Chitosan–sodium alginate polyion complexes as fuel cell membranes

Facile synthesis of carbon-coated silicon nanocomposite with tremella-like porous structure for superior lithium-ion storage

Silicon/carbon (Si/C) composites have been envisaged as one of the most promising anode materials for the next-generation lithium-ion batteries (LIBs) with high energy density, and constructing reasonable and cross-scale structures is crucial adjective for high-performance Si/C electrodes. Herein, a facile synthesis strategy was developed by combining gel coating, carbonization, and molten salt-assisted magnesiothermic reduction (MSA-MR), and a unique tremella-like Si/C composite with internal void structure (IV-Si/C) was successfully prepared. The working mechanisms of both sodium alginate (SA) and molten salt (NaCl) on the successful preparation of the target IV-Si/C nanocomposite were also investigated in detail. It was demonstrated that, α-L-guluronic (G) blocks in SA can be cross-linked with cations to promote the interactions with silicon dioxide (SiO2) particles, boosting uniform distribution of nanosized Si particles in the SA-derived carbon matrix. Meanwhile, NaCl generated from SA not only effectively boosted the crystallization of SiO2 during the high-temperature carbonization process but also can effectively inhibit the formation of inert SiC and strengthen reduction of carbon during the MSA-MR treatment, resulting in successful preparation of the tremella-like Si/C composite with abundant internal voids. Benefitting from its unique structure, when used as an alternative anode material for electrochemical lithium storage, the as-obtained IV-Si/C nanocomposite delivered a high reversible specific capacity of 1899.6 mAh g-1 with an initial Coulomb efficiency of 75.96% and superior rate capability and long-term cycling stability. This facile and low-cost synthesis strategy may shed light on the controllable preparation of functional nanomaterials with unique structures, especially high-performance Si/C anode materials for their large-scale application in LIBs.

Creating ultra-strong and recyclable green plastics from marine-sourced alginate-chitosan nanowhisker nanocomposites for controlled release urea fertilizer

In response to the pressing environmental challenge posed by petroleum-derived plastics, the development of green plastics derived from all-biomass nanocomposites offers promising solutions. However, conventional nanocomposites often prioritize enhanced stiffness at the expense of flexibility. We introduce sodium alginate (SA)/chitosan nanowhisker (CSW) nanocomposites, derived entirely from marine-sourced all-biomass, to create ultra-strong and flexible green plastics. Through the synergistic interaction between SA and CSW, these nanocomposites demonstrate simultaneous stiffening and toughening, overcoming the traditional trade-off. Two key mechanisms contribute: geometric reinforcement from the needle-like structure of CSW and electrostatic reinforcement at the interface between oppositely charged CSW and SA. Compared to control SA, the SA/CSW nanocomposites exhibit remarkable enhancements in tensile modulus, strength, and stretchability, by 49%, 85%, and 55%, respectively (7.6 GPa, 223.3 MPa, 14.7%). Cellulose nanocrystals, serving as a control, only stiffen the nanocomposites, adhering to the typical trade-off. Biodegradability in compost can be tailored based on the type of nanofillers. Due to the water resistance of CSW, SA/CSW nanocomposites are proven effective for the controlled release of urea fertilizer in agricultural applications. With recyclability and superior mechanical properties, these marine-sourced green plastics offer a sustainable alternative to conventional plastics, promising significant impact in the eco-plastic industry.

Structural and Release Properties of Combined Curcumin Controlled-Release Tablets Formulated with Chitosan/Sodium Alginate/HPMC

Controlled-release tablets offer several benefits, such as controlled release, odor masking, ease of use, stability, extended shelf life, and reduced production costs. This study developed combined curcumin controlled-release tablets (CCCTs) to increase the bioavailability of curcumin with hydroxypropyl methylcellulose (HPMC), chitosan, and sodium alginate. The hardness of the CCCTs was 5.63-1.98 kgf, friability was 0.00-1.22%, and disintegration time was 0.00-401.25 min. Differential scanning calorimetry and Fourier-transform infrared spectroscopy indicated a high compatibility between the excipients and curcumin. CCCTs with chitosan formed a gel structure, impeded disintegration, and reduced the release rate to 72.5% in simulated gastric fluid. In simulated intestinal fluid, CCCT with the HPMC-sodium alginate group formed a polyelectrolyte membrane hydrogel to prolong release from 6 to 12 h. This study developed various CCCT formulations that can be delivered through the gastric or intestinal tracts, using chitosan and HPMC-sodium alginate as excipients, respectively. CCCT can be used as a reference strategy for controlled-release curcumin delivery in the functional and healthcare supplement development.

Encapsulation of polyketide colorants in chitosan and maltodextrin microparticles

This study aimed to encapsulate Talaromyces amestolkiae colorants in maltodextrin and chitosan microparticles using the spraydrying technique and to evaluate the biopolymers' capacities to protect the fungal colorant against temperature (65 °C) and extreme pH (2.0 and 13.0). The compact microparticles exhibited smooth or indented surfaces with internal diameters ranging between 2.58-4.69 μm and ζ ~ -26 mV. The encapsulation efficiencies were 86 % and 56 % for chitosan and maltodextrin microparticles, respectively. The shifted endothermic peaks of the free colorants indicated their physical stabilization into microparticles. The encapsulated colorants retained most of their absorbance (compared to the 0 h) even after 25 days at 65 °C. Contrary, the free colorant presented almost no absorbance after 1 day under the same conditions. Colorants in chitosan and maltodextrin matrices also partially maintained their colorimetric and fluorometric properties at acidic pH. However, only maltodextrin improved the resistance of the red colorant to alkaline environments. For the first time, the potential of polysaccharide-based microparticles to preserve polyketide colorants was demonstrated using 3D fluorescence. Therefore, this study demonstrated an alternative in developing functional products with natural color additives.

