Crosslinked Sodium Alginate Research Articles

Improving flexible actuating behaviors of gel-based artificial muscles through chamomile polysaccharide crosslinking

Abstract The flexible actuating behaviors of gel-based artificial muscles (GBAMs) are contingent upon the properties of their hydrogel actuating membranes. While the current preparation system for these membranes is deemed flawless, the electromechanical characteristics are constrained by the inherent properties of the material. The majority of raw materials used in this process are chemically synthesized; however, Chinese herbal polysaccharides offer a convenient, environmentally friendly, and non-toxic alternative, making them a prime candidate for actuating membrane preparation. The biological activities of chamomile polysaccharide (CP) include anti-inflammatory, lipid-lowering, sugar-lowering, and OH- clearance properties. Therefore, the actuating membrane of GBAM was prepared by crosslinking sodium alginate (SA) with CP. The findings indicated that at a crosslinking ratio of 4:5 for CP-SA, the electrically actuated force density and response speed reached 20.12 mN/g and 0.09 mN/g·s, respectively. Additionally, the working life extended to 781 seconds, tremor frequency decreased by 47.67%, and tremor amplitude was 19.55% of the control group. The elastic modulus was measured at 15.44 MPa, specific capacitance reached 183.99 mF/g, and internal resistance decreased by 13.44%. Charge and discharge time was 5.73 seconds, maximum energy reached 2.7 J, and specific energy was 12.66 A·J/g, representing increases of 2.3 seconds, 64.63%, and 6.47 A·J/g compared to the control group. The deflection displacement of 6.62 mm in the CP-SA group at a crosslinking ratio of 4:5 was found to be 3.06 times greater than that of the control group. In conclusion, the actuating membrane of GBAM, synthesized through the cross-linking of CP with SA at a specific ratio, demonstrated superior properties. This innovation offers a novel perspective and direction for the advancement of GBAMs and is anticipated to significantly contribute to future developments in related fields.

Green synthesis of benzimidazole derivatives using copper(II)-supported on alginate hydrogel beads

The study addresses the challenge of developing sustainable and efficient catalytic systems for the synthesis of benzimidazole derivatives, which are of significant importance in the field of medicinal chemistry due to their diverse biological activities. The objective is to develop a recyclable and environmentally friendly catalyst utilizing copper(II)-loaded alginate hydrogel beads, which can facilitate the synthesis of these compounds while minimizing environmental impact. The preparation process entails crosslinking sodium alginate with copper(II) ions to form hydrogel beads, which are then washed and characterized through techniques such as scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Inductively coupled plasma (ICP), and Zeta potential to analyses the morphology, composition and porosity of the beads. The catalytic performance is evaluated through recycling tests, which demonstrate the catalyst's ability to maintain selectivity and activity over multiple reaction cycles. The Cu(II)-Alg hydrogel beads were used for synthesizing substituted benzimidazole derivatives in a water-ethanol solvent at room temperature. This method offers significant advantages, including extremely mild reaction conditions, short reaction times (<1 h), high yields (70–94 %), and ease of processing. The most significant results indicate that the Cu(II)-alginate catalyst exhibits a high loading capacity and retains its catalytic efficiency for at least 3 cycles, thereby highlighting its potential for sustainable applications in organic synthesis.

Ionically crosslinked sodium alginate – galactoxyloglucan hydrogel beads as a controlled release system for sustainable urea delivery

Ionically crosslinked sodium alginate – galactoxyloglucan hydrogel beads as a controlled release system for sustainable urea delivery

Sodium Alginate/MXene-Based Flexible Humidity Sensors with High-Humidity Durability and Application Potentials in Breath Monitoring and Non-Contact Human–Machine Interfaces

