Mixture Of Alginate Research Articles

Weakening of the Transdermal Effect of p-Phenylenediamine Pigments by the Temperature-Sensitive Poloxamer Sodium Alginate Gel

Abstract A temperature-sensitive hair dye was prepared with a poloxamer-sodium alginate mixture. When the hair dye was applied to the hair (< 32 °C), it retained its flow dynamics. The hair dye was able to undergo a phase change and formed a solid as soon as it touched the scalp (32°C), which reduced the transdermal amount of p-phenylenediamine (PPD) and also adverse effects and toxicity. Compared to a conventional hair dye, the temperature-sensitive hair dye achieved a reduction of the transdermal amount of p-phenylenediamine by almost 65% at different concentrations. At the same time, the colouring effect was not significantly reduced. The poloxamer alginate hydrogel can be used as a novel colouring material to reduce the harm of the dye intermediate to the human body when colouring hair.

Effect of Powder/Water Ratio Variation on Viscosity, Tear Strength and Detail Reproduction of Dental Alginate Impression Material (In Vitro and Clinical Study).

Background: Alginate impression is a common dental polymeric material, presented as powder to be mixed with water. Aim: 1. To analyze the effect of alginate powder/water ratio variation on viscosity, tear strength and detail reproduction by in vitro tests, and 2. To evaluate this variation’s effect on patients’ impressions. Materials and methods: Two commercial alginate products were mixed in different viscosities. Viscosity was measured by a viscometer. For the tear strength test, V-shaped specimens were used. For detail reproduction, a die with three scribed lines was used. Clinical dental impressions were examined by stereomicroscope. Results: The alginate specimens mixed with a higher powder/water ratio showed a higher viscosity and tear strength compared to those with a lower powder/water ratio. Both alginate mixtures reproduced two scribed lines in a detail reproduction test. On the other hand, no clear clinical difference was detected when examining dental impressions mixed with a different powder/water ratio. Conclusion: Although increasing the powder/water ratio of mixed alginate raised the resultant viscosity and tear strength by an in vitro test, clinically, no clear difference in tearing was detected. Detail reproduction was minimally affected by the variation in powder/water ratio.

Investigation of the aggregation, clouding and thermodynamics of the mixture of sodium alginate with sodium dodecyl sulfate and triton X-100 in aqueous and aqua-organic mixed solvents media

Herein, the aggregation, phase separation and binding behavior of sodium alginate (SA) and surfactants (anionic (SDS) and nonionic (TX-100)) mixture in aqueous and aqua-organic mixed solvents have been investigated applying the conductivity, cloud point, and UV–visible spectroscopic methods. In the current study, the various physico-chemical parameters (critical micelle concentration (CMC), extent of bound counter ions, cloud point (CP), binding constant (Kb), thermodynamic properties, and transfer parameters) were determined. The addition of SA facilitates SDS micellization. The CMC of the SA + SDS mixtures were obtained to be dependent on SA concentration, composition of mixed solvents, and temperature. The CMC of the SA + SDS mixture were found to be greater in magnitude in aqua-organic (dimethyl formamide (DMF), acetonitrile (AN), ethylene glycol (EG), and 1,4-dioxane (DX)) mixed solvents than the values observed in H2O medium. The values of counterion binding were found to be enhanced with the boost of concentration of SA and other organic additives. The Kb values of SA + TX-100 mixtures were computed from the Benesi-Hildebrand (BH) plot and the Kb values were found to be temperature-dependent. The CP values of the SA + TX-100 mixture experienced a lessening with growing contents of SA and got enhanced in diols (EG/ propanediol (PrD)) media. The negative values of free energy changes dictate that the micellization of SA + SDS mixture and binding processes for the SA + TX-100 mixture are spontaneous in nature while the positive free energy changes indicate the non-spontaneity of clouding phenomena of SA + TX-100 mixture. The obtained values of enthalpy and entropy changes recommend the presence of hydrophobic, electrostatic, and ion–dipole interactions amongst SA and SDS while hydrogen bonding, ion–dipole, and van der Walls forces are the proposed forces between SA and TX-100. Excellent enthalpy–entropy compensation was observed in each case.

