Alginate Gel Research Articles

A Plant-Based Animal Fat Analog Produced by an Emulsion Gel of Alginate and Pea Protein.

As the market for plant-based meat analogs grows, the development of plant-based animal fat analogs has become increasingly important. In this study, we propose an approach by developing a gelled emulsion based on sodium alginate, soybean oil (SO), and pea protein isolate. Formulations containing 15% to 70% (w/w) SO were successfully produced without phase inversion. The addition of more SO resulted in pre-gelled emulsions with a more elastic behavior. After the emulsion was gelled in the presence of calcium, the color of the gelled emulsion changed to light yellow, and the formulation containing 70% SO exhibited a color most similar to actual beef fat trimming. The lightness and yellowness values were greatly influenced by the concentrations of both SO and pea protein. Microscopic images revealed that pea protein formed an interfacial film around the oil droplets, and the oil was more tightly packed at higher oil concentrations. Differential scanning calorimetry showed that lipid crystallization of the gelled SO was influenced by the confinement of the alginate gelation, but the melting behavior was like that of free SO. FTIR spectrum analysis indicated a potential interaction between alginate and pea protein, but the functional groups of SO were unchanged. Under mild heating conditions, gelled SO exhibited an oil loss similar to that observed in actual beef trims. The developed product has the potential to mimic the appearance and slow-rendering melting attribute of real animal fat.

Photoreduction of Cr(VI) by TiO2 adsorbed gold nanoparticles and perylene as a novel organic-inorganic hybrid photocatalyst.

The photoreduction of hexavalent chromium (Cr(VI)) using TiO2 adsorbed gold nanoparticles and perylene (Au/Pe/TiO2) as a novel organic-inorganic hybrid photocatalyst has been studied. The irradiation by a Xe lamp of a Cr (VI) aqueous solution (0.1mM) with the Au/Pe/TiO2 powder resulted in the reduction of the Cr(VI). The rate of Cr(VI) reduction reached 98.3% by the irradiation for 60min. The reaction rate constant using Au/Pe/TiO2 (0.0545min-1) was higher than that of TiO2 (0.0218min-1), Pe/TiO2 (0.0303min-1), or Au/TiO2 (0.0393min-1). Gold nanoparticles and perylene synergistically accelerated the TiO2 photocatalytic reaction. This result is due to the Z-scheme electron transfer between Pe and TiO2 and the suppression of charge recombination by the gold nanoparticles. The irradiation of sunlight also led to the photocatalytic reduction of the Cr(VI) by Au/Pe/TiO2. In addition, successive reduction of the Cr(VI) was achieved by using a column packed with the Au/Pe/TiO2 powder immobilized by calcium alginate gel.

Effective adsorption and removal of malachite green and Pb2+ from aqueous samples and fruit juices by pollen–inspired magnetic hydroxyapatite nanoparticles/hydrogel beads

To deal with the environmental pollution caused by dyes and heavy metals, it is vital to design and prepare adsorbents with efficient adsorption and removal capabilities for the regulated removal of contaminants in the environment. In this work, biomimetic apatite hydrogel beads inspired by the structure of petunia pollen were produced in order to efficiently remove lead ions (Pb2+) and malachite green (MG) by adsorption. Utilizing an ionic cross-linking approach, magnetic hydroxyapatite nanoparticles (MHNPs) were encapsulated in sodium alginate gels to make hydrogel beads (MHSB) with the structure of petunia pollen. The MG and Pb2+ adsorption capacities of MHNPs were 208.06 mg/g and 475.50 mg/g, respectively, demonstrating a satisfactory adsorption ability. In addition, the magnetic hydroxyapatite nanoparticles/hydrogel microspheres demonstrated effective MG and Pb2+ adsorption and removal in mixed adsorption studies, environmental water samples, and fruit juices, as well as in real application. Due to their sound adsorption capability and stability, magnetic MHNPs and MHSB are regarded as fairly promising composite materials for the adsorption and removal of dyes and heavy metal pollutants.