Flexible humidity sensors (FHSs) with fast response times and durability to high-humidity environments are highly desirable for practical applications. Herein, an FHS based on crosslinked sodium alginate (SA) and MXene was fabricated, which exhibited high sensitivity (impedance varied from 107 to 105 Ω between 10% and 90% RH), good selectivity, prompt response times (response/recover time of 4 s/11 s), high sensing linearity (R2 = 0.992) on a semi-logarithmic scale, relatively small hysteresis (~5% RH), good repeatability, and good resistance to highly humid environments (negligible changes in sensing properties after being placed in 98% RH over 24 h). It is proposed that the formation of the crosslinking structure of SA and the introduction of MXene with good conductivity and a high specific surface area contributed to the high performance of the composite FHS. Moreover, the FHS could promptly differentiate the respiration status, recognize speech, and measure fingertip movement, indicating potential in breath monitoring and non-contact human–machine interactions. This work provides guidance for developing advanced flexible sensors with a wide application scope in wearable electronics.

High-Performance Pomegranate-Like CuF2 Cathode Derived from Spent Lithium-Ion Batteries.

With the large-scale application of lithium-ion batteries (LIBs), a huge amount of spent LIBs will be generated each year and how to realize their recycling and reuse in a clean and effective way poses a challenge to the society. In this work, using the electrolyte of spent LIBs as solvent, we in situ fluorinate the conductive three-dimensional porous copper foam by a facile solvent-thermal method and then coating it with a cross-linked sodium alginate (SA) layer. Benefiting from the solid-electrolyte interphase (SEI) that accommodating the volume change of internal CuF2 core and SA layer that inhibiting the dissolution of CuF2, the synthesized CuF2@void@SEI@SA cathode with a pomegranate-like structure (yolk-shell) exhibits a large reversible capacity of ~535 mAh g-1 at 0.05 A g-1 and superb cycling stability. This work conforms to the development concept of green environmental protection and comprehensively realizes the unity of environmental, social and economic benefits.

Wearable photonic crystal double network hydrogel sensor based on structural color analysis

Abstract This paper introduces a high-toughness photonic crystal (PhCs) dual-network hydrogel sensor designed for mechanical sensing, which enables quantitative analysis of structural color using the HSB color space. The hydrogel achieves a maximum tensile strain of 250% under a tensile stress of 3.5 MPa, thanks to its dual-network structure comprising a covalently cross-linked polyacrylamide (PAM) network and an ionically cross-linked sodium alginate (SA) network. At an 80% tensile strain, the PAM-SA photonic crystal hydrogel displays a blue shift in the bandgap wavelength of over 130 nm and demonstrates a sensitivity of 1.69 nm/%. The analysis of the force-induced color change in the PAM-SA photonic crystal hydrogel utilized both RGB and HSB color spaces. In the HSB color space, the hue component (H) exhibited a strong linear correlation with strain (R2&gt;0.95), indicating the feasibility of quantitative structural color analysis using HSB. As a wearable sensor, the PAM-SA photonic crystal hydrogel precisely detects human motion via bandgap displacement (R2=0.989) and structural color change (R2=0.978). The PAM-SA PhCs hydrogel, featuring easily accessible color information and high sensitivity, has broad potential applications in wearable devices and mechanical sensors.

Polyphenolic truxillic acid crosslinked sodium alginate film with notable antimicrobial and biodegradable properties for food packaging

This work demonstrated an innovative antimicrobial and biodegradable food packaging film CBDA-10-SA which was prepared by crosslinking a natural polyphenolic truxillic acid (cyclobutane-dicarboxylic acid, CBDA-10) and sodium alginate (SA). The CBDA-10-SA film exhibited improved tensile strength (148 MPa) and UV shielding capabilities. The maximum thermal decomposition temperature was achieved of 249 °C. Compared to SA film, CBDA-10-SA showed increased antibacterial activities. In food packaging test, the CBDA-10-SA inhibited the rapid growth of potential of hydrogen (pH) value, slowed down the weight loss, reduced total plate count (TPC) value of pork, and delayed the spoilage process of pork. Notably, CBDA-10-SA displayed remarkable degradability in soil, with 60 % degrading in four weeks. In this study, CBDA-10-SA showed enhanced physicochemical and mechanical properties compared to traditional SA film. Those improvements make it anticipated to be used in not only food packaging but also mechanical, pharmaceutical, and agricultural fields.

