Calcium Alginate Hydrogel Research Articles

Chemically Crosslinked Alginate Hydrogel with Polyaziridine: Effects on Physicochemical Properties and Promising Applications.

Alginate biopolymer is widely employed in many industrial fields thanks to its pleasing features of biodegradability, biocompatibility, low toxicity, and relatively low cost. The gelling process of alginate with divalent cations is fairly simple and thus it is used as a versatile biomaterial to tailor the desired mechanical and moisture properties. This study focused on developing new gel formulations to enhance the properties of calcium-alginate hydrogel (CA). The newly synthesized hydrogels, referred to as CA-CHEM gels, were chemically cross-linked with different ratios of pentaerythritol tris[3-(1-aziridinyl)propionate] (PTAP) through the reaction between the carboxylic groups of alginate and aziridines of PTAP. The reaction was successfully monitored by NMR. The new CA-CHEM gels were chemically characterized using FTIR-ATR, while SEM analysis confirmed the changes in the porosity and homogeneity of the network. Additionally, thermogravimetric analyses and mechanical properties showed improvement in degradation stability and in structural strength, compared to plain CA, with an increasing PTAP content up to 1% w/w. Finally, the new CA-CHEM gels effectively controlled water absorption and release. In particular, CA-CHEM-1 performed as the most controlled system, making it promising for delivering aqueous cleaning solutions on water-sensitive surfaces such as a wooden historical musical instrument.

Cellulase entrapment in calcium alginate hydrogel beads for improved reusability and hydrolysis of cellulosic biomass

Cellulase entrapment in calcium alginate hydrogel beads for improved reusability and hydrolysis of cellulosic biomass

Enhanced catalytic efficiency and ionic liquid tolerance of entrapped cellulase for single-step mixed cabbage residue saccharification

This study explores the enhancement of catalytic efficiency and 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) tolerance in the single-step saccharification of mixed cabbage residue (MCR) biomass using entrapped cellulase. Entrapping cellulase in calcium alginate hydrogel beads achieved an entrapment efficiency of 75.90 ± 1.83 %. In hydrolysis systems with 2 % and 10 % [Emim][OAc], the entrapped cellulase demonstrated 5.3 % and 6.5 % higher activity than free cellulase, respectively. After five cycles, the entrapped cellulase retained 93 % and 87 % of its initial activity in 0 % and 2 % [Emim][OAc] hydrolysis systems, respectively. Remarkably, cumulative glucose yields with entrapped cellulase were 3.51 and 3.10 times greater than those with free cellulase in 0 % and 2 % [Emim][OAc] hydrolysis systems, respectively. These results highlight the superior performance of entrapped cellulase in maintaining enzyme activity and improving glucose yields. Notably, while [Emim][OAc] is effective in separate pretreatment stages, its addition is unnecessary for the single-step saccharification of MCR biomass. This study underscores the promising potential of entrapped cellulase as a catalyst in enhancing the efficiency of biomass saccharification processes.

Sensitivity-enhanced optical fiber probe-type humidity sensor based on CaAlg film

Optical fiber probe-type humidity sensors based on calcium alginate (CaAlg) hydrogel films are proposed. The sensor is based on the Michelson interferometer (MI) and constructed by splicing a tapered multimode fiber (MMF) in the middle of two single-mode fibers (SMFs). One of the 1.5 cm long SMFs is coated with CaAlg hydrogel film and can be regarded as the sensor probe. The sensitivity of the sensor is 0.31015 nm/%RH. The high sensitivity, low temperature crosstalk, compact probe structure, and stability of the sensor allow it to be used for humidity monitoring in a variety of complex environments.

Durable fluorinated cobalt oxyhydroxide/calcium alginate hydrogels for activating peroxymonosulfate to enable nearly 100% degradation of ciprofloxacin.