Polyethylene glycol dictates the therapeutic response (anticancer and wound healing) of silver oxide nanomaterials

AbstractIn this study, polymer (polyethylene glycol [PEG] and Chitosan)‐coated silver oxide nanoparticles (NPs) have been prepared by hydrothermal method. The polymer‐encapsulated NPs are characterized by materials‐related characterization techniques such as X‐Ray diffraction (XRD), scanning electron microscope (SEM), Ultraviolet–visible (UV–Vis), photoluminescence (PL), and Fourier‐transform infrared (FTIR) spectroscopy. The crystallite size of silver oxide NPs is 43.39 nm and reduces to 34.56 nm and 30.43 nm for PEG and Chitosan functionalized NPs, respectively. SEM micrographs show the spherical morphology of the synthesized nanomaterials with the grain size of pristine, PEG, and Chitosan functionalized silver oxide NPs as 60.9 ± 14.1, 70.9 ± 10.3, and 57.2 ± 7.8 nm, respectively. The band gap of silver oxide NPs increases upon polymer functionalization. PEGlyation of silver oxide NPs has enhanced its anticancer potential significantly against liver cancer cell line (HuH‐7), shows least cell viability, and IC50 value is as low as 0.106 μg/mL and in the case of Chitosan coating 4.505 μg/mL. The antibacterial properties and biofilm inhibition are investigated against bacterial extracts of Escherichia coli and Staphylococcus aureus. The polymer‐coated silver oxide NPs have shown enhanced antibacterial potential against both S. aureus and E. coli. CAM assay is used to evaluate the wound‐healing ability of nanomaterials. Alginate gels incorporated with NPs have promoted wound healing. Our results revealed that the surface modification by PEG and Chitosan improved the therapeutic potential of silver oxide NPs.

Encapsulation of SOD in chitosan-coated gel particles of alginate or mixture of alginate and shellac for targeted intestinal delivery

The chitosan-coated alginate gel particles (CS/SA) and chitosan-coated alginate-shellac gel particles (CS/SA/Lac) were constructed to serve as a potential oral delivery system to enhance the stability and activity of superoxide dismutase (SOD) in this study. The encapsulation efficiency (EE), enzyme activity retention ratio (ER), particle structure, and SOD release behavior, as well as the effect of shellac, were evaluated. The best formula is determined by the percentage of total effective activity (PTEA).The results showed that CS/SA prepared by 0.30‰ chitosan, 1.00% CaCl2, 2.00% sodium alginate (M/G = 1:1, Mw: 38,857 kDa), and gelation solution pH 5.50 had the best chitosan shell, the strongest gel structure and the maximum PTEA which was 10.75 ± 1.45%. Based on the optimal formula, addition of shellac that formed shellac-Ca2+ microspheres in the gel network was averse to SOD encapsulation, but it significantly improved the stability of SOD in gastric conditions. By adding 15.00% shellac, the PTEA reached 16.30 ± 1.64%. At optimal formulation, SOD encapsulated in CS/SA was completely released in the stimulated intestinal fluid and accumulative release enzyme activity (EA) was 966.62 ± 103.75 (U) after 6 h. However, the CS/SA/Lac with a low swelling ratio only released SOD in stimulated colonic fluid and the EA value reached 1692.28 ± 101.82 (U) after 1 h. These findings demonstrated that CS/SA and CS/SA/Lac were excellent candidates for SOD oral administration, which was useful in the food and biomedical industries for developing functional products containing SOD.