Asymmetric Hydrogel Electrolyte Featuring a Customized Anode and Cathode Interfacial Chemistry for Advanced Zn-I2 Batteries.

An integrated asymmetric hydrogel electrolyte with a tailored composition and chemical structure on the cathode/anode-electrolyte interface is designed to boost the cost-effective, high-energy Zn-I2 battery. Such a configuration concurrently addresses the parasitic reactions on the Zn anode side and the polyiodide shuttle issue afflicting the cathode. Specifically, the Zn2+-cross-linked sodium alginate and carrageenan dual network (Carra-Zn-Alg) is adopted to guide the Zn2+ transport, achieving a dendrite-free morphology on the Zn surface and ensuring long-term stability. For the cathode side, the poly(vinyl alcohol)-strengthened poly(3,4-ethylenedioxythiophene)polystyrenesulfonate hydrogel (PVA-PEDOT) with high conductivity is employed to trap polyiodide and accelerate electron transfer for mitigating the shuttle effect and facilitating I2/I- redox kinetics. Attributing to the asymmetrical architecture with a customized interfacial chemistry, the optimized Zn-I2 cell exhibits a superior Coulombic efficiency of 99.84% with a negligible capacity degradation at 0.1 A g-1 and an enhanced stability of 10 000 cycles at 5 A g-1. The proposed asymmetric hydrogel provides a promising route to simultaneously resolve the distinct challenges encountered by the cathode and anode interfaces in rechargeable batteries.

Development of sulfonated graphite oxide incorporated poly(styrene sulfonic acid‐co‐malic acid) crosslinked sodium alginate membranes for pervaporation dehydration of isopropanol

AbstractPervaporation (PV) is a promising membrane‐based technology for dehydrating alcohols and separation of close‐boiling liquids. Poly(styrene sulfonic acid‐co‐maleic acid) (PSSAMA) crosslinked sodium alginate (NaAlg) membrane was developed, and was then modified by varying the mass% of sulfonated graphite oxide (SGO). Physicochemical properties of the resulting membranes were assessed using FTIR, WXRD, TGA, DSC, and SEM. The pervaporation study was carried out to assess membrane performance in dehydrating isopropanol. The membrane with 16 mass% of SGO exhibited the highest separation factor of 6025 and flux of 14.66 × 10−2 kg m−2 h−1 at 30°C for 10 mass% of water in the feed and were able to break the water–isopropanol azeotropic point. The activation energy for water permeation (Epw) was lower than that of isopropanol permeation (EIPA), indicating the high separation ability. Activation energies for total permeation (EP) and total diffusion (ED) ranged from 12.42 to 49.13 and 12.99 to 54.42 kJ mol−1, respectively. Negative enthalpy values (ΔHs) suggested Langmuir's sorption predominance for all membranes.Highlights The SGO incorporated crosslinked NaAlg composite membranes were prepared. The membrane containing 16 mass% of SGO showed the highest water uptake. Membrane with 16 mass% of SGO showed the highest flux and separation factor. All composite membranes showed excellent thermal and mechanical stability. Membrane with 16 mass% of SGO demonstrated excellent PV performance.

Synthesis of sodium alginate / polyvinyl alcohol / polyethylene glycol semi-interpenetrating hydrogel as a draw agent for forward osmosis desalination