Amylase Production by Aspergillus niger immobilized in Microporous Calcium Alginate Gel Beads

Microporous calcium alginate gel beads were investigated as potential solutions to mass transfer limitations in immobilized cultures. The beads were prepared by gelling mixtures of sodium alginate and fillers (starch or granulated sugars) in calcium chloride solution. The resulting beads were cured in the same solution, during which the fillers leached out of the beads thereby creating micro-pores in the beads (microporous beads). The effectiveness of the microporous beads in improving amylase production by Aspergillus niger LC 269109 was investigated. Spores of A. niger were immobilized in the microporous beads and used for batch alpha amylase and gluco amylase production. Amylase production by the A. niger immobilized in the microporous beads were significantly higher (p<0.01) than the values obtained with the conventional calcium alginate gel beads. Under all the conditions investigated, gluco-amylase activities were significantly (p<0.01) higher than the alpha-amylase activities. Under the optimum conditions of inoculum concentration (1.0 × 105 spores/ml), pH (6), temperature (35°C), bead diameter (3 mm) and calcium chloride concentration (1.5%), the gluco-amylase and alpha amylase activities were 11.98 U/ml and 6.7 U/ml respectively, which were significantly higher (p<0.05) than the 7.8 U/ml and 3.2 U/ml obtained with the conventional gel beads.

Paclitaxel-Loaded Folate-Targeted Albumin-Alginate Nanoparticles Crosslinked with Ethylenediamine. Synthesis and In Vitro Characterization.

Among the different ways to reduce the secondary effects of antineoplastic drugs in cancer treatment, the use of nanoparticles has demonstrated good results due to the protection of the drug and the possibility of releasing compounds to a specific therapeutic target. The α-isoform of the folate receptor (FR) is overexpressed on a significant number of human cancers; therefore, folate-targeted crosslinked nanoparticles based on BSA and alginate mixtures and loaded with paclitaxel (PTX) have been prepared to maximize the proven antineoplastic activity of the drug against solid tumors. Nanometric-range-sized particles (169 ± 28 nm–296 ± 57 nm), with negative Z-potential values (between −0.12 ± 0.04 and −94.1± 0.4), were synthesized, and the loaded PTX (2.63 ± 0.19–3.56 ±0.13 µg PTX/mg Np) was sustainably released for 23 and 27 h. Three cell lines (MCF-7, MDA-MB-231 and HeLa) were selected to test the efficacy of the folate-targeted PTX-loaded BSA/ALG nanocarriers. The presence of FR on the cell membrane led to a significantly larger uptake of BSA/ALG–Fol nanoparticles compared with the equivalent nanoparticles without folic acid on their surface. The cell viability results demonstrated a cytocompatibility of unloaded nanoparticle–Fol and a gradual decrease in cell viability after treatment with PTX-loaded nanoparticle–Fol due to the sustainable PTX release.

Water chestnut, rice, corn starches and sodium alginate. A comparative study on the physicochemical, thermal and morphological characteristics of starches after dry heating

Water chestnut (Trapa bispniosa), rice and corn starch were modified with sodium alginate and subjected to dry heating for 0,2 and 4 h for at 130 °C. The physicochemical, thermal and morphological properties of native as well as modified starches were determined. Thermal and morphological properties were studied using Differential Scanning Calorimeter (DSC) and Scanning Electron Microscopy (SEM). It was observed that the dry heating of starches with and without sodium alginate significantly reduce the swelling power, solubility, paste clarity whereas, water absorption and syneresis increased. The swelling power was higher for corn starch as compared to other starches while rice starch has higher syneresis. In the presence of sodium alginate the water absorption was increased in all starch samples upon heating. The onset temperature was found to be increased after dry heating of all starches. The maximum increased was noticed for rice starch. Morphological studies showed the damaging of granule surface with the accumulation of leached amylose and gum but total degradation was not observed. Peak viscosity, final viscosity, breakdown, and setback of RS- sodium alginate mixture were reduced on dry heating. Although pasting temperature of rice starch was not significantly changed.