Effect of the xanthan gum on the rheological properties of alginate hydrogels

Hydrogels are three-dimensional polymeric structures with remarkable physicochemical and mechanical properties. The selection of biopolymers as constituents of hydrogels is of great importance to enable their use in a variety of fields. The present study proposes a mixed hydrogel of alginate and xanthan gum prepared by the in-situ gelation method. Since alginate gelation is induced by calcium crosslinking, two calcium concentrations have been used in this study. In detail, the influence of xanthan gum and calcium cations on the rheological behavior of alginate hydrogels were investigated using steady shear rheology, dynamic and transient shear rheological experiments. The results showed that the hydrogels behaved like a shear-thinning material, as Carreau fluids, and that the overall viscosity of the hydrogel was dependent on both Ca2+ and xanthan gum concentrations. The length of linear viscoelastic range was influenced by xanthan gum content only at low calcium concentration, while the storage modulus (G′) was found to increase with xanthan gum and calcium content. The interpolation of mechanical spectra with a power law demonstrated that G′ and G″ were slightly dependent on the frequency and that G′ became less frequency dependent with the addition of xanthan gum. Even though the elastic contribution of the hydrogel increased with calcium and xanthan concentration, the hydrogels obtained were not able to fully recover their original structure after the application of a high load. The behavior at large amplitude oscillation strain, mimicking real processing conditions, showed that hydrogels crosslinked with a low calcium concentration were affected by xanthan gum even at lower concentrations than hydrogels crosslinked with high calcium content. Such hydrogel mixtures could find application in research in the food industry.

Hygroscopic and Malleable Dough‐Type Zn–Air Battery in a Dry Condition Utilizing Deliquescence

AbstractFlexible and rechargeable Zn–air batteries (ZAB) are promising candidates for attaining the high energy density required for next‐generation energy storage devices given their half‐open cathode configuration. However, the poor interfacial contact between the immobilized solid‐state electrolyte and porous cathode, and drying‐out of water in the electrolyte at low relative humidity (RH) of 30% or less, cause low performance and short lifespan. Herein, a novel hygroscopic dough‐type electrolyte with water‐absorbing and malleable free‐standing configuration originating from deliquescent KOH and severe gelation of sodium alginate (SA) by facile kneading is proposed. Because appropriate contents are required to absorb water from the atmosphere and obtain the manageable form of the dough used here, the materials composing the dough electrolyte, i.e., SA, water, and KOH, are precisely controlled to ensure high malleability, scalability, ionic conductivity, and good water retention capabilities. The optimized dough inhibits evaporation at low RH and lowers the interfacial resistance with the cathode via tight adhesion. The dough‐type ZABs show noteworthy maximum power density of 160 mW cm−2 with low catalyst mass loading (0.4 mg cm−2), specific capacity of 632 mAh gZn−1, and stability for 60 h at RH 30% and 120 h even at low temperature of −20 °C, producing reasonable output.

Gelation in Alginate-Based Magnetic Suspensions Favored by Poor Interaction among Sodium Alginate and Embedded Particles

Alginate gels are extensively tested in biomedical applications for tissue regeneration and engineering. In this regard, the modification of alginate gels and solutions with dispersed magnetic particles gives extra options to control the rheo-elastic properties both for the fluidic and gel forms of alginate. Rheological properties of magnetic suspensions based on Na-alginate water solution with embedded magnetic particles were studied with respect to the interfacial adhesion of alginate polymer to the surface of particles. Particles of magnetite (Fe3O4), metallic iron (Fe), metallic nickel (Ni), and metallic nickel with a deposited carbon layer (Ni@C) were taken into consideration. Storage modulus, loss modulus, and the shift angle between the stress and the strain were characterized by the dynamic mechanical analysis in the oscillatory mode. The intensity of molecular interactions between alginate and the surface of the particles was characterized by the enthalpy of adhesion which was determined from calorimetric measurements using a thermodynamic cycle. Strong interaction at the surface of the particles resulted in the dominance of the “fluidic” rheological properties: the prevalence of the loss modulus over the storage modulus and the high value of the shift angle. Meanwhile, poor interaction of alginate polymer with the surface of the embedded particles favored the “elastic” gel-like properties with the dominance of the storage modulus over the loss modulus and low values of the shift angle.