Fabrication and property of the avermectin-attapulgite composites regulated by mixed-surfactants and sodium alginate

OA-AP, DTAB-AP, DDBAB-AP complexes were synthesized by introducing surfactants of OA, DTAB and DDBAB into attapulgite (AP). The complexes were systematically characterized. The appearance of new diffraction peaks at low angle indicated a new lamellar structure of OA (DTAB, DDBAB)-AP complexes. Then, the pesticide avermectin (AV) composites of AV/DTAB-OA-AP, AV/DDBAB-OA-AP, sodium alginate (SA) @AV/DTAB-OA-AP and SA@AV/DDBAB-OA-AP were prepared and investigated detailedly. The basal spacings of AV/DTAB-OA-AP and AV/DDBAB-OA-AP were bigger than those of OA-AP and DTAB(DDBAB)-AP. The existences of AV, surfactants and SA molecules of the composites were further confirmed. Furthermore the effect of SA on AV release behaviors of SA@AV/DTAB (DDBAB)-OA-AP microspheres was investigated and compared. Compared to AV/DTAB (DDBAB)-OA-AP, the released rate of the microspheres decreased remarkably. The AV release behaviors of AV/DTAB (DDBAB)-OA-AP could be fitted with pseudo second-order model, while the first-order model was better to describe those of the microspheres. Finally, the bioassay of the microspheres were studied and analyzed. The microspheres had a longer duration and control effect on Mythimna separata. This study could be helpful to provide a pesticide delivery system to improve the utilization efficiency of pesticides.

Green Synthesis of Cation Exchange Membranes: A Review

Cation exchange membranes (CEMs) play a significant role in the transition to a more sustainable/green society. They are important components for applications such as water electrolysis, artificial photosynthesis, electrodialysis and fuel cells. Their synthesis, however, is far from being sustainable, affecting safety, health and the environment. This review discusses and evaluates the possibilities of synthesizing CEMs that are more sustainable and green. First, the concepts of green and sustainable chemistry are discussed. Subsequently, this review discusses the fabrication of conventional perfluorinated CEMs and how they violate the green/sustainability principles, eventually leading to environmental and health incidents. Furthermore, the synthesis of green CEMs is presented by dividing the synthesis into three parts: sulfonation, material selection and solvent selection. Innovations in using gaseous SO3 or gas-liquid interfacial plasma technology can make the sulfonation process more sustainable. Regarding the selection of polymers, chitosan, cellulose, polylactic acid, alginate, carrageenan and cellulose are promising alternatives to fossil fuel-based polymers. Finally, water is the most sustainable solvent and many biopolymers are soluble in it. For other polymers, there are a limited number of studies using green solvents. Promising solvents are found back in other membrane, such as dimethyl sulfoxide, Cyrene™, Rhodiasolv® PolarClean, TamiSolve NxG and γ-valerolactone.

A chitosan-coated lentinan-loaded calcium alginate hydrogel induces broad-spectrum resistance to plant viruses by activating Nicotiana benthamiana calmodulin-like (CML) protein 3

Control of plant virus diseases largely depends on the induced plant defence achieved by the external application of synthetic chemical inducers with the ability to modify defence-signalling pathways. However, most of the molecular mechanisms underlying these chemical inducers remain unknown. Here, we developed a chitosan-coated lentinan-loaded hydrogel and discovered how it protects plants from different virus infections. The hydrogel was synthesized by coating chitosan on the surface of the calcium alginate-lentinan (LNT) hydrogel (SL-gel) to form a CSL-gel. CSL-gels exhibit the capacity to prolong the stable release of lentinan and promote Ca2+ release. Application of CSL-gels on the root of plants induces broad-spectrum resistance against plant viruses (TMV, TRV, PVX and TuMV). RNA-seq analysis identified that Nicotiana benthamiana calmodulin-like protein gene 3 (NbCML3) is upregulated by the sustained release of Ca2+ from the CSL-gel, and silencing and overexpression of NbCML alter the susceptibility and resistance of tobacco to TMV. Our findings provide evidence that this novel and synthetic CSL-gel strongly inhibits the infection of plant viruses by the sustainable release of LNT and Ca2+ . This study uncovers a novel mode of action by which CSL-gels trigger NbCML3 expression through the stable and sustained release of Ca2+ .