Typically, hydrogels are described as three-dimensional networks of hydrophilic polymers that are able to capture a certain mass of water within their structure. Recently, hydrogels have been widely used as drawing agents in forward osmosis (FO) desalination processes. The major aim of this study is to prepare a novel semi-interpenetrating hydrogel by crosslinking sodium alginate (SA) and polyvinyl alcohol (PVA) by using the epichlorohydrin (ECH) crosslinker and polyethylene glycol (PEG) interpenetrated within the hydrogel’s network as a linear polymer. Based on the optimum composition of SA/PVA composite hydrogel obtained from our earlier research, the effect of various percentages of PEG on the response of the hydrogel was investigated. The optimal composition of SA/PVA/PEG hydrogel was characterized by scanning electron microscopy (SEM), compression strength testing, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The morphological and mechanical properties of the SA/PVA/PEG semi-interpenetrating hydrogel were also compared to those of the SA/PVA composite hydrogel. Moreover, the performance of the optimal SA/PVA/PEG hydrogel in a FO batch unit as a drawing agent was investigated based on the optimal operation conditions from our previous experiments. The results showed that the optimal PEG/polymer blend mass ratio was 0.25, which increased the swelling ratio (SR) (%) of the hydrogel from 645.42 (of the neat SA/PVA hydrogel) to 2683. The SA/PVA/PEG semi-interpenetrating hydrogel was superior to the SA/PVA copolymer hydrogel in pore structure and mechanical properties. Additionally, in terms of FO desalination, the achieved water flux by SA/PVA/PEG hydrogel is higher than that accomplished by SA/PVA hydrogel.

Constructing Dynamic Cross-Linking Networks as Durable Bifunctional Coating for Highly Stable Zinc Anodes.

The serious dendrite growth and H2O-induced side reactions on the Zn electrode lead to a significant fading in the cycling performance, hindering the development of commercial applications of aqueous Zn-ion batteries (AZIBs). Herein, a novel bifunctional network coating of dynamically cross-linking sodium alginate with trehalose has been rationally constructed on the Zn anode (Zn@AT). Firstly, the AT coating possesses abundant zinophilic oxygen-containing functional groups, which are able to induce uniform Zn2+ ion flux. Secondly, the AT coating as a solid barrier can effectively inhibit H2O-induced side reactions by lowering the activity of H2O molecules. More specially, based on the dynamic cross-linking, AT network coating is endowed with self-healing capacity during cycling for durable battery operation. Consequentially, Zn@AT anodes in symmetric cells can cycle stably for 2787 h at 2 mA cm-2/2 mAh cm-2, and even achieve a significantly long cycle performance of 1087 h at large charge/discharge depths of 10 mA cm-2/10 mAh cm-2. Moreover, the Zn@AT//MnO2 full cell shows excellent specific capacity of 175 mAh g-1 after 400 cycles. This study lights an effective strategy to enhance the durability of Zn electrodes in AZIBs.

Quick self-grown ternary supramolecules embedded in sodium alginate to fabricate ultralight sponge exhibiting superior flame retardancy

To mitigate environmental and health risks associated with the use of halogenated flame retardants, effective halogen-free solutions have been extensively explored. In this study, melamine/boric acid/phosphoric acid (MBP)‑sodium alginate (SA) sponge was synthesized by treating MBP ternary supramolecules with microwave irradiation via one-pot, facile, and speedy synthesis, obtaining an MBP-SA sponge, a polysaccharide biopolymer. Crosslinking of SA with Ca2+ ion formed an intact network, and this was confirmed using scanning electron microscopy (SEM). Thereafter, the flame retardancy of the as-synthesized SA/MBP sponge was investigated by exposing it to a spirit lamp and a Bunsen burner; the sponge remained intact for up to 540 s and 370 s, respectively, demonstrating the enhanced flame retardancy of MBP supramolecules in the SA/MBP sponge. The limiting oxygen index of the SA/MBP sponge was up to 62 %, demonstrating the self-extinguishing and thermal insulation properties of the as-synthesized sponge. The findings of this study provide insights for developing a new strategy to use SA/MBP sponges for fire protection.

Enhanced proton conductivity and mechanical stability of crosslinked sodium alginate as a biopolymer electrolyte membrane in fuel cell application

Abstract Nafion is a commercial polymer membrane that is commonly used in fuel cell systems, despite its major limitations such as high fuel crossover and high manufacture cost. The production of sodium alginate (SA) blended membrane with crosslinking agent (glutaraldehyde) and plasticizer (glycerol) is one of several current efforts to discover an alternative membrane with improved proton conductivity and mechanical properties. In this study, SA biomembranes were prepared using solution casting method and dried at a certain temperature. Then, the prepared membranes were immersed with 5% glycerol in different concentrations of glutaraldehyde. The cross-linked biomembranes underwent various tests such as liquid uptake, swelling ratio, ion exchange capacity, proton conductivity and mechanical stability. The best membrane achieved the highest proton conductivity with a value of 8.28 mS cm-1 and mechanical stability with a value of 218.00 MPa. Glutaraldehyde made a positive modification and had a beneficial impact on the characteristics of SA. The incorporation of glutaraldehyde and glycerol within the biopolymer notably improved the otherwise lacking mechanical properties of SA.