Peroxymonosulfate (PMS) activation by solid catalysts for ciprofloxacin (CIP) removal is a promising method for decontaminating wastewater. However, mainstream catalysts suffer from efficiency and durability issues due to mechanical fragility and structural instability. Here, we have developed a durable calcium alginate hydrogel encapsulating fluorinated cobalt oxyhydroxide (FCO/CAH), fabricated by a simple hydrogen-bond-assisted cross-linking reaction, to enhance PMS activation for complete CIP removal. The optimized 2-FCO/CAH could generate abundant singlet oxygen (1O2) and sulfate radicals (SO4˙-) with PMS, resulting in 0.433 min-1 kinetic constant and approximately 100% CIP degradation within 10 minutes. This exceptional degradation efficiency is due to the even distribution of 2-FCO, which maximizes catalytic sites for PMS activation, and the multichannel cavity structure of CAH, which effectively enriches both PMS and CIP. Furthermore, the durability of 2-FCO/CAH was proved by its negligible decay in CIP removal efficiency (∼100%) and good microstructure retention after 6 consecutive cycles, facilitated by a stable surface reconstructed interphase on the 2-FCO surface and the strong mechanical property of 2-FCO/CAH. Our work showcases a facile approach to constructing durable hydrogel catalysts that improve PMS-mediated antibiotic degradation.

High-strength, super-hydrophilic alginate electrospun nanofibrous membranes for rapid oil-water emulsion separation

Ultrafiltration membrane separation technology is considered an effective method for separating oil-water emulsions. However, oil droplets can easily deposit on the surface of the membranes, leading to severe fouling and a decrease in flux. In this study, poly (ethylene oxide)/acrylamide/sodium alginate (PEO/AM/NaAlg) hydrogel nanofibers were deposited on a poly (hydroxybutyric acid) (PHB) electrospun nanofibrous membrane. Subsequently, superhydrophilic (ethylene oxide)-poly(acrylamide)/calcium alginate hydrogel nanofiber composite filtration membranes (PEO/PAM/CaAlg-PHB) were prepared by polymerization and Ca2+ cross-linking using a PHB electrospun nanofibrous membrane as the matrix. The morphology, tensile strength, water contact angle, and oil–water emulsion separation properties of the PEO/PAM/CaAlg-PHB hydrogel filtration membrane were investigated. The results showed that the PEO/PAM/CaAlg-PHB membrane had good anti-fouling performance, with a tensile strength of 1.95 MPa. After 3 h of the filtration operation, the stable flux and oil–water emulsion rejection of the membrane reached 2925.2 L m−2 h−1 bar−1 and 98.66 %, respectively. The preparation method was simple, cost effective, and environmentally friendly, without introducing any organic pollutants. The PEO/PAM/CaAlg-PHB hydrogel filtration membrane shows promise for separating oil–water emulsions.

Cartilage defect repair in a rat model via a nanocomposite hydrogel loaded with melatonin-loaded gelatin nanofibers and menstrual blood stem cells: an in vitro and in vivo study

Cartilage damage caused by injuries or degenerative diseases remains a major challenge in the field of regenerative medicine. In this study, we developed a composite hydrogel system for the delivery of melatonin and menstrual blood stem cells (MenSCs) to treat a rat model of cartilage defect. The composite delivery system was produced by incorporation of melatonin into the gelatin fibers and dispersing these fibers into calcium alginate hydrogels. Various characterization methods including cell viability assay, microstructure studies, degradation rate measurement, drug release, anti-inflammatory assay, and radical scavenging assay were used to characterize the hydrogel system. MenSCs were encapsulated within the nanocomposite hydrogel and implanted into a rat model of full-thickness cartilage defect. A 1.3 mm diameter drilled in the femoral trochlea and used for the in vivo study. Results showed that the healing potential of nanocomposite hydrogels containing melatonin and MenSCs was significantly higher than polymer-only hydrogels. Our study introduces a novel composite hydrogel system, combining melatonin and MenSCs, demonstrating enhanced cartilage repair efficacy, offering a promising avenue for regenerative medicine.Graphical

Effect of microplastic ingredient on the removal of microplastics by calcium alginate flocculation

