Alginate Aerogels Research Articles

Regulation of Adsorption Properties of Whey Protein Isolate Fibril-Calcium Alginate Aerogels by Controlling Protein Fibrillation Time.

Amyloid-like fibrils have a relatively high specific surface area, which makes them suitable as absorbents. In this study, we prepared absorbent composite aerogels from whey protein isolate fibril (WPIF) and calcium alginate (CA). The impact of protein fibrillation time (4-24 h) on the adsorption properties of these aerogels was assessed, as this influences the nature of the WPIFs formed. Fourier transform infrared spectroscopy analysis indicated that hydrogen bonding, hydrophobic interactions, and electrostatic interactions were the main molecular interactions in the composite aerogels. Then, the adsorption properties of the aerogels were investigated using crystal violet as a model compound. The adsorption properties of all composite aerogels were significantly improved compared to CA aerogels, which was mainly attributed to the numerous functional groups of the surfaces of the WPIFs, as well as the rougher surface topology of the composite aerogels. The adsorption capacity of the composite aerogels first increased and then decreased with increasing fibrillation time, with 8 h fibrillation leading to the largest adsorption capacity (1886.11 mg/g). Thioflavin T fluorescence, atomic force microscopy, light extinction, average particle size, and zeta potential analysis indicated that the high fibril content, mature fibril morphology, large number of available functional groups on the surface, and relatively low zeta potential of WPIF8 might be the main reasons. Adsorption kinetics and isothermal adsorption profile analysis suggested that monolayer adsorption occurred through chemical adsorption processes. The edible aerogel with high adsorption properties developed in this work has potential application in food and biomedical fields.

Defect-Engineered MOF-801/Sodium Alginate Aerogel Beads for Boosting Adsorption of Pb(II).

Metal-organic frameworks (MOFs) are attractive adsorbents for heavy metal capture due to their superior stability, easy modification, and adjustable pore size. However, their inherent microporous structure poses challenges in achieving a higher adsorption capacity. Defect engineering is considered a simple method to create hierarchical MOFs with larger pores. Here, we employed l-aspartic acid as a mixed linker to bind Zr4+ clusters in competition with fumaric acid of MOF-801 to create defects, and the pore size was increased from 4.66 to 15.65 nm. Mercaptosuccinic acid was subsequently used as a postexchange ligand to graft the resultant MOF-801 by acid-ammonia condensation to further expand the pore size to 22.73 nm. Notably, the -NH2, -COOH, and -SH groups contributed by these two ligands increased the adsorption sites for Pb(II). The obtained defective MOF-801 with larger pores was thereafter loaded onto sodium alginate to form aerogel beads as adsorbents, and an adsorption capacity of 375.48 mg/g for Pb(II) was achieved, which is ∼51 times that of pristine MOF-801. The aerogel beads also exhibited outstanding reusability with a removal efficiency of ∼90.23% after 5 cycles of use. The adsorption mechanism of Pb(II) included ion-exchange interaction, as well as chelation interactions of Pb-O, Pb-NH2, and Pb-S. The versatile combination of defect engineering and composite beads provides novel inspirations for MOF modification for boosting heavy metal adsorption.

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

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

Advanced alginate-based nanofiber aerogels: A synthetic matrix for high-efficiency lysozyme adsorption and controlled release

The development of materials with high lysozyme adsorption is critical for drug delivery and skin wound applications, as it enhances antibacterial properties, stability, and controlled release of therapeutic agents, thereby improving treatment efficacy and safety. Alginate-based nanofiber scaffolds, featuring high surface area and multiple adsorption sites, can efficiently absorb lysozyme and regulate its release through tunable pore channels, offering a promising approach to chronic wound management. In this study, we fabricated poly (vinyl alcohol-co-ethylene) (EVOH) nanofiber-based sodium alginate (ENSA) aerogels using a simple two-step crosslinking procedure. The resulting aerogels, with controllable porosity formed via high-pressure spraying techniques (aerogel film) and molding (aerogel sponge), were evaluated for their high-loading capacity and controllable release of lysozyme. The aerogel film exhibited a remarkable lysozyme adsorption capacity of 1965 ± 36 mg/g, while the aerogel sponge sustained lysozyme release over 14 days. Analysis of the drug-release mechanism through four kinetic models revealed two distinct processes: cation exchange and matrix diffusion. The aerogel's pore structure influenced the diffusion processes, enabling tailored drug release profiles. Additionally, the ENSA aerogels demonstrated good mechanical properties, non-cytotoxicity, and potent antibacterial activity, positioning them as promising materials for skin wound dressings.