An innovative method for effective rubidium recovery from wastewater using tungsten-doped microsphere magnetic tin sulfide

We synthesized a novel tungsten-doping metal sulfide, K1.46W0.02Sn2.95S6.69 (KWTS), for the efficient recovery of rubidium ions (Rb+) from wastewater. KWTS showed a high adsorption capacity of 184.68 mg/g and a fast adsorption rate of 10 seconds for Rb+. It also had a high selectivity for Rb+ over other alkali metal ions and a wide pH range of applicability. By magnetizing and crosslinking KWTS with sodium alginate crosslinking, we obtained micron-sized spherical particulates of Fe3O4@KWTS, which retained the excellent adsorption performance of KWTS and facilitated the separation of the adsorbent from aqueous phase. Fe3O4@KWTS also exhibited extraordinary stability after repeated cycles. This work provides a new avenue for ultrafast Rb+ resource recovery from wastewater.

Hygroscopic assisted solar photo-thermal-electric conversion system for all-day power generation and daytime water collection

In the field of solar thermal electricity, it is difficult to achieve efficient solar energy utilization during the day and continuous power supply day and night at the same time. To address this issue, an integrated system for daytime photothermal power generation combined with waste hot water evaporation and nighttime hygroscopic exothermic power generation has been designed. The system consists of multifunctional composite hydrogel, thermoelectric generator, and hydrophilic porous foam from top to bottom. Among them, the multifunctional composite hydrogel is a crosslinked sodium alginate (SA) loaded with photothermal material polypyrrole (PPy) and hygroscopic material CaCl2, and the hydrophilic porous foam is a PDMS treated by pore-making and oxygen plasma. During the night, CaCl2 and SA in the hydrogel absorb ambient moisture and then release heat, causing the temperature difference between the two sides of the thermoelectric generator to generate electricity with a power of 15.1 mW m−2. During the day, PPy in the hydrogel converts sunlight into heat for the thermoelectric generator to generate electricity with a power of 141.8 mW m−2, and the waste heat of the thermoelectric generator is then used to evaporate the water in the porous PDMS with a rate of 1.311 kg m-2h−1, realizing the multi-stage utilization of solar energy with a high efficiency of 80 %. Therefore, this integrated system can not only use solar energy efficiently, but also generate electricity continuously day and night.

Preparation of Cross-Linked Sodium Alginate Microspheres with Different Metal Ions Using the Microfluidic Electrospray Technology.

Microspheres are micrometer-sized particles that can load and gradually release drugs via physical encapsulation or adsorption onto the surface and within polymers. In the field of biomedicine, hydrogel microspheres have been extensively studied for their application as drug carriers owing to their ability to reduce the frequency of drug administration, minimize side effects, and improve patient compliance. Sodium alginate (ALG) is a naturally occurring linear polysaccharide with three backbone glycosidic linkages. There are two auxiliary hydroxyl groups present in each of the moieties of the polymer, which have the characteristics of an alcohol hydroxyl moiety. The synthetic ALG units can undergo chemical cross-linking reactions with metal ions, forming a cross-linked network structure of polymer stacks, ultimately forming a hydrogel. Hydrogel microspheres can be prepared using a simple process involving the ionic cross-linking properties of ALG. In this study, we prepared ALG-based hydrogel microspheres (ALGMS) using a microfluidic electrodeposition strategy. The prepared hydrogel microspheres were uniformly sized and well-dispersed, owing to accurate control of the microfluidic electrospray flow. ALGMS cross-linked with different metal ions were prepared using a microfluidic electrospray technique combining microfluidic and high electric field, and its antimicrobial properties, slow drug release ability, and biocompatibility were investigated. This technology holds promise for application in advanced drug development and production.

