Sodium Alginate Solution Research Articles

Synthesis and Exfoliation of Calcium Organophosphonates for Tailoring Rheological Properties of Sodium Alginate Solutions: A Path toward Polysaccharide-Based Bioink.

Layered nanoparticles with surface charge are explored as rheological modifiers for extrudable materials, utilizing their ability to induce electrostatic repulsion and create a house-of-cards structure. These nanoparticles provide mechanical support to the polymer matrix, resulting in increased viscosity and storage modulus. Moreover, their advantageous aspect ratio allows for shear-induced orientation and decreased viscosity during flow. In this work, we present a synthesis and liquid-based exfoliation procedure of phenylphosphonate-phosphate particles with enhanced ability to be intercalated by hydrophilic polymers. These layered nanoparticles are then tested as rheological modifiers of sodium alginate. The effective rheological modification is proved as the viscosity increases from 101 up to 103 Pa·s in steady state. Also, shear-thinning behavior is observed. The resulting nanocomposite hydrogels show potential as an extrudable bioink for 3D printing in tissue engineering and other biomedical applications, with good shape fidelity, nontoxicity, and satisfactory cell viability confirmed through encapsulation and printing of mouse fibroblasts.

Macroscopic Pattern Formation of Alginate Gels in a Two-Dimensional System.

Macroscopic spatial patterns were formed in calcium alginate gels when a drop of a calcium nitrate solution was placed on the center of a sodium alginate solution on a petri dish. These patterns have been classified into two groups. One is multi-concentric rings consisting of alternating cloudy and transparent areas observed around the center of petri dishes. The other is streaks extending to the edge of the petri dish, which are formed to surround the concentric bands between the concentric bands and the petri dish edge. We have attempted to understand the origins of the pattern formations using the properties of phase separation and gelation. The distance between two adjacent concentric rings was roughly proportional to the distance from where the calcium nitrate solution was dropped. The proportional factor p increased exponentially for the inverse of the absolute temperature of the preparation. The p also depended on the concentration of alginate. The pattern characteristics in the concentric pattern agreed with those in the Liesegang pattern. The paths of radial streaks were disturbed at high temperatures. The length of these streaks shortened with increasing alginate concentration. The characteristics of the streaks were similar to those of crack patterns resulting from inhomogeneous shrinkage during drying.

Experimental investigation of various energy-absorbing layer materials and sodium alginate viscosities on the jet formation in laser-induced-forward-transfer (LIFT) bioprinting

Laser-induced-forward-transfer (LIFT) bioprinting technology has been viewed as a regenerative medicine technology because of its high printing quality and good cell viability. To stabilize the jet to achieve high-quality printing, an energy-absorbing layer (EAL) can be introduced. In this study, three materials (graphene, gelatin, and gold) were utilized as the EAL. The effect of each EAL on the jet generation process was investigated. Besides, the effect of graphene EAL thickness was addressed for various experimental conditions. The jet generation process using sodium alginate solutions with different concentrations (1 and 2 wt. %) was also discussed to investigate the effect of viscosity. The time sequence images of the formed jets utilizing three EALs showed that both graphene EAL and gelatin EAL can promote the formation of jet flow. For the gold EAL, no jet flow was observed. This study provides experimental verifications that the interaction between laser and EAL materials can result in different jets due to various dominant interaction mechanisms. For example, strong absorption in the infrared range for the graphene EAL, strong scattering loss for the gelatin EAL, and strong absorption in the ultraviolet range but weak absorption in the infrared for the gold EAL. We also observed the holes left on the EAL after the printing was completed. The thermal effect is dominant to create regular and round shape holes for the graphene EAL, but it changes to the mechanical effect for the gold EAL because of the existence of irregular and unorganized holes. In addition, we identified the existence of an input laser energy threshold value for a certain thickness graphene EAL. More laser energy is required to break down thicker graphene EALs, which will result in a higher initial jet velocity. Furthermore, we explored the effect of sodium alginate (SA) solution's viscosity on the generated jet. We found that a high-viscosity SA solution can result in a low initial jet velocity, a short jet, and small droplets on the receiving substrate. The findings from this study help determine the mechanisms of EAL–laser interaction with different EAL materials in the LIFT process. This work aims to facilitate the development of new EAL and bioink to achieve stable jet formation and high printing quality in future LIFT bioprinting.