The widespread presence of microplastics induce a serious threat to the survival of living organisms. Herein, calcium alginate hydrogel was selected as a flocculant to remove microplastics from water. To determine the variability of the flocculation method for the removal of microplastics with different properties, 11 microplastics of different sizes or components were used. The results showed the removal of different microplastics were 99.5% (PSMP 5 µm), 99.5% (24 h aged PSMP), 98.6% (72 h aged PSMP), 97.1% (48 h aged PSMP), 92.0% (PMMA 15 µm), 84.0% (PAMP 5 µm), 82.0% (PVCMP 1 µm), 80.2% (PLAMP 500 mesh), 68.0% (PEMP 100 mesh), 52.0% (PE 20 µm), and 52.0% (PP 1000 mesh). Microplastics were mainly wrapped and swept by flocs. The density and surface hydrophilicity of microplastics are the main reasons for the discrepancy in their removal efficiency. Calcium alginate also performed well in the removal of microplastics in natural water. When the initial concentration of the polystyrene microplastic suspension was 5 mg/L, the removal rates of microplastics in the five water samples were 99.60% (pipe water), 98.19% (lake water), 98.71% (river water), 100.44% (sludge supernatant), and 100.00% (seawater). Also, flocculation method could almost completely remove fibrous microplastics from washing wastewater. It is aim to provide reference data for the removal of different microplastics in water by flocculation, and also expect to increase the emphasis on microplastic variability in the future removal exploration.

Colonic long-term retention and colonization of probiotics by double-layer chitosan/tannic acid coating and microsphere embedding for treatment of ulcerative colitis and radiation enteritis

Oral probiotics can alleviate enteric inflammations but their rapid transit through the gut limits their retention and colonization in the colon. Here, a novel strategy integrating the bacterial double-layer coating and hydrogel microsphere embedding techniques was used to highly enhance the colonic retention and colonization efficiency of Lactobacillus rhamnosus GG (LGG). LGG was coated by the double layers of chitosan (CS) and tannic acid (TA), and then embedded in calcium alginate (CA) hydrogel microspheres to form LGG@CT@CA. The microspheres resisted gastric liquids, improving LGG safe transit through the stomach to reach the colon. LGG@CT was rapidly released in the colon due to the good swelling of hydrogel microspheres. More importantly, LGG exhibited long-term retention up to 7 days in the colon and colonized the deep site of the colonic mucosa. LGG@CT@CA had a high therapeutic efficiency of ulcer colitis with the long colon and the low intestinal permeability of colonic tissues. LGG@CT@CA also alleviated the small intestinal damage induced by irradiation and the survival rates were improved. The mechanisms included local ROS decrease, IL-10 increase, and ferroptosis reduction in the small intestine. The oral colon-targeted system holds promise for oral probiotic therapy by the long-term retention and colonization in the colon.

Nanoarchitectonics with self-healing hydrogel for hierarchical porous carbons and its application in cadmium-arsenic complex pollution

A cheap and green method for porous carbons (CAC-1) with high surface area (409.41 mg/g) is constructed benefiting from self-healing properties of calcium alginate hydrogel under atmospheric drying. Layered double hydroxides modified CAC-1 (CAC-LDH-1) is applied in cadmium-arsenic complex pollution. The adsorption capacities of the CAC-LDH-1 on Cd(II) and As(V) are 331.03 mg/g and 33.48 mg/g in single system, and 79.87 mg/g and 150.59 mg/g in binary system. In binary system, the synergistic action of Cd(II) ions greatly improve the adsorption capacity and adsorption rate of As(V) ions. The adsorption process of cadmium-arsenic by CAC-LDH-1 mainly follows the second-order kinetic model and Freundlich model, and the adsorption process is endothermic and spontaneous. XPS, FTIR, XRD, SEM-EDS mapping and pore size distribution are carried out to explore the structure and adsorption mechanism of CAC-LDH-1. After treatment with 1 % CAC-LDH-1 for 30 days, the proportions of E1-Cd, F1-As, and F2-As that can be utilized by plants decrease from 46.32 % to 33.15 %, 10.08–2.15 %, and 43.06–35.23 %. Compared with CK group, Cd/As contents in the above/under-ground part of red cherry radish seedlings decrease by 31.41∼59.09 %. CAC-LDH-1 inhibits little effect on the microbial diversity of soil, but change the dominant bacterial colonies.