Processing of millimeter-sized spherical ZrO2 granules through sodium alginate cross-linking and an assessment of their resultant properties

Processing of millimeter-sized spherical ZrO2 granules through sodium alginate cross-linking and an assessment of their resultant properties

A Bioactive Injectable Hydrogel Regulates Tumor Metastasis and Wound Healing for Melanoma via NIR-Light Triggered Hyperthermia.

Surgical resection remains the mainstream treatment for malignant melanoma. However, challenges in wound healing and residual tumor metastasis pose significant hurdles, resulting in high recurrence rates in patients. Herein, a bioactive injectable hydrogel (BG-Mngel) formed by crosslinking sodium alginate (SA) with manganese-doped bioactive glass (BG-Mn) is developed as a versatile platform for anti-tumor immunotherapy and postoperative wound healing for melanoma. The incorporation of Mn2+ within bioactive glass (BG) can activate the cGAS-STING immune pathway to elicit robust immune response for cancer immunotherapy. Furthermore, doping Mn2+ in BG endows system with excellent photothermal properties, hence facilitating STING activation and reversing the tumor immune-suppressive microenvironment. BG exhibits favorable angiogenic capacity and tissue regenerative potential, and Mn2+ promotes cell migration in vitro. When combining BG-Mngel with anti-PD-1 antibody (α-PD-1) for the treatment of malignant melanoma, it shows enhanced anti-tumor immune response and long-term immune memory response. Remarkably, BG-Mngel can upregulate the expression of genes related to blood vessel formation and promote skin tissue regeneration when treating full-thickness wounds. Overall, BG-MnGel serves as an effective adjuvant therapy to regulate tumor metastasis and wound healing for malignant melanoma.

Bioremediation of 2,4,6-trichlorophenol by extracellular enzymes of white rot fungi immobilized with sodium alginate/hydroxyapatite/chitosan microspheres

Hydroxyapatite, a calcium phosphate biomass material known for its excellent biocompatibility, holds promising applications in water, soil, and air treatment. Sodium alginate/hydroxyapatite/chitosan (SA-HA-CS) microspheres were synthesized by cross-linking sodium alginate with calcium chloride. These microspheres were carriers for immobilizing extracellular crude enzymes from white rot fungi through adsorption, facilitating the degradation of 2,4,6-trichlorophenol (2,4,6-TCP) in water and soil. At 50 °C, the immobilized enzyme retained 87.2% of its maximum activity, while the free enzyme activity dropped to 68.86%. Furthermore, the immobilized enzyme maintained 68.09% of its maximum activity at pH 7, surpassing the 51.16% observed for the free enzyme. Under optimal conditions (pH 5, 24 h), the immobilized enzymes demonstrated a remarkable 94.7% removal rate for 160 mg/L 2,4,6-TCP, outperforming the 62.1% achieved by free crude enzymes. The degradation of 2,4,6-TCP by immobilized and free enzymes adhered to quasi-first-order degradation kinetics. Based on LC-MS, the plausible biodegradation mechanism and reaction pathway of 2,4,6-TCP were proposed, with the primary degradation product identified as 1,2,4-trihydroxybenzene. The immobilized enzyme effectively removed 72.9% of 2,4,6-TCP from the soil within 24 h. The degradation efficiency of the immobilized enzyme varied among different soil types, exhibiting a negative correlation with soil organic matter content. These findings offer valuable insights for advancing the application of immobilized extracellular crude enzymes in 2,4,6-TCP remediation.

L-Cysteine Cross-Linked Sodium Alginate as a Binder with Strong Binding Force on Copper Foils To Enhance Sodium Storage Performance

<i>L</i>-Cysteine Cross-Linked Sodium Alginate as a Binder with Strong Binding Force on Copper Foils To Enhance Sodium Storage Performance