Alginate-modulated continuous assembly of iron/tannic acid composites as photothermally responsive wound dressings for hemostasis and drug resistant bacteria eradication

Multifunctional dressing materials are highly required to combat multidrug resistant bacteria in wound infections. Here an alginate-based aerogel dressing is reported that combines photothermal bactericidal activity, hemostatic property, and free radical scavenging for skin wound disinfection and accelerated wound healing. The aerogel dressing is facilely constructed by immersing a clean nail (Fe) in a mixed solution of sodium alginate (Alg) and tannic acid (TA), followed by freezing, solvent replacement, and air drying. The Alg matrix plays an essential role in modulating the continuous assembly process between TA and Fe to allow the homogenous distribution of TA-Fe metal-phenolic networks (MPN) in the resulting composite, without forming aggregates. The photothermally responsive Nail-TA/Alg aerogel dressing is successfully applied in a murine skin wound model infected with Methicillin-resistant Staphylococcus aureus (MRSA). This work provides a facile strategy to integrate MPN with the hydrogel/aerogel matrix through in situ chemistry, which is promising for developing multifunctional biomaterials and biomedicine.

Design, Preparation, and Physicochemical Characterisation of Alginate-Based Honey-Loaded Topical Formulations.

Honey has widespread use as a nutritional supplement and flavouring agent. Its diverse bioactivities, including antioxidant, antimicrobial, antidiabetic, anti-inflammatory, and anticancer properties, have also made it an aspirant natural product for therapeutic applications. Honey is highly viscous and very sticky, and its acceptance as a medicinal product will require formulation into products that are not only effective but also convenient for consumers to use. This study presents the design, preparation, and physicochemical characterisation of three types of alginate-based topical formulations incorporating a honey. The honeys applied were from Western Australia, comprising a Jarrah honey, two types of Manuka honeys, and a Coastal Peppermint honey. A New Zealand Manuka honey served as comparator honey. The three formulations were a pre-gel solution consisting of 2-3% (w/v) sodium alginate solution with 70% (w/v) honey, as well as a wet sheet and a dry sheet. The latter two formulations were obtained by further processing the respective pre-gel solutions. Physical properties of the different honey-loaded pre-gel solutions (i.e., pH, colour profile, moisture content, spreadability, and viscosity), wet sheets (i.e., dimension, morphology, and tensile strength) and dry sheets (i.e., dimension, morphology, tensile strength, and swelling index) were determined. High-Performance Thin-Layer Chromatography was applied to analyse selected non-sugar honey constituents to assess the impacts of formulation on the honey chemical composition. This study demonstrates that, irrespective of the honey type utilised, the developed manufacturing techniques yielded topical formulations with high honey content while preserving the integrity of the honey constituents. A storage stability study was conducted on formulations containing the WA Jarrah or Manuka 2 honey. The samples, appropriately packaged and stored over 6 months at 5, 30, and 40 °C, were shown to retain all physical characteristics with no loss of integrity of the monitored honey constituents.

Versatile magnetic hydrogel soft capsule microrobots for targeted delivery

Maintaining the completeness of cargo and achieving on-demand cargo release during long navigations in complex environments of the internal human body is crucial. Herein, we report a novel design of magnetic hydrogel soft capsule microrobots, which can be physically disintegrated to release microrobot swarms and diverse cargoes with almost no loss. CaCl2 solution and magnetic powders are utilized to produce suspension droplets, which are put into sodium alginate solution to generate magnetic hydrogel membranes for enclosing microrobot swarms and cargos. Low-density rotating magnetic fields drive the microrobots. Strong gradient magnetic fields break the mechanical structure of the hydrogel shell to implement on-demand release. Under the guidance of ultrasound imaging, the microrobot is remotely controlled in acidic or alkaline environments, similar to those in the human digestion system. The proposed capsule microrobots provide a promising solution for targeted cargo delivery in the internal human body.