Biosorption of p-chloro meta xylenol (PCMX) by bacterium-encapsulated calcium alginate beads in a novel plug flow process

P-Chloro-Meta-Xylenol (PCMX) is a widely used disinfectant. In the current pandemic scenario, its consumption has increased largely, and as a result, wastewater is loaded heavily with PCMX as a contaminant. Remediation of this ecologically toxic phenolic compound is therefore a burning issue. This study proposes an eco-friendly biosorption-based remediation technique to remove PCMX. A novel isolated phenol-resistant gram-negative bacterium, Pandoraea sp. strain BT102, is first encapsulated in biopolymeric calcium alginate beads. These beads are packed in a long adsorption tube and the contaminated water was passed through this packed tube resembling a plug flow reactor. This unique plug-flow set-up is capable of reducing PCMX concentration from 100 mg L^-1 to 2.85 μg L^-1 within 4 h using only 30 g of adsorbent, resulting in 99.99% removal efficiency. Adsorption isotherms and kinetics are studied using batch experimental data. A PCMX loading capacity of the encapsulated calcium alginate beads is found to be 961.7 mg g^-1, and the Freundlich isotherm results suggested the phenomenon of cooperative adsorption. A good agreement of the pseudo-second-order kinetic model along with the intra-particle diffusion model suggests a multilayer diffusion-controlled adsorption process. Biosorption of PCMX by the bacterium-modified beads was confirmed by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and Fourier-Transform Infrared spectroscopy (FT-IR) analyses. The application of multivariate model-based Response Surface Methodology (RSM) reveals flow rate to be the most important factor controlling the rate of bioremediation.

Alginate/PVA Polymer Electrolyte Membrane Modified by Hydrophilic Montmorillonite for Structure and Selectivity Enhancement for DMFC Application

Nafion is a commercial membrane that is widely used in direct methanol fuel cells (DMFC) but has critical constraints such as being expensive and having high methanol crossover. Efforts to find alternative membranes are actively being carried out, including in this study, which looks at producing a Sodium Alginate/Poly (Vinyl Alcohol) (SA/PVA) blended membrane with modification by montmorillonite (MMT) as an inorganic filler. The content of MMT in SA/PVA-based membranes varied in the range of 2.0-20 wt% according to the solvent casting method implemented. The presence of MMT was seen to be most optimal at a content of 10 wt%, achieving the highest proton conductivity and the lowest methanol uptake of 9.38 mScm^-1 and 89.28% at ambient temperature, respectively. The good thermal stability, optimum water absorption, and low methanol uptake of the SA/PVA-MMT membrane were achieved with the presence of MMT due to the strong electrostatic attraction between H⁺, H₃O⁺, and ^-OH ions of the sodium alginate and PVA polymer matrices. The homogeneous dispersion of MMT at 10 wt% and the hydrophilic properties possessed by MMT contribute to an efficient proton transport channel in SA/PVA-MMT membranes. The increase in MMT content makes the membrane more hydrophilic. This shows that the loading of 10 wt% MMT is very helpful from the point of view of sufficient water intake to activate proton transfer. Thus, the membrane produced in this study has great potential as an alternative membrane with a much cheaper cost and competent future performance.

The improvement of periodontal tissue regeneration using a 3D-printed carbon nanotube/chitosan/sodium alginate composite scaffold

Periodontal disease is a common disease in the oral field, and many researchers are studying periodontal disease and try to find some biological scaffold materials to make periodontal tissue regenerative. In this study, we attempted to construct a carbon nanotube/chitosan/sodium alginate (CNT/CS/AL) ternary composite hydrogel and then prepare porous scaffold by 3D printing technology. Subsequently, characterizing the materials and testing the mechanical properties of the scaffold. Additionally, its effect on the proliferation of human periodontal ligament cells (hPDLCs) and its antibacterial effect on Porphyromonas gingivalis were detected. We found that CNT/CS/AL porous composite scaffolds with uniform pores could be successfully prepared. Moreover, with increasing CNT concentration, the degradation rate and the swelling degree of scaffold showed a downward trend. The compressive strength test indicated the elastic modulus of composite scaffolds ranged from 18 to 80 kPa, and 1% CNT/CS/AL group had the highest quantitative value. Subsequently, cell experiments showed that the CNT/CS/AL scaffold had good biocompatibility and could promote the proliferation of hPDLCs. Among 0.1%-1% CNT/CS/AL groups, the biocompatibility of 0.5% CNT/CS/AL scaffold performed best. Meanwhile, in vitro antibacterial experiments showed that the CNT/CS/AL scaffold had a certain bacteriostatic effect on P. gingivalis. When the concentration of CNT was more than 0.5%, the antimicrobial activity of composite scaffold was significantly promoted, and about 30% bacteria were inactivated. In conclusion, this 3D-printed CNT/CS/AL composite scaffold, with good material properties, biocompatibility and bacteriostatic activity, may be used for periodontal tissue regeneration, providing a new avenue for the treatment of periodontal disease.

Contribution of halloysite as nanotubular clay mineral on mechanism and adsorption rate of Cd(II) onto nanocomposites alginate-halloysite

In this work nanocomposites based on alginate (Alg) and halloysite as a nanotubular clay (Hy) were developed. Characterization techniques reveal that Hy/Alg nanocomposites are cation exchangers with predominantly negative charge density and good thermal stability. The adsorption equilibrium of Cd(II) in aqueous solution onto Hy/Alg nanocomposites revealed that by increasing the mass of halloysite in the nanocomposite, the adsorption capacity diminished significantly due to the halloysite-alginate interactions. Maximum adsorption capacities of 8, 65, 88, and 132 mg/g of Cd(II) were obtained for samples Hy, Hy/Alg 50%, Hy/Alg 95%, and Alg, respectively. In addition, the adsorption equilibrium of Cd(II) on the Hy/Alg bionanocomposites was affected by the pH and temperature of the solution, demonstrating the presence of electrostatic interactions during adsorption and that this is an exothermic process. The controlling mechanism of adsorption was cation exchange influenced by electrostatic forces. The Cd(II) adsorption rate studies were interpreted by the diffusion-permeation model and reveal that the presence of Hy in the structure of the nanocomposites enhances the permeation coefficient, that is, the adsorption rate was increased. The values of the permeation coefficient varied from 1.95 × 10^-7 to 8.50 × 10^-7 cm²/s for Hy/Alg 50% and from 1.70 × 10^-7 to 3.55 × 10^-7 cm²/s for Hy/Alg 95%.