Biodegradable and antimicrobial CSC films containing cinnamon essential oil for preservation applications

The degradable antibacterial film (CSC) was prepared by overcoating method using chitosan as the outer layer and the mixture of sodium alginate and the amphiphilic starch encapsulated anti-bacterial cinnamon essential oil (CMS-LS-CO) as the intermediate layer, which was used in place of polyethylene film. The surface structural, biodegradability, mechanical, transmittance, antibacterial and preservation properties of the CSC films were investigated, considering the effects of CMS-LS-CO concentration. As the addition of CMS-LS-CO at 0.25, 0.5 and 1 % increased, TS and elongation at break of CSC films decreased and the water vapor permeability had little change. When CMS-LS-CO was added at 0.5 %, CSC films achieved better preservation and mechanical properties, at the same time, the inhibition rates of E. coli and S. aureus were 36 % and 30 %, respectively. The preservation experiment on cherry tomatoes showed that the CSC films exhibited a certain freshness effect, which maintained higher hardness and lower weight loss rate within two weeks than polyethylene films. The nature degradation of the films showed that the soil biodegradability rate reached 70 % in 28 days. Compared to polyethylene films, the degradable CSC films had excellent antimicrobial activity and preservation properties, showing higher potential for fruit preservation applications.

Fabrication of AuNPs into alginate biopolymer and functionalized by thiourea as a film shape probe for palladium(II) sensing

• Au nanoparticles (AuNPs) were in situ synthesized into alginate polysaccharide biopolymer. • The AuNPs entrapped in the alginate networks were functionalized by thiourea and shaped as a film. • Functionalized thiourea AuNPs-alginate biopolymer film was used for palladium(II) detection. • The characteristics of thiourea/AuNPs alginate film was performed by TEM, DLS, EDAX and UV–vis spectrophotometry. A simple process was developed for the fabrication of alginate biopolymer film embedded by thiourea-functionalized AuNPs (thiourea/AuNPs) for palladium(II) detection. A mixture of sodium alginate and HAuCl 4 was prepared as the main matrix and the AuNPs were in situ synthesized in alkali media provided by borax. The AuNPs entrapped in the alginate network were functionalized by thiourea and fabricated as a transparent film. The characteristics of thiourea/AuNPs alginate biopolymer film were investigated by Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDX) and UV–vis spectrophotometry. The UV–vis absorption spectrum showed the maximum wavelength of thiourea/AuNPs was at 530 nm. The effect of various parameters such as pH and thiourea concentration on the sensing of palladium(II) ions was investigated. The prepared alginate biopolymer film showed good stability over the time. The calibration graph was linear in the range of 0.05−2.10 μg mL −1 with a detection limit of 0.038 μg mL −1 . The relative standard deviation (n = 10) for 0.6 and 1.2 μg mL −1 of palladium(II) was 4.6% and 3.5%, respectively. The sensing system was successfully applied for the determination of palladium in walnut leaves, wastewater, dental amalgam, and ceramic capacitor samples.

Microencapsulation of Probiotic <em>Lactobacillus casei </em>based on Alginate and Chitosan Materials

Probiotics are microorganisms that live in the stomach related plot which can give health advantages to the body. Probiotics must be able to survive in an acidic environment (pH = 2) during transit in the gastric to arrive the large intestine in adequate amounts (106 - 107 CFU/g) to allow for colonization and reproducing. However, most of these probiotics cannot survive in adequate amountsin acidic conditions. One way to protect probiotic cells under these conditions is through a microencapsulation system. Microencapsulation is done to protect probiotic cells from low pH, bile salts, etc. Lactobacillus casei includes probiotics that are very sensitive to pH 2-2.5. The non-encapsulated Survivability of L. casei is only 40.14% in liquid pH 2 from 8.75log CFU/g to 3.53log CFU/g while L. casei carried out microencapsulation can achieve survivability of 63.47% to 95.3%. Alginate is a microencapsulation material that is inexpensive and sensitive to changes in pH so that it is suitable as a microencapsulation of probiotics. The surface of porous alginate needs other ingredients that can be requested by the pores. Alginate is resistant to pH 2-2.5 and expands at neutral pH to alkaline, which results in increased alginate pores. Chitosan can be used as an alginate mixture in probiotic microencapsulation materials. Chitosan can bind by crosslinking with alginate, which is between the NH2 group of chitosan and COO- group of alginate.