Preparation and characterization of polyethylene glycol/sodium alginate aerogel beads loaded with biogenic zinc oxide nanoparticles: potential therapeutic option for treating multidrug-resistant bacteria and cytotoxic activity

Preparation and characterization of polyethylene glycol/sodium alginate aerogel beads loaded with biogenic zinc oxide nanoparticles: potential therapeutic option for treating multidrug-resistant bacteria and cytotoxic activity

Truffle mediated preparation of bacterial culture medium and mycosynthesis of titanium oxide nanoparticles loaded with polyvinyl alcohol/sodium alginate aerogel beads for antibacterial activity

Truffle mediated preparation of bacterial culture medium and mycosynthesis of titanium oxide nanoparticles loaded with polyvinyl alcohol/sodium alginate aerogel beads for antibacterial activity

Encapsulation of Bamboosa vulgaris culms derived activated biochar into hierarchical permeable, phosphate rich and functionalized alginate aerogel composites and its contribution in U(VI) adsorption

In this study, a facile methodology was designed to encapsulate Bamboosa vulgaris culms derived activated biochar (BVC) in a variable mass ratio, into a three-dimensional hierarchical porous and permeable and amino-thiocarbamated alginate (TSC) to prepare hybrid biosorbents (BVC-MSA). These ultralight and lyophilized phosphate rich macroporous sorbents were rationally characterized through FTIR, XRD, BET, SEM-EDS, elemental mapping, XPS techniques and employed for efficient UO22+ adsorption from aqueous solutions. The phytic acid (PA) was found to be a suitable hydrophilic and phosphorylating agent for the TSC matrix through hydrogen-bonded crosslinking when employed in a correct mass ratio (1:3). The SEM-EDS and XPS analyses confirmed the UO22+ sorption onto BVC-MSA-3 (the most suitable composite with a BVC/TSC mass ratio of 30.0 % w/w) and provided evidence of heteroatom involvement in developing the physico-chemical interactions. The BCV-MSA-3 exhibited the best response as a sorbent during kinetics/sorption process, therefore, it was selected to study the equilibrium sorption studies. The BCV-MSA-3 removal efficiency increased from 12.1 to 94.2 % using 0.2 to 1.8 g/L sorbent dose at pH (4.5). The mentioned sorbent displayed a significant maximum sorption capacity qm (309.55 mg/g at 35 °C) calculated through the best-fitted Langmuir and Temkin models (R2 ≈ 0.99). The sorption kinetics followed the pseudo-second-order (PSORE) model and exhibited fast sorption rate teq (180 min). Thermodynamic parameters clarified that the sorption process is feasible ΔGo (−25.3 to −27.6 kJ/mol kJ/mol), endothermic ΔHo (27.17 kJ/mol), and proceeds with a positive entropy (0.176 kJ/mol.K). The study shows that BCV-MSA-3 could be an alternative and auspicious sorbent for uranium removal from aqueous solution.

Fire-resistant and thermal-insulating alginate aerogel with intelligent bionic armor for exceptional mechanical and fire early-warning performance

Intelligent bio-based aerogels have attracted increasing attention in several key areas due to their unique porous structure and sustainability, but they suffer from poor fire safety, strength, and durability under harsh conditions. Here, we prepared sodium alginate/hydroxyapatite/graphene oxide (SA@HAP@GO) aerogel by in-situ growth and directional assembly technology, and an intelligent “bionic armor” was put on the surface of SA aerogel. It not only endows aerogel with high strength (2.3 MPa) and long-time water resistance (30 days) but also maintains the lightweight (0.039 g cm−3) and thermal insulation properties (0.03537 W m-1K−1) of original aerogel. Under fire conditions, the compact physical barrier makes aerogel obtain the excellent fire-resistant stability and fire-safety performance. Besides, the directional assembly of GO and the chelating effect of Ca2+ on aerogel surface promote the formation of a three-dimensional electron transport network during reduction process, thus achieving a fast and long-lasting fire early-warning response (1.95 s). The corresponding mechanism was demonstrated by molecular theoretical calculation and experiments. This multifunctional aerogel provides a new way for sustainable and high-performance thermal-insulation materials and shows a wide application in energy security.