Biological treatment of perfluorooctanesulfonic acid (PFOS) using microbial capsules of a polysulfone membrane

Perfluorooctanesulfonic acid (PFOS) is a persistent organic substance that has been extensively applied in many industries and causes severe, widespread adverse health impacts on humans and the environment. The development of an effective PFOS treatment method with affordable operational costs has been expected. This study proposes the biological treatment of PFOS using microbial capsules enclosing a PFOS-reducing microbial consortium. The objective of this study was to evaluate the performance of the polymeric membrane encapsulation technique for the biological removal of PFOS. First, a PFOS-reducing bacterial consortium, composed of Paracoccus (72%), Hyphomicrobium (24%), and Micromonosporaceae (4%), was enriched from activated sludge by acclimation and subsequent subculturing with PFOS containing media. The bacterial consortium was first immobilized in alginate gel beads, then enclosed in membrane capsules by coating the gel beads with a 5% or 10% polysulfone (PSf) membrane. The introduction of microbial membrane capsules could increase PFOS reduction to between 52% and 74% compared with free cell suspension, which reduced by 14% over three weeks. Microbial capsules coated with 10% PSf membrane demonstrated the highest PFOS reduction at 80% and physical stability for six weeks. Candidate metabolites including perfluorobutanoic acid (PFBA) and 3,3,3- trifluoropropionic acid were detected by FTMS, suggesting the possible biological degradation of PFOS. In microbial membrane capsules, the initial adsorption of PFOS on the shell membrane layer enhanced subsequent biosorption and biological degradation by PFOS-reducing bacteria immobilized in the core alginate gel beads. The 10%-PSf microbial capsules exhibited a thicker membrane layer with the fabric structure of a polymer network, which maintained longer physical stability than 5%-PSf microbial capsules. This outcome suggests the potential application of microbial membrane capsules to PFOS-contaminated water treatment.

Synergistic Antimicrobial Activity of Magnetite and Vancomycin-Loaded Mesoporous Silica Embedded in Alginate Films

The aim of the present study was to obtain a hydrogel-based film as a carrier for the sustained and controlled release of vancomycin, an antibiotic commonly used in various types of infections. Considering the high-water solubility of vancomycin (>50 mg/mL) and the aqueous medium underlying the exudates, a prolonged release of vancomycin from an MCM-41 carrier was sought. The present work focused on the synthesis of malic acid coated magnetite (Fe3O4/malic) by co-precipitation, synthesis of MCM-41 by a sol-gel method and loading of MCM-41 with vancomycin, and their use in alginate films for wound dressing. The nanoparticles obtained were physically mixed and embedded in the alginate gel. Prior to incorporation, the nanoparticles were characterized by XRD, FT-IR and FT-Raman spectroscopy, TGA-DSC and DLS. The films were prepared by a simple casting method and were further cross-linked and examined for possible heterogeneities by means of FT-IR microscopy and SEM. The degree of swelling and the water vapor transmission rate were determined, considering their potential use as wound dressings. The obtained films show morpho-structural homogeneity, sustained release over 48 h and a strong synergistic enhancement of the antimicrobial activity as a consequence of the hybrid nature of these films. The antimicrobial efficacy was tested against S. aureus, two strains of E. faecalis (including vancomycin-resistant Enterococcus, VRE) and C. albicans. The incorporation of magnetite was also considered as an external triggering component in case the films were used as a magneto-responsive smart dressing to stimulate vancomycin diffusion.

In vitro expansion of hematopoietic stem cells in a porous hydrogel-based 3D culture system.