Synthesis and characterization of magnesium diboride nanosheets in alginate/polyvinyl alcohol scaffolds for bone tissue engineering

Boride, which belongs to the distinct category of ceramic materials, has attracted significant attention in tissue engineering applications. Magnesium diboride (MgB2) consists of a plane of magnesium atoms sandwiched between the layers of boron. Even though MgB2 showed its role in various applications, its effect on osteogenesis has not yet been investigated. In this study, we synthesized MgB2 nanosheets (MgB2NS), a new class of 2D-nanoscale structures, by the ultrasonication exfoliation method and incorporated them into a polymeric mixture of alginate (Alg) and polyvinyl alcohol (PVA) by the freeze-drying procedure. The synthesized scaffolds (Alg/PVA/MgB2NS) were characterized by SEM, XRD, FT-IR, protein adsorption, swelling, degradation, and biomineralization studies. These scaffolds were non-toxic to mouse mesenchymal stem cells (mMSCs). MgB2NS in the scaffolds enhanced osteoblast differentiation of mMSCs at the molecular level by the expression of Runx2 and osteoblast differentiation marker genes and at the cellular level by alkaline phosphatase, alizarin Red and von Kossa staining. Overall, our results showed that MgB2NS in Alg/PVA scaffolds have osteogenic potential, suggesting their possible use in bone tissue engineering applications.

Efficient Entrapment of Carbonic Anhydrase in Alginate Hydrogels Using Liposomes for Continuous-Flow Catalytic Reactions.

A versatile approach to entrap relatively small enzymes in hydrogels allows their diverse biotechnological applications. In the present work, bovine carbonic anhydrase (BCA) was efficiently entrapped in calcium alginate beads with the help of liposomes. A mixture of sodium alginate (3 wt %) and carbonic anhydrase–liposome conjugates (BCALs) was dripped into a Tris-HCl buffer solution (pH = 7.5) containing 0.4 M CaCl2 to induce the gelation and curing of the dispersed alginate-rich droplets. The entrapment efficiency of BCALs, which was defined as the amount of catalysts entrapped in alginate beads relative to that initially charged, was 98.7 ± 0.2% as determined through quantifying BCALs in the filtrate being separated from the beads. When free BCA was employed, on the other hand, a significantly lower entrapment efficiency of 27.2 ± 4.1% was obtained because free BCA could pass through alginate matrices. Because the volume of a cured alginate bead (10 μL) entrapped with BCALs was about 2.5 times smaller than that of an original droplet, BCALs were densely present in the beads to give the concentrations of lipids and BCA of 4.6–8.3 mM and 1.1–1.8 mg/mL, respectively. Alginate beads entrapped with BCALs were used to catalyze the hydrolysis of 1.0 mM p-nitrophenyl acetate (p-NA) at pH = 7.5 using the wells of a microplate or 10 mL glass beakers as batch reactors. Furthermore, the beads were confined in a column for continuous-flow hydrolysis of 1.0 mM p-NA for 1 h at a mean residence time of 8.5 or 4.3 min. The results obtained demonstrate that the conjugation of BCA to liposomes gave an opportunity to achieve efficient and stable entrapment of BCA in alginate hydrogels for applying to catalytic reactions in bioreactors.

Cross-linked arabinoxylan in a Ca2+-alginate matrix reversed the body weight gain of HFD-fed C57BL/6J mice through modulation of the gut microbiome

Here, we compared the effects of different physical forms of arabinoxylan (AX) – a microsphere of cross-linked arabinoxylan (CAX) in a Ca2+-alginate matrix (MC) and physical mixture of AX and alginate (PM) on gut microbiota and development of obesity in C57BL/6J mice. Supplementation of MC in high fat (HF) diet to mice for 10 weeks significantly reversed the body weight gain induced by the HF diet, along with less fat accumulation in both livers and the epididymal adipose than the PM group. Microbiome analysis showed that MC significantly altered the gut microbiota composition with a noticeable increase of butyrogenic bacteria of Lachnospiraceae. The butyrate produced by MC fermentation and the increased abundance of Lachnospiraceae might be the underlying mechanism of the anti-obesity effect of MC. The results indicated that the physical forms of dietary fiber are closely associated with its health benefits, and MC might be served as a new functional food ingredient to prevent obesity.