Radially and Axially Oriented Ammonium Alginate Aerogels Modified with Clay/Tannic Acid and Crosslinked with Glutaraldehyde.

Lightweight materials that combine high mechanical strength, insulation, and fire resistance are of great interest to many industries. This work explores the properties of environmentally friendly alginate aerogel composites as potential sustainable alternatives to petroleum-based materials. This study analyzes the effects of two additives (tannic acid and montmorillonite clay), the orientation that results during casting, and the crosslinking of the biopolymer with glutaraldehyde on the properties of the aerogel composites. The prepared aerogels exhibited high porosities between 90% and 97% and densities in the range of 0.059-0.191 g/cm3. Crosslinking increased the density and resulted in excellent performance under loading conditions. In combination with axial orientation, Young's modulus and yield strength reached values as high as 305 MPa·cm3/g and 7 MPa·cm3/g, respectively. Moreover, the alginate-based aerogels exhibited very low thermal conductivities, ranging from 0.038 W/m·K to 0.053 W/m·K. Compared to pristine alginate, the aerogel composites' thermal degradation rate decreased substantially, enhancing thermal stability. Although glutaraldehyde promoted combustion, the non-crosslinked aerogel composites demonstrated high fire resistance. No flame was observed in these samples under cone calorimeter radiation, and a minuscule peak of heat release of 21 kW/m2 was emitted as a result of their highly efficient graphitization and fire suppression. The combination of properties of these bio-based aerogels demonstrates their potential as substituents for their fossil-based counterparts.

Vertically aligned aerogel with concaved surface topography coupled ordered channel enable efficient solar-driven desalination

Solar-driven desalination has been regarded as a promising energy-saving and sustainable strategy to address the serious freshwater shortage issue. However, its performance is restricted by low solar energy utilization efficiency, water transport, and serious salt deposition. Herein, an efficient solar-driven interfacial evaporator with high solar energy utilization efficiency, fast water transport and robust salt tolerance was developed, via constructing vertically aligned sodium alginate (SA) aerogel with concave surface topography coupled ordered water transport channel structure. Concaved reflecting valley surface was assembled with 3D hierarchical photothermal networks of 2D MXene synergistic 1D carbon nanotube to enhance light absorption capacity. Concaved surface topography with multiple reflective nanostructure (angle 45°, depth 1.5 cm) owns strong sunlight concentration performance, which effectively avoid the light loss and thus enhance the light-absorption over a broad spectrum (0.3–2.5 μm). In another way, hydrophilic SA aerogel with vertically aligned structure, which also provides ordered channels for fast water/vapor transport and high salt rejection ability via strong wicking and diffusion effect. Solar-driven interfacial evaporator with such unique concaved surface topography that coupled ordered valley channels exhibits excellent evaporation rate (2.81kg m−2h−1) and remarkable solar energy utilizing efficiency (98.52 %), while with excellent antibacterial ability during continuously desalination process. Solar-driven interfacial evaporator with unique concaved surface topography coupled ordered valley channels holds great potential in sustainable water purification and desalination.