Hematopoietic stem cell (HSC) transplantation remains the most effective therapy for hematologic and lymphoid disorders. However, as the primary therapeutic cells, the source of HSCs has been limited due to the scarcity of matched donors and difficulties in ex vivo expansion. Here, we described a facile method to attempt the expansion of HSCs in vitro through a porous alginate hydrogel-based 3D culture system. We used gelatin powders as the porogen to create submillimeter-scaled pores in alginate gel bulk while pre-embedding naïve HSCs in the gel phase. The results indicated that this porous hydrogel system performed significantly better than those cultured via conventional suspension or encapsulation in non-porous alginate hydrogels in maintaining the phenotype and renewability of HSCs. Only the porous hydrogel system achieved a two-fold growth of CD34+ cells within seven days of culture, while the number of CD34+ cells in the suspension system and nonporous hydrogel showed different degrees of attenuation. The expansion efficiency of the porous hydrogel for CD34+CD38- cells was more than 2.2 times that of the other two systems. Mechanistic study via biophysical analysis revealed that the porous alginate system was competent to reduce the electron capture caused by biomaterials, decrease cellular oxygen stress, avoid oxidative protection, thus maintaining the cellular phenotype of the CD34+ cells. The transcriptomic analysis further suggested that the porous alginate system also upregulated the TNF signaling pathway and activated the NF-κB signaling pathway to promote the CD34+ cells' survival and maintain cellular homeostasis so that renewability was substantially favoured. STATEMENT OF SIGNIFICANCE: • The reported porous hydrogel system performs significantly better in terms of maintaining the phenotype and renewability of HSCs than those cultured via conventional suspension or encapsulation in non-porous alginate hydrogel. • The reported porous alginate system is competent to reduce the electron capture caused by biomaterials, decrease cellular oxygen stress, avoid oxidative protection, and therefore maintain the cellular phenotype of the CD34+ cells. • The reported porous alginate system can also upregulate the TNF signaling pathway and activate the NF-κB signaling pathway to promote the CD34+ cells' survival and maintain cellular homeostasis so that the renewability is substantially favored..

Development, RSM-Based Optimization, and Characterization of a Unique Edible Composite Film by Incorporating Clove Essential Oil Based on Sodium Alginate and Aloe vera Gel to Preserve the Quality of Blueberries

In recent years, edible composite films have attracted more attention instead of plastic packaging in the field of food packaging. Combined with clove essential oil (CO), the edible composite film based on sodium alginate (SA) and Aloe vera gel (AG) was developed. The aim of this study was to explore the effect of SA, AG, and CO on the barrier and mechanical properties of the composite films and the impact of the edible composite film on the freshness of blueberry fruits. Response surface methodology (RSM) based on single factor experiments were used to get the optimum formula with the best property. The results showed that the optimal formula was SA 15.6 gL-1, AG 90 gL-1, and CO 10 gL-1, SA, AG, and CO had significant effect on the characteristics of the films, also, the crossed-linking action of SA and AG was further confirmed by characterization, while CO significantly influenced barrier and mechanical property and improved the antibacterial activity of the film. The composite film kept great hardness, less weight loss, more soluble solid, and more vitamin C of blueberries, proving the bacteriostatic activity of AG and CO. The results suggest that the edible composite film has an enormous potential in extending the shelf-life of blueberries with this formula.

Сонохимическое микроструктурирование альгината натрия для повышения его эффективности в технологии хлебобулочных изделий

Algae are a source of many biologically active compounds that can be used in food production to expand the range of functional products. For instance, sodium alginate possesses a complex of scientifically proven biologically active properties. In the food industry, it usually serves as a thickener, stabilizer, gelatio n agent, and water-retaining agent. The biological activity of this polysaccharide and its effect on the technological properties of food systems depend on the molecular weight and particle size uniformity. The present research objective was to study the method of sonochemical microstructuring of sodium alginate to increase its biological activity and efficiency as part of v arious bakery formulations.
 The research featured alginate gels, yeast suspensions of Saccharomyces cerevisiae, and bakery products. The sonochemical microstructuring of sodium alginate involved a low-frequency ultrasonic treatment at 240, 435, and 630 W/L and 50°C for 20, 25, and 30 min. The effect of the treatment included the following indicators: particle morphology vs. distribution of the hydrodynamic particle diameter in a dispersed medium, antioxidant activity, dynamic viscosity, in vitro bioactivity, and bioavailability against Paramecium caudatum and S. cerevisiae. The quality assessment of bakery products followed State Standard 58233-2018.
 The process of sonochemical microstructuring depolymerized large particles of sodium alginate into shorter ones: 5670 nm – 30.6%, 502 nm – 53.4%, 56.1 nm – 16%. It increased the antioxidant activity by 7 times and the potential in vitro bioactivity by 3.9%. The microstructured sodium alginate improved the fermentation activity of S. cerevisiae and reduced the yeast biomass by 8%. The resulting bakery products had a greater porosity by 5.9% and antioxidant activity by 3.7 times.
 The sonochemical microstructuring reduced the particle size of sodium alginate, as well as increased its biological activity. The sonochemically microstructured sodium alginate demonstrated a great potential for baked foods.