Novel Ramie Fabric-Based Draping Evaporator for Tunable Water Supply and Highly Efficient Solar Desalination.

Interfacial solar-driven evaporation is a promising path to address the scarcity of freshwater. Lots of efforts have been made to develop highly efficient photothermal materials and optimize operational efficiency. However, the designed solar evaporator tends to directly contact with seawater, leading to inevitable parasitic heat loss and the total suppression of evaporation of the backside. Here, we show a novel draping fabric system by separating the evaporation interface from bulk water. The evaporation area was exposed to air with enhanced natural convection and double-side evaporation. The draping fabric was prepared by coating the mixture of carbon black (CB) and cross-linked sodium alginate (SA) on ramie fabric (CSRF). The draping CSRF realized an evaporation rate of 1.81 kg m-2 h-1 and efficiency of 96.6% under 1 sun illumination (1 kW m-2). In addition, by changing the yarn fineness of the fabric, a tunable water supply can be realized to optimize the energy distribution. This work provides a new strategy to design and optimize the solar evaporation system, exhibiting great potential in real-world applications.

Three-Dimensional Multilayer Vertical Filament Meshes for Enhancing Efficiency in Fog Water Harvesting.

Novel types of vertical filament mesh (VFM) fog harvesters, 3D VFM fog harvesters, and multilayer 3D VFM fog harvesters were developed by mimicking the water-harvesting nature of desert beetles and the spider silks from fog. Four different types of polymer filaments with different hydrophilic–hydrophobic properties were used. The polymer filaments were modified with the polyurethane–sodium alginate (PU–SA) mixture solution, and a simple spraying method was used to form alternating 3D PU–SA microbumps. Polymer VFMs exhibited a higher fog-harvesting efficiency than the vertical metal meshes. Moreover, the hydrophobic VFM was more efficient in fog harvesting than the hydrophilic VFM. Notably, the fog-harvesting efficiency of all VFMs increased by 30–80% after spraying with the mixed PU–SA solution to form a 3D geometric surface structure (3D PU–SA microbumps), which mimicked the desert beetle back surface. This modification caused the fog-harvesting efficiency of PTFE 3D VFM to be thrice higher than that of Fe VFM. This increase was attributed to the improved synergistic effects of fog capturing, droplet growing, and droplet shedding. The multilayer VFMs were more efficient in fog harvesting than the single-layer VFMs because of a larger droplet capture area. The fog-harvesting efficiency of two-layer and four-layer polymer VFMs was approximately 35% and about 45% higher than that of the single-layer polymer VFMs, respectively. The four-layer PTFE 3D VFM with the type B PU–SA bump surface (bump/PU–SA) had the highest efficiency of 287.6 mL/m2/h. Besides the high fog-harvesting efficiency, the proposed polymer VFMs are highly stable, cost-effective, rust-free, and easy to install in practical applications. These advantages are ascribed to the elasticity of the polymer filaments. This work provides new ideas and methods for developing high-performance fog harvesters such as the 3D VFM.

A semi dynamic in vitro digestion study of milk protein concentrate dispersions structured with different polysaccharides

Hydrocolloids are often added as functional ingredients in foods, to better design the structure of the matrix and ensure food quality and optimal sensory properties. However, much less is known about their influence on the physical and chemical changes during gastric digestion. In this study, semi-continuous in vitro gastric digestion was applied on a model food system, prepared with milk protein concentrate (MPC) (3% w/v) and 1% alginate, pectin, guar gum, as well as a 1:1 mixture of alginate and pectin. The dynamics during simulated gastric digestion were observed by measuring particle size distributions, structuring at various length scales, as well as by evaluating differences in protein breakdown. Immediately after contact with the simulated gastric fluids, all samples showed extensive aggregation and formation of different structures. MPC control dispersions (no polysaccharide) and MPC containing alginate formed large inhomogeneous aggregates. The lack of structural homogeneity affected the simulated gastric emptying: there were marked differences in the type of aggregates present at various times of emptying depending on the hydrocolloid present in the mixture. MPC containing pectin or guar gum formed macroscopically homogeneous dispersion, with rather small protein aggregates showing a large population of particles between 60 and 100 ​μm of diameter, with marked differences in microstructure. Pectin created large coacervates, while guar microscopic phase separated systems. These dispersions showed a higher extent of protein digestion, due to the larger surface area created for enzyme activity compared to the macroscopically phase separated matrices. In all cases, there was a large undigested fraction at the end point of 140 ​min. SDS PAGE demonstrated differences in the casein peptides distribution depending on the type of polysaccharide present during simulated gastric emptying. This in spite of similarities in cumulative protein emptied. It was concluded that in this semi-continuous in vitro gastric digestion model, structuring with polysaccharides has a significant impact on gastric emptying and protein digestion kinetics.