Preparation of multifunctional polypyrrole hydrogel/Fe3O4/calcium alginate composite aerogel with electromagnetic shielding and fire warning performance

Purpose This study aims to fabricate a novel electromagnetic interference (EMI) shielding composite aerogel with both thermal insulation and high temperature warning functions. Design/methodology/approach An emerging bio-based polypyrrole (PPy) gel/Fe3O4/calcium alginate (PFC) EMI shielding composite aerogel was prepared by freeze-drying and in situ polymerization method. First, Fe3O4/calcium alginate (CA) aerogel was obtained by freeze-drying the Fe3O4/CA mixture. Then, PPy/Fe3O4/CA was obtained by synthesizing PPy on the surface of CA/Fe3O4 aerogel through in situ polymerization. Finally, PPy/Fe3O4/CA was immersed in porphyrin solution (cross-linking agent) to get the final PFC EMI shielding composite aerogel. Findings Due to the matched impedance between Fe3O4 and PPy, the EMI shielding performance of PFC composite aerogel can reach up to −8 dB. In addition, the PFC EMI shielding composite aerogel also shows excellent self-extinguishing and thermal insulation properties. After leaving the flame, the burning PFC aerogel is quickly extinguished. When the PFC aerogel is placed on the heating plate at 230 °C, the temperature on the side of the aerogel away from the heating plate is only 90.3 °C after 5 min of heating. The electrical resistance of the PFC composite aerogel can be reduced from 3.62 × 104 O to 5 × 102 O to trigger the warning light after 3 s of exposure to the alcohol lamp flame. This reversible thermal resistance response characteristic can be used to give an early warning signal when the PFC encounters high temperature or flame. Originality/value This work provides a novel strategy for designing a multifunctional EMI shielding composite aerogel with repeatable high temperature warning performance. This PFC composite aerogel shows potential applications in the prevention of material combustion in high temperature electromagnetic environments.

MXene Sediment-Based Poly(vinyl alcohol)/Sodium Alginate Aerogel Evaporator with Vertically Aligned Channels for Highly Efficient Solar Steam Generation

HighlightsMXene sediments is innovatively used as photothermal material for seawater desalination.Inspired by the natural wood transpiration process, a 3D MXene sediment-based aerogel with vertically aligned channels is innovatively prepared as solar evaporator.With unique structure and composition, excellent photothermal conversion efficiency, evaporation rate, salt resistance, and resistance to biological/oil/special environments are achieved in practical desalination.

Integration of N- and P- elements in sodium alginate aerogels for efficient flame retardant and thermal insulating properties

In the field of building energy conservation, the development of biodegradable biomass aerogels with excellent mechanical performance, flame retardancy and thermal insulation properties is of particular importance. Here, a directional freeze-drying method was used for fabricating composite sodium alginate (SA) aerogels containing functionalized ammonium polyphosphate (APP) flame retardant. In particular, APP was coated with melamine (MEL) and phytic acid (PA) by a supramolecular assembly process. Through optimizing the flame retardant addition, the SA-20 AMP sample exhibited excellent flame retardant and thermal insulation properties, with the limiting oxygen index of 38.2 % and the UL-94 rating of V-0. Such aerogels with anisotropic morphology demonstrated a low thermal conductivity of 0.0288 (W/m·K) in the radial direction (perpendicular to the lamellar structure). In addition, as-obtained aerogels displayed remarkable water stability and mechanical properties, indicating significant potential for practical applications.

3D macroporous MXene/sodium alginate aerogels with “brick-concrete” structures for highly efficient solar-driven water purification

Interfacial water evaporation, powered by solar energy, holds great promise to extract freshwater from seawater on a global scale. It has the potential to address the world's water scarcity challenges using renewable energy. While the ideal design of evaporator materials is critical to the interfacial vaporization desalination, tailoring the structures and compositions of solar evaporators and figuring out the structure/composition-performance relationship of evaporators remains unexplored. Herein, 3D macroporous “brick-concrete” MXene/sodium alginate aerogel (MSA) evaporators were designed and fabricated with constant MXene content and varying polymer loading. The as-made MSAs show sodium alginate-dependent evaporating performance with an optimum evaporation rate of 3.28 kg m−2 h−1 (1 sun). This exceptional rate is attributed to several factors, including enhanced light absorption, optimized pore sizes, reduced enthalpy of evaporation and improved water transport. The water molecule states and hydrogen bonding network in the aerogels can be tuned by their compositions, resulting in the reduced evaporation enthalpy, the monolithic structures with controlled thermal conductivity facilitate the exploitation of environmental energy, leading to the high evaporation rate. Our study not only establishes design principles for achieving superior evaporation performance, but also sheds light on the relationship between structures, compositions, and performance of solar evaporators.