Formation of Alginate/Chitosan Interpenetrated Networks Revealed by EPR Spectroscopy.

This study analyzes the physico-chemical properties of interpenetrated polymer networks (IPNs) and semi-IPN resulting from cross-linking chitosan with glutaraldehyde and alginate with Ca2+ cations, as a function of the order in which the cross-linking agents are added to the polymer mixture. Three physico-chemical methods were used to assess the differences between systems: rheology, IR spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. While rheology and IR spectroscopy are commonly used to characterize gel materials, EPR spectroscopy is rarely used, but has the advantage of providing local information about the dynamics of a system. The rheological parameters, which describe the global behavior of the samples, show that semi-IPN systems have a weaker gel behavior and the order of introducing the cross-linker in the polymer systems plays a role. The IR spectra of samples resulting by adding only Ca2+ or Ca2+ as the first cross-linker are similar to that of the alginate gel, while the spectra of samples in which glutaraldehyde is firstly added resemble the chitosan gel spectrum. Using spin-labeled alginate and spin-labeled chitosan, we monitored the changes occurring in the dynamic of the spin labels due to the formation of IPN and semi-IPN. The results show that the order of adding the cross-linking agents influences the dynamic of the IPN network, and that the formation of the alginate network determines the characteristics of the entire IPN system. The EPR data were correlated with the rheological parameters and IR spectra of the analyzed samples.

Neo-cartilage formation using human nondegenerate versus osteoarthritic chondrocyte-derived cartilage organoids in a viscoelastic hydrogel.

Current regenerative cartilage therapies are associated with several drawbacks such as dedifferentiation of chondrocytes during expansion and the formation of fibrocartilage. Optimized chondrocyte expansion and tissue formation could lead to better clinical results of these therapies. In this study, a novel chondrocyte suspension expansion protocol that includes the addition of porcine notochordal cell-derived matrixwas used to self-assemble human chondrocytes from osteoarthritic (OA) and nondegenerate (ND) origin into cartilage organoids containing collagen type II and proteoglycans. Proliferation rate and viability were similar for OA and ND chondrocytes and organoids formed had a similar histologic appearance and gene expression profile. Organoids were then encapsulated in viscoelastic alginate hydrogels to form larger tissues. Chondrocytes on the outer bounds of the organoids produced a proteoglycan-rich matrix to bridge the space between organoids. In hydrogels containing ND organoids some collagen type I was observed between the organoids. Surrounding the bulk of organoids in the center of the gels, in both OA and ND gels a continuous tissue containing cells, proteoglycans and collagen type II had been produced. No difference was observed in sulphated glycosaminoglycan and hydroxyproline content between gels containing organoids from OA or ND origin after 28 days. It was concluded that OA chondrocytes, which can be harvested from leftover surgery tissue, perform similar to ND chondrocytes in terms of human cartilage organoid formation and matrix production in alginate gels. This opens possibilities for their potential to serve as a platform for cartilage regeneration but also as an in vitro model to study pathways, pathology, or drug development.

Emerging of a new CD3+CD31HCD184+ tang cell phenothype in Sjögren's syndrome induced by microencapsulated human umbilical cord matrix-derived multipotent stromal cells.