Desalination of dye and protein by Ba2+/Ca2+ co-crosslinked alginate filtration membrane loaded on polypropylene non-woven

Calcium alginate hydrogel filtration membranes show excellent fouling resistance, but the poor mechanical properties and instability limit the use of the membranes. In this paper, sodium alginate was co-crosslinked with Ba2+ and Ca2+ to prepare barium alginate/calcium alginate composite hydrogel membrane loaded on polypropylene non-woven (Ba/CaAlg-PP). The morphology, structure, and swelling rate of the composite filtration membrane were characterized. The fracture strength of the Ba/CaAlg membrane reached a maximum value of 2.47 MPa. The rejection rates of Ba/CaAlg-PP membrane for Methyl blue and NaCl were close to 100 % and <8.0 %, respectively. Meanwhile, the flux of the Ba/CaAlg-PP membrane in dye/NaCl mixture was 43.2 L·m−2·h−1 and the selectivity coefficient of dye/NaCl reached 154.6. Ba/CaAlg-PP membranes exhibited excellent permeability, rejection and long-term stability in protein desalination. The results of simultaneous fluorescence spectroscopy and molecular dynamics simulations showed that the Ba2+ in the Ba/CaAlg-PP membrane did not disrupt the helical structure of BSA. The Ba/CaAlg-PP membrane has a wide range of applications prospect in proteins and dyes desalination.

Crack-healing and rheological properties of high content fly ash/slag/silica fume green and sustainable cement-based materials incorporating crystalline admixture and calcium alginate biomass hydrogel

Cracking is an important factor affecting the durability of concrete. Rheological properties are important performance indicators of the workability of fresh concrete. Ion chelator (CA) is one kind of crystalline admixture, which can enhance crack-healing of concrete by promoting the formation of calcium carbonate in wet environment. Calcium alginate hydrogel (CaAlg) can maintain the humidity of cementitious matrix and promote the crystallization of inorganic minerals. Therefore, in this study, CaAlg bead was prepared to further improve the crack-healing of cementitious materials containing CA. Self-healing performance was evaluated by visual crack closure and water permeability test. Rheological property was measured by rotor rheometer. Healing mechanism of cementitious materials with CA and CaAlg was analyzed. Results showed that with the increase of CaAlg dosage, yield stress and plastic viscosity of paste decreased gradually. Meanwhile, fly ash and slag reduced viscosity of pastes, while silica fume increased the viscosity of pastes. CA could evidently improve the permeability and mechanical properties of mortar, especially for slag mortar. Self-healing performance test and characterization showed that CaAlg could further enhance crack-healing process of mortar with CA, especially for pure cement and slag mortar. Microscopic testing indicates that CaAlg could induce the formation of vaterite and calcite on its surface to further improve crack-healing efficiency.

Field evaluations of biodegradable boric acid hydrogel baits for the control of Argentine ants: Promising results in vineyards and citrus orchards

Argentine ants are a major pest in California. In this study, a biodegradable calcium alginate hydrogel with an aqueous boric acid bait was tested against Argentine ant populations in a citrus orchard and a vineyard. A new continuous method was developed to produce large quantities of hydrogel bait for the field test. Foraging activity levels of ants were compared between baited and untreated zones. For both study sites, four to five monthly bait applications throughout summer provided a greater than 80% reduction in ant activity. Based on spatial analyses by distance indices, the baited areas were characterized by gaps (areas with lower ant counts) and the untreated control zones were characterized by patches (areas with higher ant counts). This indicated area-wide suppression of Argentine ants. For the citrus orchard, post-baiting panel trap monitoring showed reductions of both ants and Asian citrus psyllid in the baited zone compared to the control. For the vineyard, mid-season soil analyses indicated that the impact of boric acid baiting on soil boron concentration was negligible. In sum, the calcium alginate hydrogel bait with boric acid as an active ingredient may provide a promising solution for Argentine ant baiting.