Performance and Mechanism of L-arginine Modifed Alginate Aerogels for Adsorption of Cadmium and Copper Ions

Performance and Mechanism of L-arginine Modifed Alginate Aerogels for Adsorption of Cadmium and Copper Ions

A macromolecular cross-linked alginate aerogel with excellent concentrating effect for rapid hemostasis

Alginate-based materials present promising potential for emergency hemostasis due to their excellent properties, such as procoagulant capability, biocompatibility, low immunogenicity, and cost-effectiveness. However, the inherent deficiencies in water solubility and mechanical strength pose a threat to hemostatic efficiency. Here, we innovatively developed a macromolecular cross-linked alginate aerogel based on norbornene- and thiol-functionalized alginates through a combined thiol-ene cross-linking/freeze-drying process. The resulting aerogel features an interconnected macroporous structure with remarkable water-uptake capacity (approximately 9000 % in weight ratio), contributing to efficient blood absorption, while the enhanced mechanical strength of the aerogel ensures stability and durability during the hemostatic process. Comprehensive hemostasis-relevant assays demonstrated that the aerogel possessed outstanding coagulation capability, which is attributed to the synergistic impacts on concentrating effect, platelet enrichment, and intrinsic coagulation pathway. Upon application to in vivo uncontrolled hemorrhage models of tail amputation and hepatic injury, the aerogel demonstrated significantly superior performance compared to commercial alginate hemostatic agent, yielding reductions in clotting time and blood loss of up to 80 % and 85 %, respectively. Collectively, our work illustrated that the alginate porous aerogel overcomes the deficiencies of alginate materials while exhibiting exceptional performance in hemorrhage, rendering it an appealing candidate for rapid hemostasis.

Conductive copper ion-reinforced sodium alginate aerogel based free-standing Si anode for Li-ion storage

Biomass materials with great advantages of wide accessibility, low cost and environmental benignity have favorable application prospects as Si anodes for lithium-ion batteries (LIBs). In order to alleviate the volume effect and improve the conductance of Si, we fabricated a conductive copper ion-reinforced sodium alginate (SA) aerogel based free-standing Si anode (Si@CNTs/Alg-Cu-II) containing silicon nanoparticles, sodium alginate aerogel, carbon nanotubes and Cu nanoparticles, via a simple, low-cost and sustainable process (under 1 × 10−1 Pa, 1 °C/min to 200 °C holding for 1 h). In the irregular lamellar porous aerogel, silicon particles with good dispersion are bound by macromolecular chains of SA via dynamic hydrogen bonds and subsequently restrained in the porous aerogel to release volume stress. The in situ generated Cu particles and well-dispersed carbon nanotubes (CNTs) construct the conductive network around Si particles to improve the electrical conductivity of the electrode. This unique structure delivers a capacity of 835.6 mAh/g after 100 cycles at 0.1 A/g based on the total mass of Si@CNTs/Alg-Cu-II composite (Si content of 25.62%). Moreover, it also shows outstanding stability under high current density (a capacity retention of 84.1% after 100 cycles at 0.5 A/g). The sustainable preparation method and excellent electrochemical performance of Si@CNTs/Alg-Cu-II provide a new strategy to develop high-performance free-standing Si-based anodes for LIBs.