Synthesis of biochar-CoFe2O4 nanocomposite for adsorption of methylparaben from wastewater under full factorial experimental design

The presence of endocrine-disrupting chemicals in municipal wastewater has emerged as a threat to human health and the environment. Therefore, this study aimed to develop biochar-cobalt ferrite (BCF) nanocomposite for the removal of methylparaben from water under the full factorial experimental design of 4 factors with 3 levels (3⁴). The biochar-CoFe₂O₄ nanocomposite was developed by co-precipitation method from cobalt ferrite and biochar of Eucalyptus tree bark. Adsorbent surface morphology and functional and elemental composition were carried out by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDS) techniques which showed the presence of cracks with a rough surface, reasonable surface chemical composition, and many chemical functional groups, respectively. The experimental and predicted adsorption efficiencies ranged from 25.3 to 85.6% and 21.8 to 80.3%, respectively. The maximum adsorption performance (85.6%) reduced the methylparaben concentration from 27.5 to 4.0 mg/L at the optimum condition of adsorbent dose of 55 mg/100 mL, pH 6, contact time 90 min, and the initial methylparaben concentration of 27.5 mg/L. However, the adsorbent dose was the most influential main factor whereas the least influential was the interaction between solution pH and contact time under the regression model. The model also showed that 69% methylparaben removal was described by the regression model. The experimental data best fitted with the Freundlich model indicate multilayer adsorption which is the implication of physisorption. The sorption mechanism is attributed to Vander Waals forces, H-bonding, and dipole interaction. This BCF nanocomposite adsorbent appears to be promising for the removal of methylparaben from wastewater, but a further optimization process is essential to boost the treatment performance.

Shifting to transparent/hazy properties: The case of alginate/network cellulose all-polysaccharide composite films

Light management films emerged entirely from natural polymers with tunable haze properties are developed via facile approach for optoelectronics application. A novel green method simply based on the blending of network cellulose (NC)/water suspension with alginate aqueous solution is proposed. The unique network cellulose suspension created by a controlled hydrolysis of microcrystalline cellulose acts as the scatterer media while alginate serves as the transparent host matrix. Network cellulose features isotropic intertwined network of nanofibers that contributes to light scatting and produce optical haze. The opaque but hazy network cellulose is dispersed purposefully in the alginate film, where its original properties are preserved owing to its poor solubility in water. Additionally, the dispersion will notably increase the roughness of the composite film surface and act as a light scatterer. Eventually, composite alginate/network cellulose (CaAlg/NC) film with high transparency (>94%) and customized haze (15-73%) at 550 cm^-1 wavelength is fabricated. Herein, we successfully combine the transparent alginate with the opaque but hazy "network cellulose" of uniformly distributed nanofibers by a facile and scalable blending to fabricate transparent and hazy all-natural composite films. The fabricated all-polysaccharide films exhibited high transparency with tailored transmission haze. The film is highly fitting for large-scale production and adequate to meet different haze requirements to accommodate different applications such as privacy protection films and antiglare/antireflection coatings. This article is protected by copyright. All rights reserved.

Alginate: Enhancement Strategies for Advanced Applications

Alginate is an excellent biodegradable and renewable material that is already used for a broad range of industrial applications, including advanced fields, such as biomedicine and bioengineering, due to its excellent biodegradable and biocompatible properties. This biopolymer can be produced from brown algae or a microorganism culture. This review presents the principles, chemical structures, gelation properties, chemical interactions, production, sterilization, purification, types, and alginate-based hydrogels developed so far. We present all of the advanced strategies used to remarkably enhance this biopolymer's physicochemical and biological characteristics in various forms, such as injectable gels, fibers, films, hydrogels, and scaffolds. Thus, we present here all of the material engineering enhancement approaches achieved so far in this biopolymer in terms of mechanical reinforcement, thermal and electrical performance, wettability, water sorption and diffusion, antimicrobial activity, in vivo and in vitro biological behavior, including toxicity, cell adhesion, proliferation, and differentiation, immunological response, biodegradation, porosity, and its use as scaffolds for tissue engineering applications. These improvements to overcome the drawbacks of the alginate biopolymer could exponentially increase the significant number of alginate applications that go from the paper industry to the bioprinting of organs.