Visible-light-driven calcium alginate hydrogel encapsulating BiOBr0.75I0.25 for efficient removal of oxytetracycline from wastewater

Oxytetracycline (OTC), a widely used antibiotic, poses significant environmental risks due to its persistence in ecosystems. This study introduces a visible-light-driven photocatalytic hydrogel system for effectively removing OTC from wastewater. The system employs calcium alginate (CA) hydrogel beads encapsulating a BiOBr0.75I0.25 solid solution, which utilizes the synergistic effects of adsorption and visible-light-driven photocatalysis. The BiOBr0.75I0.25 solid solution photocatalyst was synthesized via a solvothermal method, while CA hydrogel beads encapsulating BiOBr0.75I0.25 were prepared through ionic gelation of sodium alginate with calcium chloride. The novel hydrogel, CA-BiOBr0.75I0.25, demonstrated rapid adsorption, capturing over 50 % of OTC within 30 min and achieving a 90.92 % degradation rate within 60 min under visible light. This performance is associated with the unique petal-like structure of BiOBr0.75I0.25 and the high surface area of the hydrogel, facilitating efficient charge separation and radical generation critical for photocatalytic activity. Additionally, the system showed excellent stability and reusability, maintaining an 83 % removal efficiency after five cycles. These findings highlight the potential of this novel hydrogel as a sustainable solution for advanced wastewater treatment technologies.

Study on Adsorption of Cd in Solution and Soil by Modified Biochar-Calcium Alginate Hydrogel.

Contamination with cadmium (Cd) is a prominent issue in agricultural non-point source pollution in China. With the deposition and activation of numerous Cd metal elements in farmland, the problem of excessive pollution of agricultural produce can no longer be disregarded. Considering the issue of Cd pollution in farmland, this study proposes the utilization of cross-linked modified biochar (prepared from pine wood) and calcium alginate hydrogels to fabricate a composite material which is called MB-CA for short. The aim is to investigate the adsorption and passivation mechanism of soil Cd by this innovative composite. The MB-CA exhibits a higher heavy metal adsorption capacity compared to traditional biochar and hydrogel due to its increased oxygen-containing functional groups and heavy metal adsorption sites. In the Cd solution adsorption experiment, the highest Cd2+ removal rate reached 85.48%. In addition, it was found that the material also has an excellent pH improvement effect. Through the adsorption kinetics experiment and the soil culture experiments, it was determined that MB-CA adheres to the quasi-second-order kinetic model and is capable of adsorbing 35.94% of Cd2+ in soil. This study validates the efficacy of MB-CA in the adsorption and passivation of Cd in soil, offering a novel approach for managing Cd-contaminated cultivated land.

Synthesis of calcium alginate hydrogel loaded with platelet rich plasma for use in regenerative medicine and morphological investigation using field emission scanning electron microscope

Synthesis of calcium alginate hydrogel loaded with platelet rich plasma for use in regenerative medicine and morphological investigation using field emission scanning electron microscope

Oral quercetin nanoparticles in hydrogel microspheres alleviate high-altitude sleep disturbance based on the gut-brain axis

High-altitude sleep disturbance is a common symptom of acute mountain sickness, which can be alleviated via modulation of the gut-brain axis. Quercetin (Que) is used to modulate gut microbiota and serves as a potential drug to regulate the gut-brain axis, but the poor solubility and bioavailability affect its biological functions. Here, Que nanoparticles (QNPs) were prepared with zein using an antisolvent method, and QNP-loaded calcium alginate hydrogel microspheres (QNP@HMs) were prepared using electrospinning technology to improve the gastrointestinal stability and intestinal adhesion of QNPs. In the mouse model of high-altitude sleep disturbance, oral administration of QNP@HMs before the mice entering high altitude prolonged sleep duration, improved blood cell recovery, spontaneous behavior and short-term memory, and reduced such inflammation factors as TNF-α and iNOS. Moreover, QNP@HMs enhanced the abundance of probiotics in the gut, including Lactobacillus and Lachnospira, and reduced intestinal inflammation. However, in the mice after gut sterilization by long-term oral antibiotics, QNP@HMs showed no therapeutic effect. QNP@HMs are a promising medication for the prevention of high-altitude sleep disturbance based on the gut-brain axis.