Encapsulation in alginate-polymers improves stability and allows controlled release of the UFV-AREG1 bacteriophage

The bacteriophage UFV-AREG1 was used as a model organism to evaluate the encapsulation via extrusion using different hydrocolloids. Pure alginate [0.75%, 1.0%, 1.5% and 2.0% (m/v)] and mixtures of alginate [0.75% or 1.0% (m/v)] with carrageenan [1.25% (m/v)], chitosan [0.5% (m/v)], or whey protein [1.5% (m/v)] were used to produce bacteriophage-loaded beads. The encapsulating solutions presented flow behavior of non-Newtonian pseudoplastic fluids and the concentration of hydrocolloid did not influence (p > 0.05) the morphology of the beads, except for alginate-chitosan solutions, which presented the higher flow consistency index (K) and the lower flow behavior index (n). The encapsulation efficiency was about 99% and the confocal photomicrography of the encapsulated bacteriophages labeled with fluorescein isothiocyanate showed homogenous distribution of the viral particles within the beads. The phages remained viable in the beads of alginate-whey protein even when submitted to pH 2.5 for 2 h. Beads incubated directly in simulated intestinal fluid (pH 6.8) resulted in a minimal of 50% release of the UFV-AREG1 phages after 5 min, even when previously submitted to the simulated gastric fluid (pH 2.5). Encapsulation enabled phages to remain viable under refrigeration for five months. Encapsulated UFV-AREG1 phages were sensitive to dehydration, suggesting the need for protective agents. In this study, for the first-time bacteriophages were encapsulated in alginate-carrageenan beads, as well as alginate-chitosan as a bead-forming hydrocolloid. In addition, a novel procedure for encapsulating bacteriophages in alginate-whey protein was proposed. The assembled system showed efficiency in the encapsulation of UFV-AREG1 bacteriophages using different hydrocolloids and has potential to be used for the entrapment of a variety of bioactive compounds.

Physical appearance and arsenate removal efficiency of Fe(III)-modified clinoptilolite beads affected by alginate-wet-granulation process parameters

Fe(III)-modified clinoptilolite (Fe-Clin) was encapsulated into beads using sodium alginate (NaAlg) and Ca2+ and/or Fe3+ ions by a simple wet-gelation method to obtain Fe-Clin beads. The impacts of various parameters including mixture pH, type of cross-linker, concentration of cross-linking solution and initial mass ratio of NaAlg to Fe-Clin were investigated on the appearance of beads and also their performance in As(V) removal. To increase the net negative surface charge of alginate, pH value of the mixture was essentially adjusted to the level 12–13. This strong alkaline condition increased the ability of alginate mixture to form stable and well-shaped beads. Ca2+ acting as a cross-linker showed a less impact on the beads shape than Fe3+ due to the strong tendency of Fe3+ ions to react with oxygen atoms in carboxylate groups of alginate. A loosely cross-linked Ca2+-alginate network formed during preparation of Fe-Clin beads was considered as the main reason for their lower arsenate removal efficiency of 29.4% rather than 60.5% for those cross-linked in FeCl3. In addition, there were found optimal values of FeCl3 cross-linking solution concentration and initial mass ratio of NaAlg: Fe-Clin as 2% (w/v) and 1:4, respectively to achieve the maximum As(V) removal efficiency of 82%.