Sustainable, Insoluble, and Photonic Cellulose Nanocrystal Patches for Calcium Ion Sensing in Sweat.

Self-assembly of cellulose nanocrystals (CNCs) is invaluable for the development of sustainable optics and photonics. However, the functional failure of CNC-derived materials in humid or liquid environments inevitably impairs their development in biomedicine, membrane separation, environmental monitoring, and wearable devices. Here, a facile and robust method to fabricate insoluble hydrogels in a self-assembled CNC-polyvinyl alcohol (PVA) system is reported. Due to the reconstruction of inter- or intra-molecular hydrogen bond interactions, thermal dehydration makes an optimized CNC/PVA photonic film form a stable hydrogel network in an aqueous solution rather than dissolve. Notably, the resulting hydrogel exhibits superb mechanical performance (stress up to 3.3 Mpa and tough up to 0.73MJm-3 ) and reversible conversion between dry and wet states, enabling it convenient for specific functionalization. Sodium alginate (SA) can be adsorbed into the CNC photonic structure by swelling dry CNC/PVA film in a SA solution. The prepared hydrogel showcases the comprehensive properties of freezing resistance (-20°C), strong adhesion, satisfactory biocompatibility, and highly sensitive and selective Ca2+ sensing. The material could act as a portable wearable patch on the skin for the continuous analysis of calcium trends during different physical exercises, facilitating their development in precision nutrition and health monitoring.

Osteogenesis Enhancement with 3D Printed Gene-Activated Sodium Alginate Scaffolds.

Natural and synthetic hydrogel scaffolds containing bioactive components are increasingly used in solving various tissue engineering problems. The encapsulation of DNA-encoding osteogenic growth factors with transfecting agents (e.g., polyplexes) into such scaffold structures is one of the promising approaches to delivering the corresponding genes to the area of the bone defect to be replaced, providing the prolonged expression of the required proteins. Herein, a comparative assessment of both in vitro and in vivo osteogenic properties of 3D printed sodium alginate (SA) hydrogel scaffolds impregnated with model EGFP and therapeutic BMP-2 plasmids was demonstrated for the first time. The expression levels of mesenchymal stem cell (MSC) osteogenic differentiation markers Runx2, Alpl, and Bglap were evaluated by real-time PCR. Osteogenesis in vivo was studied on a model of a critical-sized cranial defect in Wistar rats using micro-CT and histomorphology. The incorporation of polyplexes comprising pEGFP and pBMP-2 plasmids into the SA solution followed by 3D cryoprinting does not affect their transfecting ability compared to the initial compounds. Histomorphometry and micro-CT analysis 8 weeks after scaffold implantation manifested a significant (up to 46%) increase in new bone volume formation for the SA/pBMP-2 scaffolds compared to the SA/pEGFP ones.

Mosquito repellent microcapsules of nepeta essential oil were prepared by electro‐atomization complex coacervation

AbstractMicrocapsules containing nepeta essential oil (NEO) are prepared by electro‐atomization complex coacervation with sodium alginate and gelatin as wall materials. The effects of conditions such as sodium alginate solution concentration, core‐to‐wall ratio and emulsifier content on the release of essential oil and mosquito repellent properties of the microcapsules are studied. The microcapsules prepared under optimal preparation conditions have good performance and morphology, the encapsulation efficiency and loading capacity being 86.65% and 13.93%, respectively. The prepared microcapsules have adequate morphological characteristics observed using scanning electron microscopy. Fourier transform infrared spectra and thermogravimetric analysis show that NEO is successfully loaded in the microcapsules, and the thermal stability of NEO is improved. In addition, the results of release and repellent tests show that the NEO in the microcapsules could achieve stable release within 15 days and maintain an avoidance rate above 80% within 48 h, indicating the potential application of the microcapsules in the field of mosquito repellents. © 2023 Society of Industrial Chemistry.

In Situ Sprayed Difunctional Gel Avoiding Microenvironments Limitations to Treat Pressure Ulcers.