Sjögren's syndrome (SS) is an autoimmune disease hallmarked by infiltration and destruction of exocrine glands. Currently, there is no therapy that warrants full recovery of the affected tissues. Umbilical cord-derived multipotent stromal cells, microincapsulated in an endotoxin-free alginate gel (CpS-hUCMS), were shown to modulate the inflammatory activity of PBMCs in SS patients in vitro, through release of soluble factors (TGFβ1, IDO1, IL6, PGE2, VEGF). These observations led us to set up the present study, aimed at defining the in vitro effects of CpS-hUCMS on pro- and anti-inflammatory lymphocyte subsets involved in the pathogenesis of SS. Peripheral blood mononuclear cells (PBMCs) upon collection from SS patients and matched healthy donors, were placed in co-culture with CpS-hUCMS for five days. Cellular proliferation and T- (Tang, Treg) and B- (Breg, CD19+) lymphocyte subsets were studied by flow cytometry, while Multiplex, Real-Time PCR, and Western Blotting techniques were employed for the analysis of transcriptome and secretome. IFNγ pre-treated hUCMS were assessed with a viability assay and Western Blotting analysis before co-culture. After five days co-culture, CpS-hUCMS induced multiple effects on PBMCs, with special regard to decrease of lymphocyte proliferation, increase of regulatory B cells and induction of an angiogenic T cell population with high expression of the surface marker CD31, that had never been described before in the literature. We preliminarily showed that CpS-hUCMS can influence multiple pro- and anti-inflammatory pathways that are deranged in SS. In particular, Breg raised and a new Tang phenothype CD3+CD31HCD184+ emerged. These results may considerably expand our knowledge on multipotent stromal cell properties and may open new therapeutic avenues for the management of this disease, by designing ad hoc clinical studies.

In-situ fabrication of novel Au nanoclusters-Cu2+@sodium alginate/hyaluronic acid nanohybrid gels for cuproptosis enhanced photothermal/photodynamic/chemodynamic therapy via tumor microenvironment regulation

Multimodal combined therapy (MCT) is an emerging avenue to eliminate tumor cells by the synergistic effect of various therapeutic methods. However, the complex tumor microenvironment (TME) is becoming the key barrier to the therapeutic effect of MCT due to the excessive existence of H+ ions, H2O2, and glutathione (GSH), the lack of O2, and the relaxation of ferroptosis. To overcome these limitations, smart nanohybrid gels with excellent biocompatibility, stability and targeting function were prepared by using gold nanoclusters as cores and an in situ cross-linking composite gel of sodium alginate (SA)/hyaluronic acid (HA) as the shell. The obtained Au NCs-Cu2+@SA-HA core–shell nanohybrid gels possessed near-infrared light response synergistically benefitting photothermal imaging guided photothermal therapy (PTT) and photodynamic therapy (PDT). Meanwhile, the H+-triggered release of Cu2+ ions from the nanohybrid gels not only induces cuproptosis to avoid the relaxation of ferroptosis, but also catalyzes H2O2 in the TME to generate O2 to simultaneously improve the hypoxic microenvironment and PDT effect. Furthermore, the released Cu2+ ions could consume the excessive GSH to form Cu+ ions effectively, which caused the formation of hydroxyl free radicals (·OH) to kill tumor cells, synergistically realizing GSH consumption-enhanced PDT and chemodynamic therapy (CDT). Hence, the novel design in our work provides another research avenue for cuproptosis-enhanced PTT/PDT/CDT via TME modulation.

Eco-Friendly Starch Composite Supramolecular Alginate-Ca2+ Hydrogel as Controlled-Release P Fertilizer with Low Responsiveness to Multiple Environmental Stimuli.