DEVELOPMENT OF FUNCTIONAL HYBRID SCAFFOLDS FOR WOUND HEALING APPLICATIONS

Hybrid hydrogels composed of chitosan (CS) and hyaluronic acid (HA) and collagen (Coll) were prepared by polyelectrolyte complex self-assembly. These scaffolds displayed a good intermingling of the polymeric chains, with porosities above 80% and good interconnected structures with pore sizes lying between 30–115 μm. The ionic interactions between CS and HA make the scaffolds have larger storage modulus and longer LVR regions than their pure counterparts. Both quantities progressively decrease as the HA and Coll concentrations in the formulation rise. These hybrid hydrogels showed good swelling extents from ca. 420 to ca. 690% and suitable resistance to enzymatic degradation, which was slightly lower for scaffolds containing CS to larger extents or Coll in the formulation. All scaffolds were largely cytocompatible and allowed the proliferation of both mouse fibroblast and human keratinocytes with their infiltration inside, thus becoming optimal matrices for intended tissue engineering applications as well as transdermal drug delivery depots.

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Hybrid scaffolds were obtained by polyelectrolyte ionic self-assembly

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Scaffolds were largely porous with suitable pore sizes for cell proliferation

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Scaffolds showed exceptional swelling and good resistance to enzymatic attack

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They were nontoxic and enabled cell proliferation and infiltration inside the scaffold

Anti-excitotoxicity and neuroprotective action of asiaticoside encapsulated polymeric nanoparticles in pilocarpine rodent seizure model

Asiaticoside (ASI), an ursane-type triterpenoid saponin, isolated from the memory enhancing herb Centella asiatica, is known for its neuroprotective activities. Here the anti-excitotoxicity and neuro protective effects of ASI encapsulated alginate chitosan nanoparticles (ACNPs) were evaluated in pilocarpine (PC) induced seizure in mice model. ACNPs were prepared by ionic gelation-polyelectrolyte complex method and their physicochemical characterization was carried out by TEM, SEM, DLS, XRD and FT-IR. Subsequently their encapsulation efficiency (EE), in vitro drug release, cell viability, seizure score, DNA fragmentation and mRNA expression of regulatory stress markers were evaluated. Membrane permeability of ACNPs in brain, histopathology and biological TEM and SEM analyses were also carried out. TEM of ACNPs showed spherical morphology with a particle size of 200-400 nm. DLS of ACNPs displayed an average size of 486.2 nm with polydispersity index (PDI) of 0.567 and zeta potential of -14.1 mV. ACNPs achieved high EE (> 90%) and controlled release (10%). Biological evaluation studies revealed ACNPs as non-toxic to mouse neural stem cells (mNSCs). They displayed enhanced brain permeability and attenuated seizure. Our results confirmed ACNPs as effective in crossing the brain membrane barrier and mitigating seizure severity induced by PC.

Preparation, Characterization and Dielectric Properties of Alginate-Based Composite Films Containing Lithium Silver Oxide Nanoparticles

Polymer composites have found applications in diverse areas, ranging from the manufacturing of portable electronic devices to the fabrication of bioactive agent carriers. This article reports the preparation of composite films consisting of sodium alginate (SA) and lithium silver oxide (LAO) nanoparticles. The films are generated by solution casting; whereas the nanoparticles are fabricated by using the hydrothermal method. The effects of the nanoparticles on the morphological, thermal, and dielectric properties of the films are examined by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Electrical measurements are also performed to determine the dielectric constant (ε'), dielectric loss (ε″), AC conductivity (σac), electrical moduli (M' and M″), and impedance (Z' and Z″). The composite films are shown to be crystalline in nature, with nanoparticles having a diameter of 30-45 nm effectively disseminated in the polymer matrix. They also display good dielectric properties. Our results suggest that the films warrant further exploration for possible use in microelectronic applications.

Preparation, in vitro and in vivo evaluation of chitosan-sodium alginate-ethyl cellulose polyelectrolyte film as a novel buccal mucosal delivery vehicle

This paper describes the development of a film comprising chitosan (CS), sodium alginate (SA), and ethyl cellulose (EC) for buccal mucosal administration. A film of CS-SA unidirectional release drug-containing water-repellent layer EC was produced by interfacial reaction solvent-drying technique using self-made equipment. The CS-SA-EC film had superior mechanical properties compared to CS-EC and SA-EC films. The existence of the amide bond was confirmed by FT-IR. DSC confirmed that the drug was dispersed in the carrier material in an amorphous form. The drug release studies emerged that the model drugs from CS-SA-EC films presented better release properties. The Ritger-Peppas model best describes all ratios of drugs release mechanisms. The permeability characteristics of the films were evaluated in the TR146 cells model and the rabbit buccal mucosae. The cumulative penetration amounts of the model drugs were significantly increased. The permeability mechanism of the film was studied preliminarily using immunofluorescence and Western Blot. The results showed that the film inhibited the expression of ZO-1 protein, and the expressive trend of ZO-1 protein was consistent with the results of in vitro permeation experiments. The pharmacokinetics of the drugs loaded films were evaluated and compared with oral administration in rats. The relative bioavailability of the model drugs was 246.00% (Zolmitriptan) and 142.12% (Etodolac) relative to oral administration. The results of this study demonstrate the potential of CS-SA-EC vehicle in buccal mucosa drug delivery.