How to avoid the microenvironment limitations in the therapeutic process of pressure ulcers is still challenging. The development of a functional gel can kill bacteria and scavenge reactive oxygen species (ROS), which is urgently required in the therapeutic process of pressure ulcers. Herein, an in situ sprayed gel is developed with silver nanoparticles (AgNPs) and polydopamine (PDA) NPs (APG) to obviate microenvironment restrictions in treating pressure ulcers. The gel is constructed by spraying sodium alginate solution and CaCl2 solution. AgNPs serve as an antibacterial agent in the formed gel, which can effectively cause bacterial inactivation and show more than 5 log (>99.999%) bacterial killing efficiency against methicillin-resistant S. aureus (MRSA), Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli) in vitro. Meanwhile, PDA NPs serve as the antioxidative agent in the formed gel, which can facilitate the elimination of ROS to address the high ROS problem in wound microenvironment. Based on these features, it is demonstrated through cell and animal experiments that the AgNPs and PDA NPs incorporated gel can realize the effective treatment of MRSA-infected and hydrogen peroxide (H2 O2 )-sensitized pressure ulcers. It is believed that the designed system by a simple spray-coating approach can provide a new therapeutic strategy in biomedical areas.

Micropropagation of Pterocarpus marsupium Roxb. through synthetic seeds and its novel antibiofilm activities against ESKAPE pathogens

Pterocarpus marsupium, an endangered medicinal tree, desists long distance transportation of its recalcitrant propagules, eclipsing the mass vegetative propagation and hindering the pharmaceutical application. Therefore, the present study attempted to develop synthetic seeds by encapsulating the nodal segments using sodium alginate and calcium chloride solutions. A concentration of 100 mM calcium chloride and 3 % sodium alginate proved optimum for preparing uniform synthetic seeds. The highest 76.7 % conversion response of synthetic seed into 8.16 shoots with mean shoot length (4.35 cm) was obtained on Murashige and Skoog (MS) medium containing meta-topolin (5.0 µM) and α-naphthalene acetic acid (1.0 µM) after 12 weeks of culture. However, the shoots failed to induce a rooting response on the aforementioned optimized medium. Therefore, a two-step in vitro rooting procedure was developed. Synthetic seeds of this plant retained their germination potential after storage at 4 ᵒC for eight weeks. Analysis of glutathione-S-transferase (GST) activity indicated that the in vitro culture of synthetic seed on the above medium experienced the lowest physiological stress. The regenerated plantlets were successfully acclimatized to the natural environment, where they showed more than a 90 % survival rate after three months. The heartwood aqueous extract of the tree displayed novel antibiofilm activities against multi-drug resistant ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobcter spp.) pathogens. This study facilitates the multiplication, conservation, and production of novel bioactive compounds.

Development of air-assisted atomization device for the delivery of cells in viscous biological ink prepared with sodium alginate

Skin wounds, especially large-area skin trauma, would bring great pain and even fatal risk to patients. In recent years, local autologous cell transplantation has shown great potential for wound healing and re-epithelialization. However, when the cell suspension prepared with normal saline is delivered to the wound, due to its low viscosity, it is easy to form big drops in the deposition and lose them from the wound bed, resulting in cell loss and uneven coverage. Here, we developed a novel air-assisted atomization device (AAAD). Under proper atomization parameters, 1% (w/v) sodium alginate (SA) solution carrier could be sprayed uniformly. Compared with normal saline, the run-off of the SA on the surface of porcine skin was greatly reduced. In theory, the spray height of AAAD could be set to achieve the adjustment of a large spray area of 1–12 cm2. In the measurement of droplet velocity and HaCaT cell viability, the spray height of AAAD would affect the droplet settling velocity and then the cell delivery survival rate (CSR). Compared with the spray height of 50 mm, the CSR of 100 mm was significantly higher and could reach 91.09% ± 1.82% (92.82% ± 2.15% in control). For bio-ink prepared with 1% (w/v) SA, the viability remained the same during the 72-h incubation. Overall, the novel AAAD uniformly atomized bio-ink with high viscosity and maintained the viability and proliferation rate during the delivery of living cells. Therefore, AAAD has great potential in cell transplantation therapy, especially for large-area or irregular skin wounds.