Wetting of alginate aerogels, from mesoporous solids to hydrogels: a small-angle scattering analysis

Mesoporous polysaccharide aerogels are versatile functional materials for drug delivery and wound dressing devices. The hydration and wetting of these aerogels control their application-related performance, e.g. the release of encapsulated drugs. Reported here is a detailed small-angle neutron scattering (SANS) analysis of the hydration mechanism of a calcium alginate aerogel, based on mathematical modelling of the scattering. The model accounts for the hierarchical structure of the material comprising a mesoporous structure, the solid skeleton of which is made up of water-swollen polymers. At large scale, the mesoporous structure is modelled as a random collection of elongated cylinders, which grow in size as they absorb water and aggregate. The small-scale inner structure of the skeleton is described as a Boolean model of polymer coils, which captures the progressive transition from a dense dry polymer to a fully hydrated gel. Using known physico-chemical characteristics of the alginate, the SANS data are fitted using the size of the cylinders as the only adjustable parameter. The alginate aerogel maintains a nanometre-scale, albeit altered, structure for low water contents but it collapses into micrometre-sized structures when the water content approaches one gram of water per gram of alginate. In addition to the wetting of aerogels, the model might be useful for the small-angle scattering analysis of the supercritical drying of gels.

Effect of metal organic framework alginate aerogel composite sponge on adsorption of tartrazine from aqueous solutions: Adsorption models, thermodynamics and optimization via Box-Behnken design

La-MOF has an excellent chance of eliminating food and industrial coloring pollutants from water because it is a typical metal-organic framework material. Nevertheless, the challenging liquid recovery has restricted the use of this powdered adsorbent. In order to solve this shortcoming, we created composite beads (La-MOF@CA aerogel composite sponge) by solidifying sodium alginate and La-MOF together. A common technique to boost an adsorbent material's adsorption capability is to modify its composition; this is especially true for adsorbents composed of metal organic framework. The effects of La-MOF@CA aerogel composite sponge on the adsorption and elimination of tartrazine (TZ) were examined in this study. Following thorough characterization, the following tests were performed: X-ray diffraction (XRD), energy-dispersive X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller surface area (BET). The La-MOF@CA aerogel composite sponge has a significant high surface area of 1244.68 m2/g and this surface area was decrease after adsorption of TZ to be 768.98 m2/g. the greatest adsorption capacity (qmax) of for TZ, 710.75 mg/g. Examine how the adsorption process is impacted by factors like temperature, adsorbent dosage, pH, and TZ concentration. The pHZPC was 5.18 and optimum pH for adsorption and removal of TZ was 4. The adsorption process was fitted to the pseudo-second-order equation kinetically, and to the Langmuir equation isothermally. As the adsorption energy Ea was 22.76 kJ/mol indicated that the adsorption process was chemisorption. The adsorption process was thought to be endothermic and spontaneous based on adsorption thermodynamics. The temperature increased in tandem with the amounts of materials absorbed. With good efficiency, no change in chemical composition, and similar XRD and XPS data before and after reuse, the La-MOF@CA aerogel composite sponge was reused five times. Examine the interaction mechanism between the heavy TZ and the La-MOF@CA aerogel composite sponge. Box Behnken-design was used to maximize the adsorption results (BBD).

Alginate aerogels by spray gelation for enhanced pulmonary delivery and solubilization of beclomethasone dipropionate

Aerogel technology is an emerging platform that offers alternative and cost-effective dry carriers with advanced performances for the pharmaceutical industry. The innovative combination of compressed air-assisted spray gelation and “green” supercritical fluid (SCF) technology was used in this study to produce alginate aerogel microparticles with adequate properties for pulmonary drug delivery. Beclomethasone dipropionate (BDP), a poorly water-soluble anti-inflammatory drug for asthma treatment, was loaded into alginate aerogel particles by SCF-assisted impregnation ensuring high loading, as well as the amorphization of the drug. The production of aerogels was optimized through the fine-tuning of parameters in compressed air-assisted spray gelation, specifically adjusting the air flow rate and the pump speed. Alginate aerogels were aimed to be produced with an appropriate aerodynamic diameter from 1 to 5 µm, measured by in vitro deposition tests with Next Generation impactor and potential for deep lung penetration. Nuclear magnetic resonance (NMR) relaxometry was used to assess aerogel hydration and unveiled structure–property relationships leading to the sudden release of the drug. Finally, in vitro cytotoxicity tests in fibroblasts and ex vivo permeability tests were conducted. These biological tests confirmed the excellent biocompatibility of the aerogel formulations and demonstrated the efficient deposition of BDP in porcine bronchial tissues assisted by the porous alginate aerogel carrier.