Growth of Romaine Lettuce in Eggshell Powder Mixed Alginate Hydrogel in an Aeroponic System for Water Conservation and Vitamin C Biofortification.

Vitamin C is crucial for physical well-being, and its deficiency can lead to severe health consequences. Biofortification has been used to address this deficiency by enhancing vitamin C in plants. Additionally, soilless agriculture has been used to conserve and optimize water use in comparison to conventional agriculture. While hydrogels have been shown to improve water conservation and are used for biofortification in crops, their application has only been explored in soil-based and hydroponic farming. The aeroponics system is a plant-growing method that has shown potential for increasing yields and biomass while conserving water and nutrients. In this paper, we have developed an aeroponic-compatible medium to grow romaine lettuce (Lactuca sativa L.) with eggshell powder (ESP) mixed with calcium-alginate hydrogel as a substrate and nutrient source aiming to conserve water and incorporate vitamin C through biofortification. Herein, lower water spray time and higher intervals, with varied gel types and ESP concentrations, resulted in healthy lettuce growth. Plants treated with 0.5% ascorbic acid-absorbed ESP-mixed alginate hydrogel for biofortification showed higher levels of vitamin C compared to the traditional method. This study suggests using an alginate hydrogel-ESP-based substrate in aeroponics to reduce water usage and enhance plant biofortification of vitamin C.

Hydroxyapatite-loaded macroporous calcium alginate hydrogels: Preparation, characterization, and in vitro evaluation.

Hydrogels from natural polysaccharides are of great interest for tissue engineering. This study aims (1) to prepare hydroxyapatite-loaded macroporous calcium alginate hydrogels by novel one-step technique using internal gelation in water-frozen solutions; (2) to evaluate their physicochemical properties; (3) to estimate their ability to support cell growth and proliferation in vitro. The structure of the hydrogel samples in a swollen state was studied by confocal laser scanning microscopy and was shown to represent a system of interconnected macropores with sizes of tens micron. The swelling behavior of the hydrogels, their mechanical properties (Young's moduli) in function of a hydroxyapatite content (5-30 mass%) were studied. All hydrogel samples loaded with hydroxyapatite were found to support growth and proliferation of mouse fibroblasts (L929) at long-term cultivation for 7 days. The obtained macroporous composite Ca-Alg-HA hydrogels could be promising for tissue engineering.

Immobilization of Coprinus comatus with magnetic alginate hydrogel microsphere for improving the antioxidant activity of fermentation products

Coprinus comatus is an edible mushroom and its fermented product possesses antioxidant activity. In this study, to further enhance the antioxidant activity and improve the reusability of the strain, calcium alginate hydrogel was used as the carrier for embedding and immobilizing Coprinus comatus. The effects of CaCl2 concentration, sodium alginate concentration, microsphere diameter, and the amount of magnetic particle on the antioxidant activity of fermented products were investigated. The results showed that the magnetic immobilized microsphere prepared by 2.50% CaCl2, 2.00% sodium alginate and 0.50% Fe3O4 had the best fermentation antioxidant activity (EC50 was 0.43 ± 0.01 mg/mL) when the diameter was 5 mm, which increased by 24.56% compared to the initial activity. Besides, the microsphere showed strong reusability, the antioxidant activity was still better than the free strain after being used five times. This study not only enhanced the antioxidant activity of Coprinus comatus fermented product through immobilization, but also provided an effective method for microbial fermentation.