Food encapsulation plant

This article shows an installation for encapsulating food products. Ensuring food security, the constant satisfaction of the population's needs for basic foodstuffs, is one of the main directions of ensuring the national security of any state. There is still an open question of obtaining high-quality capsules with properties and characteristics that dissolve in the desired environment, retain the therapeutic effect and at the same time meet the requirements of the consumer (ease of use, efficiency, reasonable cost). An installation for producing microcapsules was made of such parts: they are Mercury ATX Switching Power Supply-450W power supply; aquarium tube; glass washer pump; variable resistor with 10K switch; DC-dc DC voltage stabilizer, LM2596S module; gelatin, sodium alginate solution; electromagnetic mixer; plastic sprayer for spraying water (nozzle); calcium chloride solution. There are many technologies of the encapsulation process. Capsules can be obtained by drip, disk spraying methods. In this work, sodium alginate and gelatin were selected as the encapsulating material. A gelatin solution with the addition of sodium alginate was used as an aqueous solution of the gel-forming mixture. The best option is the composition of capsules containing 0.5% alginate and gelatin, the solution should be used at a temperature of 40° C. Capsules were obtained by the drip method. Capsules obtained from 0.5% sodium alginate were soft, with a smooth surface, with an average size of 2,0×10-3м.

Гибридный гель для замены твердых жиров в кондитерских изделиях

The World Health Organization recommends reducing the intake of saturated fatty acids. However, a direct replacement of solid fats with liquid oils affects the technological and consumer properties of food. The research objective was to develop a hybrid gel with a dense structure based on oleogel and hydrogel to replace saturated fats in semi-finished confectionery products.
 The study featured samples of oleogel from sunflower oil and beeswax at a concentration of 10, 15, and 20% and hybrid gels prepared by mixing the oleogel with a 2% aqueous solution of sodium alginate at ratios of 99:1, 95:5, and 90:10. The samples were tested for strength, adhesive power, viscosity index, consistency, and Young modulus using a TA-XT Plus texture analyzer (Stable Micro Systems Ltd., UK). The water activity was studied using a water activity analyzer LabMaster (Novasina, Lab Master, Switzerland).
 The oleogel samples with wax concentrations of 20 and 15% demonstrated good adhesive strength. The best hybrid gel was the oleogel with 20% wax at the ratio of 95:5 to hydrogel. This ratio resulted in a considerable gel strength (≤ 408.222) while maintaining a dense and uniform texture (Young modulus ≤ 17.05) for a long time. The oleogels had low moisture content (Aw = 0.6 ± 0). The shelf life at 4–10°C was 6 months. The samples had good sensory properties, i.e., clear taste and smell, strong uniform structure and consistency, etc. The paper introduces a formulation for a semi-finished confectionery product with a hybrid gel instead of 30% cocoa butter substitute.
 Hybrid gels can be recommended as a substitute for cocoa butter or confectionery fats to reduce the amount of saturated and trans fatty acids. Such a replacement improves the consumer properties of semi-finished and finished products.

Extraction of dietary fiber and phytochemicals from bottle gourd seeds (Lagenaria siceraria), its physicochemical properties and application in food model

This research aimed to extract dietary fiber and phytochemicals from matured bottle gourd (Lagenaria siceraria) seeds and use as ingredients in the preparation of cookies. Extraction of dietary fiber was performed using alkaline (AEDF), enzymatic (EEDF), and ultrasound-assisted alkali extraction (UAE). UAE gives a higher yield of 75.81% dietary fiber where the optimized conditions are solute: solvent; 1: 23.90 mg/ml, time; 27.20 min and amplitude; 47.76%. Comparison of physicochemical and functional properties of extracted dietary fiber was done and ultrasound-assisted alkaline extracted dietary fiber (UDF) was found to be the best. Extraction of phytochemicals using ultrasound-assisted alkaline extraction under the condition of 70% amplitude, 45 °C temperature, and duration of 15 min, and identification was done using RP-HPLC analysis and encapsulated using sodium alginate solution (2%) as the wall material. Fiber enriched cookies were developed by incorporating the extracted dietary fiber (3, 6, 9, 12 and 15%) and encapsulated phytochemicals beads (1, 1.5, 2, 2.5 and 3%) in 5 different formulations. The result of this study revealed that matured bottle gourd seeds can serve as a potential, inexpensive dietary fiber source and phytochemicals, which can further be used to develop functional foods.