Improvement of the Antimicrobial Activity of Oregano Oil by Encapsulation in Chitosan-Alginate Nanoparticles

Oregano oil (OrO) possesses well-pronounced antimicrobial properties but its application is limited due to low water solubility and possible instability. The aim of this study was to evaluate the possibility to incorporate OrO in an aqueous dispersion of chitosan—alginate nanoparticles and how this will affect its antimicrobial activity. The encapsulation of OrO was performed by emulsification and consequent electrostatic gelation of both polysaccharides. OrO-loaded nanoparticles (OrO-NP) have small size (320 nm) and negative charge (−25 mV). The data from FTIR spectroscopy and XRD analyses reveal successful encapsulation of the oil into the nanoparticles. The results of thermogravimetry suggest improved thermal stability of the encapsulated oil. The minimal inhibitory concentrations of OrO-NP determined on a panel of Gram-positive and Gram-negative pathogens (ISO 20776-1:2006) are 4–32-fold lower than those of OrO. OrO-NP inhibit the respiratory activity of the bacteria (MTT assay) to a lower extent than OrO; however, the minimal bactericidal concentrations still remain significantly lower. OrO-NP exhibit significantly lower in vitro cytotoxicity than pure OrO on the HaCaT cell line as determined by ISO 10993-5:2009. The irritation test (ISO 10993-10) shows no signs of irritation or edema on the application site. In conclusion, the nanodelivery system of oregano oil possesses strong antimicrobial activity and is promising for development of food additives.

Study of Antibacterial and Anticancer Properties of bioAgNPs Synthesized Using Streptomyces sp. PBD-311B and the Application of bioAgNP-CNC/Alg as an Antibacterial Hydrogel Film against P. aeruginosa USM-AR2 and MRSA

Here, we report the extracellular biosynthesis of silver nanoparticles (AgNPs) and determination of their antibacterial and anticancer properties. We also explore the efficacy of bioAgNPs incorporated in cellulose nanocrystals (CNCs) and alginate (Alg) for the formation of an antibacterial hydrogel film. Streptomyces sp. PBD-311B was used for the biosynthesis of AgNPs. The synthesized bioAgNPs were characterized using UV-Vis spectroscopy, TEM, XRD, and FTIR analysis. Then, the bioAgNPs’ antibacterial and anticancer properties were determined using TEMA and cytotoxicity analysis. To form the antibacterial hydrogel film, bioAgNPs were mixed with a CNC and Alg solution and further characterized using FTIR analysis and a disc diffusion test. The average size of the synthesized bioAgNPs is around 69 ± 2 nm with a spherical shape. XRD analysis confirmed the formation of silver nanocrystals. FTIR analysis showed the presence of protein capping at the bioAgNP surface and could be attributed to the extracellular protein binding to bioAgNPs. The MIC value of bioAgNPs against P. aeruginosa USM-AR2 and MRSA was 6.25 mg/mL and 3.13 mg/mL, respectively. In addition, the bioAgNPs displayed cytotoxicity effects against cancer cells (DBTRG-0.5MG and MCF-7) and showed minimal effects against normal cells (SVG-p12 and MCF-10A), conferring selective toxicity. Interestingly, the bioAgNPs still exhibited inhibition activity when incorporated into CNC/Alg, which implies that the hydrogel film has antibacterial properties. It was also found that bioAgNP-CNC/Alg displayed a minimal or slow release of bioAgNPs owing to the intermolecular interaction and the hydrogel’s properties. Overall, bioAgNP-CNC/Alg is a promising antibacterial hydrogel film that showed inhibition against the pathogenic bacteria P. aeruginosa and MRSA and its application can be further evaluated for the inhibition of cancer cells. It showed benefits for surgical resection of a tumor to avoid post-operative wound infection and tumor recurrence at the surgical site.

Synergistic effect of the activated carbon addition from leather wastes in chitosan/alginate-based composites

In this work, chitosan/alginate composites were developed by the gelation method with the addition of different amounts of activated carbon produced from tannery waste (ACTW). The performance of these composites was verified through the adsorption of the textile dye Remazol Brilliant Blue R (RBBR). A synergistic effect was observed by the addition of ACTW; with a specific surface area up to 45.584 m²/g, the maximum adsorption capacity was 300.96 mg/g. The synergy was due to the reduction in steric hindrance, with the adsorption capacity 1.2 times higher than expected. The material was regenerated with sodium hydroxide for 10 cycles. The composite containing 30% ACTW (AC30) was applied in the treatment of real textile effluent, with 30% reductions in the biochemical oxygen demand (BOD), 39% in the chemical oxygen demand (COD), 78% in turbidity, and 67% in color.

Epoxy Cross-Linking Enhanced the Toughness of Polysaccharides as a Silicon Anode Binder for Lithium-Ion Batteries

The large volume expansion of a silicon anode induces serious mechanical failure and limits its applications. Owing to the intrinsic weak van der Waals force and poor toughness, it is unable to solve this issue with the current commercial poly(vinylidene difluoride) (PVDF) binder. The development of a binder with strong binding strength with silicon (Si) is urgent. Herein, a hydroxyl-rich three-dimensional (3D) network binder is synthesized by chemical cross-linking reactions between epichlorohydrin (ECH) and sodium hyaluronate (SH), which exhibits dramatically enhanced toughness and cohesive properties. The Si anode with the novel SH-ECH as the binder delivers excellent electrochemical performance, especially cycling stability. The discharge capacity could maintain 800.4 mAh g^-1 after 1000 cycles at a current of 0.2 C with the average capacity decay rate per cycle of 0.015%. Our results pave a new way for the tailoring of the chemical structures of natural polymers to realize lithium-ion batteries (LIBs) with superior electrochemical performance.