Characterization of Biodegradable Films Produced from Mixtures of Alginate, Starch and Babassu Fibers

Optimal formulations for polymeric alginate films with added starch from the babassu coconut mesocarp (BCM), fiber removed from the babassu coconut epicarp (BCEF) and glycerol (G), were determined as base materials to manufacture utensils such as biodegradable packaging and shopping bags, these materials were crosslinked with CaCl2. As from an initial physical evaluation, the selected films: formulations 11 (1.5BCM + 0.38BCEF + 0.60G to solutions of 250 mL) and 13 (0.75BCM + 0.38BCEF + 2.48G to solutions of 250 mL), were submitted to a second reticulation step with the fundamental role of improving the mechanical properties. The fibers added to the polymeric matrix had a positive effect in decreasing the solubility during the two reticulation steps. Complementary trials with the selected formulations confirmed that the material showed a low water absorption tendency, a compact microstructure and relatively homogenous fiber distribution. The films obtained after the second reticulation of formulation 13 gave the best results for tensile strength and the elasticity modulus (10.31 ± 0.96 MPa and 476.13 ± 30.02 MPa, respectively). The synergetic formulations stipulated showed potential for application in pilot tests, and hence produce a biopolymer with the necessary properties for industrial application.

Submerged and non-submerged 3D bioprinting approaches for the fabrication of complex structures with the hydrogel pair GelMA and alginate/methylcellulose

The extrusion-based bioprinting of hydrogels such as gelatin methacrylate (GelMA) into structures with complex shape suffers from poor printability due to their low viscosity. The present study deals with hydrogel materials by using the mixture of cell-laden photopolymerizable GelMA as a main printing material and the mixture of alginate and methylcellulose (Alg/MC) as a support material because of its high viscosity and good thixotropic property. One extrusion-based approach is developed by printing the two mixtures into structures in an alternating layer-by-layer manner, with the electrostatic interactions between polycationic GelMA and polyanionic Alg/MC contributing to the integrity of the structures. The final printed structures are exposed to ultraviolet (UV) light to form crosslinks in GelMA through photopolymerization for further structural strengthening. The one-time UV exposure minimizes cell damage in cell-GelMA, demonstrating an advantage over those in previously reported studies that required repeated UV exposures upon the printing of each layer of a structure. The other approach is developed by submerging the extrusion nozzle into a bath of Alg/MC to print cell-laden GelMA structures, which, upon printing completion, are also subject to one-time UV exposure before the removal of the support material Alg/MC. A flower with living cells is printed to demonstrate the capability of the second approach of fabricating structures with geometric complexity. The structures printed using both approaches demonstrate a well-maintained shape fidelity, structural integrity and cell viability of over 93% up to five culturing days. The proposed two printing approaches based on the cell-GelMA and Alg/MC pair will be beneficial for exploring new opportunities in bioprinting.

Сорбционные свойства суспензионной мази с инкорпорированными природными анионными полисахаридами

Currently, there is a change in methodologies in the treatment of wounds, as a result of which the share of surgical interventions is reduced and new methods of wound care are introduced using dressings and sorption-application therapy of a new generation. The obtained experimental data on the dissolution of the standard hydrophilic ointment base and the commercial ointment Levomekol® in the Ringer-Locke model solution indicate that in real conditions, the ointment will most likely easily dissolve in physiological fluids, quickly absorb and promote the adhesion of the dressing to the wound. The sorption properties of both individual anionic polysaccharides and their mixtures in various ratios in a Ringer-Locke model solution containing the main exudate cations (Na+, K+, Ca2+) were studied in order to assess the prospects of their use as a solid phase in the development of a suspension ointment with sorption properties. This publication presents the results of the behavior of a suspension ointment with anionic hydrocolloids and a commercial ointment Levomecol® in a Ringer-Locke model solution. It is shown that a mixture of sodium alginate and Kappa-carrageenan in a ratio of 1:2 in the developed suspension ointment retained a significant amount of the model solution (24.5 g/g) in its volume for 24 hours. Increasing the sorption capacity of hydrophilic ointments based on PEO will allow you to Sorb excess exudate, create a microclimate to accelerate healing processes, and reduce tissue trauma when removing the dressing.