Improved pervaporation dehydration performance of alginate composite membranes by embedding organo-montmorillonite

In this work, two different montmorillonite (MMT) nanoclays were incorporated in sodium alginate (Alg) solution for fabrication of hybrid membrane for pervaporative separation of aqueous isopropanol solution. Sodium-MMT (Na-MMT) was modified to organo-montmorillonite (O-MMT) using cationic surfactant dialkyldimethyl ammonium chloride (DDAC). The influence of incorporating MMTs on the membrane properties and separation performance was investigated. Intercalating of DDA+ on Na-MMT tailored the chemical structure and morphology of the MMTs. Integrating of MMTs modified the physicochemical properties of the membranes. The membrane morphology shows the homogeneous dispersion of MMTs in athe Alg matrix. Positron annihilation lifetime spectroscopy analysis revealed a tuned microstructure of the membranes. Swelling measurements showed better compatibility of O-MMT than the Na-MMT with the Alg matrix. As a result, AlgO-MMT had better separation performance than the AlgNa-MMT with permeation flux of 4764 g∙m−2∙h−1 and water concentration in permeate of 99.99 wt% on dehydrating 70 wt% IPA/water aqueous solution at 25 °C. Owing to the favorable compatibility between the polymer and filler, AlgO-MMT membrane demonstrated stability at different pervaporation operating conditions and long-term use. Our results demonstrated that the properties and separation performance of Alg membrane can be enhanced through incorporation of O-MMTs.

Probiotic Lactobacillus paragasseri K7 Nanofiber Encapsulation Using Nozzle-Free Electrospinning.

Probiotics are live microorganisms that can have beneficial effects on humans. Encapsulation offers them a better chance of survival. Therefore, nozzle-free electrospinning was introduced for their embedding in nanofibrous material. Probiotic Lactobacillus paragasseri K7 in lyophilized and fresh form, with and without inulin as prebiotic, was added to a polymer solution of sodium alginate (NaAlg) and polyethylene oxide (PEO). Conductivity, viscosity, pH, and surface tension were determined to define the optimal concentration and volume ratio for smooth electrospinning. The success of the formed nanoscale materials was examined by scanning electron microscope (SEM), while the entrapment of probiotics in the nanofibrous mats was detected by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Spontaneous diffusion of bacteria from electrospun samples in PBS buffer pH 7.4 was studied by plate counting on MRS agar. By exposing polymer solutions containing L. paragasseri K7 and inulin to a high electric field, the nanofilm was formed on a polypropylene substrate, used as collecting material. When polymer solutions without inulin were used, the bead-like nanofibers may have become visible. The SEM results suggest that inulin, in addition to K7 strain, additionally lowers the conductivity of spinning macromolecular solution and hinders the nanofiber formation. The results of ATR-FTIR confirmed the presence of L. paragasseri K7 embedded in nanocomposites by the appearance of characteristic peaks. The samples containing the probiotic regardless of its form with inulin had similar surface composition, except that the sodium content was higher in the samples with fresh probiotic, probably due to greater and thus less easy embedding of the bacteria in NaAlg. Within 2 h, the largest amount of probiotic strain K7 was spontaneously released from the electrospun sample containing the inulin and probiotic in freeze-dried form (44%), while the amount released from the nanofibrous sample, which also contained the inulin and probiotic in fresh form, was significantly lower (21%). These preliminary results demonstrate the potential of nozzle-free electrospinning technology for the development of probiotic delivery systems for short-term use, such as feminine hygiene materials (tampons, pads, napkins).

