exopolysaccharides (EPS) and plant growth-promoting rhizobacteria (PGPR) production. The RR120 was decolorized in the presence of heavy metal ions by A. faecalis sub-sp. Phenolicus bacteria.

Investigating the electronic properties of edge glycine/biopolymer/graphene quantum dots

This study systematically investigated four types of graphene quantum dots (GQDs) AHEX, ZTRI, ZHEX, and ATRI, and their interactions with glycine to form GQD-glycine complexes. Utilizing density functional theory (DFT) and the PM6 semiempirical method, the study analyzed electronic properties and structure-activity relationships. Global reactivity indices were calculated using Koopmans’ theorem, and quantitative structure-activity relationship (QSAR) parameters were assessed via SCIGRESS 0.3. The study further explored interactions using density of states (DOS) and quantum theory of atoms in molecules (QTAIM) analyses. Key findings revealed that glycine interaction significantly increased the total dipole moment (TDM) and decreased the HOMO/LUMO energy gap (ΔE) for the GQD-glycine complexes. Notably, ZTRI/glycine showed a TDM of 4.535 Debye and a reduced ΔE of 0.323 eV, indicating enhanced reactivity. Further interactions with cellulose, chitosan, and sodium alginate identified the ZTRI/glycine/sodium alginate composite as the most reactive, with a TDM of 8.020 Debye and the lowest ΔE of 0.200 eV. This composite also exhibited the highest electrophilicity index (56.421) and lowest chemical hardness (0.145 eV), underscoring its superior reactivity and stability. DOS analysis revealed that biomolecules contributed the most to molecular orbitals, with carbon atoms contributing the least. QTAIM analysis confirmed the greater stability of the ZTRI/glycine/sodium alginate complex compared to other studied composites. These results highlight the enhanced reactivity and stability of GQDs when interacting with glycine and sodium alginate.

ALGINATE-BASED CELL ENCAPSULATION USING DIFFERENT CROSSLINKER ELEMENTS

Alginate microcapsules are the most frequently used materials for cell transplantation. Different crosslinkers affect crosslinking affinity, which has a significant influence on microcapsule properties. The objective was to prepare in vitro microcapsules using calcium, barium, iron, manganese, nickel, and strontium as divalent cations to observe their potential for use in cell transplantation. Sodium alginate was added dropwise to the individually prepared crosslinkers to observe diffusion-based gelling. Alginate microcapsules were investigated regarding capsule stability, physiological properties, and cell viability. After 30 days of incubation, cell viability was greater than 90% for the cell-encapsulated microcapsules when crosslinked with CaCl2 and NiCl2. Viability decreased in the following order: [Formula: see text]. A compression test was performed to investigate the required force to deform 30% of microcapsules, and only MnCl2, FeCl2 (180[Formula: see text]mM), and NiCl2 (50[Formula: see text]mM) demonstrated higher resistance to the applied force than CaCl2. Except for the FeCl2 group, all cell-encapsulated microcapsules remained intact for 45 days. Potential sensitivities to CaCl2 during cell transplantation may compel alternative crosslinker usage, and our study revealed that NiCl2 and BaCl2 can be used as alternative crosslinkers to CaCl2 due to their high cell viability and consistent stability.

Simultaneously enhancing strength and toughness of coir fiber through NaOH and sodium alginate treatment

Coir fibers are commonly subjected to alkali treatment to eliminate impurities and tune their mechanical properties. However, this process can damage the fibers’ microstructures, posing a challenge in significantly enhancing both strength and toughness simultaneously. Herein, we successfully enhanced both strength and toughness of coir fibers through a combined treatment with NaOH and sodium alginate aqueous solution. Coir fibers treated with 5 wt% NaOH solution, followed by 0.5 wt% sodium alginate solution, exhibit a tensile modulus of 2475.0 MPa, a tensile strength of 126.4 MPa, and a toughness of 30.7 MJ/m³, representing improvements of 57.1 %, 72.7 %, and 116.2 %, respectively, compared to the raw fibers. Mechanistic studies revealed that NaOH treatment effectively removes pectin, hemicellulose and lignin from coir fibers but introduces numerous defects. Sodium alginate can repair these defects by forming hydrogen bonds with the rich oxygen-containing group of coir fibers. The combined treatment also increases the crystallinity of coir fibers from 30.3 % for the raw fibers to 44.1 % by removing a large number of amorphous substances. Additionally, the combined treatment reduces the microfibril angle from ∼63.6° to ∼46.6° by elongating the helix structure and filling the gaps between helical fibers. Our cost-effective strategy not only promotes the applications of coir fibers but also provides guidance for the modification of other natural plant fibers.

Radiation protection of sodium alginate and its regulatory effect on intestinal microflora in mice

Prolonged or high-dose exposure to ionizing radiation (IR) can cause damage to normal tissues of the body. Therefore, it is imperative to find effective radiation protective agents to mitigate IR-induced damage. This study evaluated the effects of sodium alginate (SA) on the radiation protection and modulatory effects of gut microorganisms using a 60Coγ-induced damage model in mice. Results showed that SA could reduce the damage of hematopoietic system; and alleviate the oxidative damage in irradiated mice by inhibiting the content of malondialdehyde (MDA) and increasing the activities of superoxide dismutase (SOD) and glutathione (GSH) in serum, spleen, jejunum and liver. Moreover, SA treatment ameliorated IR-induced small intestine lesions and alleviated liver injury. This was consistent with decreased levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and tumor necrosis factor-α (TNF-α), and increased levels of interferon-γ (IFN-γ) and interleukin-2 (IL-2) after SA treatment. Furthermore, SA treatment reversed IR-induced gut dysbiosis, elevated the Firmicutes/Bacteroidetes ratio, increased the beneficial bacteria and reduced the pathogenic bacteria in the small intestine. In conclusion, the present study demonstrated that SA exerted good radioprotective effect by improving hematopoietic system, alleviating oxidative stress, attenuating liver injury and inflammatory response, and modulating the intestinal microbiota in irradiated mice.