Silver-containing polysaccharide-based tricomponent antibacterial fibres for wound care applications

OBJECTIVE

Polysaccharide-based biomaterials are extensively used in wound care healing due to their unique liquid absorption, gelling properties and biocompatibility properties. They play an important role in controlling infections of highly exuding hard-to-heal wounds. The main objective of this study was to develop silver-containing polysaccharide-based tricomponent antibacterial fibres for use in these complex wounds.

METHOD

The fibres were developed by coating silver-containing alginate and psyllium fibres with hydrolysed chitosan. Dope solution containing alginate, psyllium and silver carbonate was extruded into a coagulation bath containing calcium chloride and hydrolysed chitosan. The developed fibres were tested for liquid absorption, swelling and antibacterial properties against a control fibre (of alginate and psyllium).

RESULTS

The developed fibres showed comparatively better liquid absorption, gelling and antibacterial properties than the control fibres.

CONCLUSION

The study concluded that developed fibres could be a preferred choice for application on hard-to-heal wounds with high levels of exudate, to support infection control and faster healing.

Novel synthesis of natural cation exchange resin by crosslinking the sodium alginate as a natural polymer with 1,6-hexamethylene diisocyanate in inert solvents: Characteristics and applications

Novel synthesis of natural polymeric cation exchanger from sodium alginate reagent as natural polymer (CAlg-Na)_n has been developed. This procedure takes place by crosslinking the solid sodium alginate with 1,6-hexamethylene diisocyanate (HDI) in dryness benzene as inert solvent (DB). The experimental results for crosslinking the alginate using different degrees of crosslinking of HDI/DB (w/w) showed that the capacity of the synthesized resin for binding the polyvalent metal ions reached its maximum at 30% of (HDI/D) ratio. This work aims to present a novel synthesis of cation exchange resin from natural polymers as an alternative promising competitor of low-cost, high performance and non-toxicity for removal of the toxic heavy metal ions in wastewater remediation and radionuclide pollutants from environmental contaminated media. The results obtained from various applied techniques for determining the bounded metal ion concentrations with (CAlg-Na)_n indicated that the resin capacity was followed the order U(VI) > Cu(II) > Sr(II) > Ca(II) at 25 °C, respectively. The factors influenced the alginate affinity for chelating the metal ions were explained in some correlation terms between the alginate capacity and some physicochemical properties of chelated metal ions and its respective formed complexes. Speculated geometrical configurations for chelation were suggested and discussed.

Hybrid Methacrylated Gelatin and Hyaluronic Acid Hydrogel Scaffolds. Preparation and Systematic Characterization for Prospective Tissue Engineering Applications

Hyaluronic acid (HA) and gelatin (Gel) are major components of the extracellular matrix of different tissues, and thus are largely appealing for the construction of hybrid hydrogels to combine the favorable characteristics of each biopolymer, such as the gel adhesiveness of Gel and the better mechanical strength of HA, respectively. However, despite previous studies conducted so far, the relationship between composition and scaffold structure and physico-chemical properties has not been completely and systematically established. In this work, pure and hybrid hydrogels of methacroyl-modified HA (HAMA) and Gel (GelMA) were prepared by UV photopolymerization and an extensive characterization was done to elucidate such correlations. Methacrylation degrees of ca. 40% and 11% for GelMA and HAMA, respectively, were obtained, which allows to improve the hydrogels’ mechanical properties. Hybrid GelMA/HAMA hydrogels were stiffer, with elastic modulus up to ca. 30 kPa, and porous (up to 91%) compared with pure GelMA ones at similar GelMA concentrations thanks to the interaction between HAMA and GelMA chains in the polymeric matrix. The progressive presence of HAMA gave rise to scaffolds with more disorganized, stiffer, and less porous structures owing to the net increase of mass in the hydrogel compositions. HAMA also made hybrid hydrogels more swellable and resistant to collagenase biodegradation. Hence, the suitable choice of polymeric composition allows to regulate the hydrogels´ physical properties to look for the most optimal characteristics required for the intended tissue engineering application.

Rheology and Water Absorption Properties of Alginate-Soy Protein Composites

Composite materials based on proteins and carbohydrates normally offer improved water solubility, biodegradability, and biocompatibility, which make them attractive for a wide range of applications. Soy protein isolate (SPI) has shown superabsorbent properties that are useful in fields such as agriculture. Alginate salts (ALG) are linear anionic polysaccharides obtained at a low cost from brown algae, displaying a good enough biocompatibility to be considered for medical applications. As alginates are quite hydrophilic, the exchange of ions from guluronic acid present in its molecular structure with divalent cations, particularly Ca2+, may induce its gelation, which would inhibit its solubilization in water. Both biopolymers SPI and ALG were used to produce composites through injection moulding using glycerol (Gly) as a plasticizer. Different biopolymer/plasticizer ratios were employed, and the SPI/ALG ratio within the biopolymer fraction was also varied. Furthermore, composites were immersed in different CaCl2 solutions to inhibit the amount of soluble matter loss and to enhance the mechanical properties of the resulting porous matrices. The main goal of the present work was the development and characterization of green porous matrices with inhibited solubility thanks to the gelation of alginate.