Preparation and evaluation of a novel alginate-arginine-zinc ion hydrogel film for skin wound healing

In this paper, the mixed solution of sodium alginate (SA) and arginine (Arg) was dried into a film and then crosslinked with zinc ion to form sodium alginate-arginine-zinc ion (SA-Arg-Zn2+) hydrogel for skin wound dressings. SA-Arg-Zn2+ hydrogel had higher swelling ability, which was beneficial to absorbing wound exudate. Moreover, it exhibited antioxidant activity and strong inhibition against E. coli and S. aureus, and had no obvious cytotoxicity to NIH 3T3 fibroblasts. Compared with other dressings utilized in rat skin wound, SA-Arg-Zn2+ hydrogel showed better wound healing efficacy and the wound closure ratio reached to 100 % on the 14th day. The result of Elisa test indicated that SA-Arg-Zn2+ hydrogel down-regulated the expression of inflammatory factors (TNF-α and IL-6) and promoted the growth factor levels (VEGF and TGF-β1). Furthermore, H&E staining results confirmed that SA-Arg-Zn2+ hydrogel could reduce wound inflammation and accelerate re-epithelialization, angiogenesis and wound healing. Therefore, SA-Arg-Zn2+ hydrogel is an effective and innovative wound dressing, moreover, the preparation technique is simple and feasible for industrial application.

Investigating the performance of surface-engineered membranes for direct contact membrane distillation

ABSTRACT Direct contact membrane distillation (DCMD) is an emerging technology gaining attraction in seawater desalination and concentration of aqueous solutions. In this study, a facile surface modification strategy using hydrophobic ZIF-8 and a fluoroalkylsilane (FAS) was employed to improve the performance of commercial PVDF and PVDF/PTFE blend membranes. The PVDF/PTFE membrane modified using 10 wt./vol % hydrophobic ZIF-8 and 1 H, 1 H, 2 H, 2 H-perfluorooctyltriethoxysilane (PFOTES) exhibited the highest water contact angle (121 ± 4.7°), improved surface roughness (51.6 ± 1.4 nm), most significant vapor flux (17.6 ± 2 L/m2h), and salt rejection of 99.98% with 10,000 ppm NaCl synthetic feed solution at the optimum operating conditions. The surface-engineered membranes exhibited excellent anti-fouling (360 minutes) and anti-wetting performance (240 minutes) when challenged with saline feed solution containing 50 ppm sodium alginate solution and 0.1 mM sodium dodecyl sulfate, respectively. The surface engineered membranes produced permeate of uniform quality for>10 h and could recover~31% water during actual seawater desalination (10 h). Moreover, these membranes could concentrate propylene glycol by a factor of 1.24 within 6 h and retain>80% of it. This facile surface modification strategy holds an excellent potential to be further explored for commercial applications.

Temporary hydraulic barriers using organic gel for enhanced aquifer remediation during groundwater flushing: Bench-scale experiments

This study presents the use of organic gel-forming material for the construction of hydraulic barriers in aquifer, which can be easily removed after use. Experiments on the performance of the temporary hydraulic barrier during NAPL removal (aquifer flushing) were also conducted. An aqueous solution of sodium alginate was injected into the horizontally oriented, 2-dimensional flow chamber packed with sand, followed by gelation using a calcium solution. The alginate gel formed in the porous media produced a circular shape barrier (24 cm diameter, 1.3 cm thickness) that was successfully removed using sodium bicarbonate solution (1.0 M) in 72 h, whereas the gel was stable for 7 days during simulated groundwater flushing at the same flow rate as the sodium bicarbonate solution. When circular hydraulic barriers (12 cm diameter each, 14 cm apart) were set on either side of the NAPL (n-hexane and PCE mixture)-contaminated zone, the increased water flux during water flushing resulted in significantly increased PCE removal by almost 108%. When a surfactant solution (sodium dodecyl sulfate, 0.037%) was applied, the influenced groundwater flow controlled by hydraulic barriers on the NAPL removal was amplified by 196% removal.