Environmentally friendly fertilizers (EFFs) have been developed to improve fertilizer efficiency and minimize adverse environmental impacts, but their release behavior under various environmental conditions has been less explored. Using phosphorus (P) in the form of phosphate as a model nutrient, we present a simple method for preparing EFFs based on incorporating the nutrient into polysaccharide supramolecular hydrogels using Cassava starch in the Ca2+-induced cross-link gelation of alginate. The optimal conditions for creating these starch-regulated phosphate hydrogel beads (s-PHBs) were determined, and their release characteristics were initially evaluated in deionized water and then under various environmental stimuli, including pH, temperature, ionic strength, and water hardness. We found that incorporating a starch composite in s-PHBs at pH = 5 resulted in a rough but rigid surface and improved their physical and thermal stability, compared with phosphate hydrogel beads without starch (PHBs), due to the dense hydrogen bonding-supramolecular networks. Additionally, the s-PHBs showed controlled phosphate-release kinetics, following a parabolic diffusion with reduced initial burst effects. Importantly, the developed s-PHBs exhibited a promising low responsiveness to environmental stimuli for phosphate release even under extreme conditions and when tested in rice field water samples, suggesting their potential as a universally effective option for large-scale agricultural activities and potential value for commercial production.

Swelling of Homogeneous Alginate Gels with Multi-Stimuli Sensitivity.

A new two-step method is suggested for the preparation of homogeneous alginate gels. In the first step, alginate chains are weakly bonded by Ca2+ ions in an aqueous solution with a low pH. In the next step, the gel is immersed into a strong solution of CaCl2 to finalize the cross-linking process. Homogeneous alginate gels preserve their integrity in aqueous solutions with a pH ranging from 2 to 7 and ionic strength in the interval from 0 to 0.2 M, at temperatures ranging from room temperature up to 50 °C, and can be used in biomedical applications. The immersion of these gels into aqueous solutions with low pH induces the partial breakage of ionic bonds between chains (treated as gel degradation). This degradation affects the equilibrium and transient swelling of homogeneous alginate gels and makes them sensitive to the history of loading and environmental conditions (pH, ionic strength and temperature of aqueous solutions). As sensitivity to the environmental stimuli is a characteristic feature of polymer networks connected by catch bonds, homogeneous alginate gels may serve as a simple model, mimicking the behavior of more sophisticated structures in living matter.

Physiological and Biochemical Characteristics, and Biotechnological Potential of Hydrolitic Haloalkalitolerant Bacteria of Soda Sludge Storage

Peculiarities of manifestation of hydrolytic activity of haloalkalitolerant bacteria Pseudomonas peli 3-T, Microbacterium kitamiense 16-DB, and Bacillus aequororis 5-DB, isolated from the soil of the territory of the soda sludge storage and the soda sludge of the functioning sludge reservoir of Berezniki Soda Plant (Perm Territory, Russia) were studied. It was shown that the maximum activity of extracellular lipases and amylases of the three studied bacteria were manifested at pH 11 and a high concentration of sodium chloride (50–200 g/L). Cultivation of P. peli 3-T on a mineral medium with 0.5% glycerol (source of carbon) and 0.03% urea (source of nitrogen) makes it possible to obtain biomass (6.9 g/L) and activity of extracellular lipase (1.26 U/L) and lipase associated with cells (3.02 U/mg dry cells) with a high economic ratio of substrate consumption (138%). The efficiency of immobilization of P. peli 3-T and B. aequororis 5-DB cells for use in lipid and starch biotransformation was shown. P. peli 3-T cells immobilized by adsorption on kaolin and incorporated into the structure of barium alginate and agarose gels retained from 40.4 to 63.8% of the cell lipase activity in suspension. B. aequororis 5-DB cells immobilized by adsorption on kaolin retained 42.5% of lipase and 90.7% of amylase activity as compared to the initial ones. At the same time, the activities of the P. peli 3-T and B. aequororis 5-DB enzymes were preserved during 6 consecutive reactions. The amylase activity of immobilized M. kitamiense 16-DB cells by adsorption on kaolin and chitosan decreased to 2.7–3.5% of the initial value and was completely inhibited upon immobilization by cell’s entrapment into barium alginate gels or agarose gels.