Development of bioactive sodium alginate/sulfonated polyether ether ketone/hydroxyapatite nanocomposites: Synthesis and in-vitro studies

Developing bioactive composites to fill bone cavities caused by disease, injury or surgery still remains a challenge. The aim of this research was to develop a new nanostructured sodium alginate/sulfonated polyether ether ketone/nano-hydroxyapatite (Alg/SPEEK/HA) biocomposite via a simple chemical precipitation strategy. Structural analysis was carried out using X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) was used to compare the HA content of the composites. The in-vitro bioactivity of the composites with different content of HA was investigated by immersing the specimens in the simulated body fluid (SBF) for 15 days. The presence of HA in the composite structure gave rise to the precipitation of an apatite layer on the surface, which was increased by increase in the content of HA. The formation of the HA layer on the composite surface was scrutinized via FESEM and EDX analysis. Transmission electron microscopy (TEM) images exhibited the presence of HA nanoparticles with less than 30 nm in size. The in-vitro cytotoxicity evaluation was also carried out using MG-63 cells via the MTT assay, which revealed that the cytocompatibility of all specimens was increased with raising the HA content. However, the higher concentration (100 μg/ml) of the composites displayed some toxicity against MG-63 cells. These findings, therefore, proposed that the achieved novel nanocomposites could be regarded as promising materials to serve as bone filler.

Thermal Properties and Structural Features of Multilayer Films Based on Chitosan and Anionic Polysaccharides

This study investigates the thermal and structural properties of multilayer composites based on chitosan (CS) and polyanions with different functionalities, including sodium sulfoethyl cellulose (SEC), sodium alginate (ALG), and sodium hyaluronate (HA). Unlike polyelectrolyte complexes (PECs) obtained by polymer mixing, the formation of a PEC layer by a process of layer-by-layer deposition of oppositely charged polymers is accompanied by the transformation of the CS polymorphic state, and this affects the relaxation and thermal properties of the resulting multilayer composite. X-ray diffraction analysis showed that the formation of the PEC layer in the CS/SEC multilayer film is accompanied by crystallization of the CS chains and the formation of a predominantly anhydrous CS modification. Thermogravimetric analysis of the CS/SEC film registers a high-temperature peak associated with the thermal decomposition of crystalline CS in the PEC composition. According to the dynamic mechanical analysis, the CS/SEC composite was characterized by a single glass transition temperature, indicating a strong interaction between the layers when using SEC (a strong acid salt) as the counterion to CS. For multilayer composites with weak polyacid salts (ALG and HA), the crystallization of CS in the PEC layer is weaker, as reflected in the thermal degradation of these films. A high-temperature peak is recorded in the thermal decomposition of CS/HA and is absent in the case of CS/ALG. Dynamic mechanical analysis of the CS/ALG composite showed two glass transition temperatures close to those of the original polymers, indicating weak PEC formation. The CS/HA composite showed an intermediate response. Thus, the effect of the PEC layer on the properties of the poly-layer composites decreases in the order CS/SEC > CS/HA > CS/ALG.

Chitosan and glyceryl monooleate nanostructures containing gallic acid isolated from amla fruit: targeted delivery system

Gallic acid, active constituent of amla fruit its natural abundance with beneficial multi actions in body make them attractive for clinical applications. In present study, we focused on extracting, separating and characterizing gallic acid from amla and further formulated into chitosan nanoparticles, so bring it to increase its aqueous solubility and thereby bioactivity. Gallic acid nanoparticles were prepared by using poloxamer 407, chitosan and Glyceryl Monooleate (GMO) using probe sonicator and high pressure homogenization method. Prepared nanoparticles were characterized by particle size, zeta potential, DSC, XRD, SEM, entrapment efficiency, loading content, in-vitro release and stability study. They showed approximately 76.80% encapsulation of gallic acid with average size of 180.8 ± 0.21 nm, and zeta potential +24.2 mV. The cumulative in vitro drug release upto 24 hrs 77.16% was achieved suggesting that from all our findings, it can be concluded that work will facilitate extraction, design and fabrication of nanoparticles for protection and sustained release of gallic acid particularly to colonic region.

Examining the Impact of Squaric Acid as a Crosslinking Agent on the Properties of Chitosan-Based Films

Hydrogels based on chitosan are very versatile materials which can be used for tissue engineering as well as in controlled drug delivery systems. One of the methods for obtaining a chitosan-based hydrogel is crosslinking by applying different components. The objective of the present study was to obtain a series of new crosslinked chitosan-based films by means of solvent casting method. Squaric acid-3,4-dihydroxy-3-cyclobutene-1,2-dione-was used as a safe crosslinking agent. The effect of the squaric acid on the structural, mechanical, thermal, and swelling properties of the formed films was determined. It was established that the addition of the squaric acid significantly improved Young's modulus, tensile strength, and thermal stability of the obtained materials. Moreover, it should be stressed that the samples consisting of chitosan and squaric acid were characterized by a higher swelling than pure chitosan. The detailed characterization proved that squaric acid could be used as a new effective crosslinking agent.

The Study of Plasticized Sodium Ion Conducting Polymer Blend Electrolyte Membranes Based on Chitosan/Dextran Biopolymers: Ion Transport, Structural, Morphological and Potential Stability

The polymer electrolyte system of chitosan/dextran-NaTf with various glycerol concentrations is prepared in this study. The electrical impedance spectroscopy (EIS) study shows that the addition of glycerol increases the ionic conductivity of the electrolyte at room temperature. The highest conducting plasticized electrolyte shows the maximum DC ionic conductivity of 6.10 × 10⁻⁵ S/cm. Field emission scanning electron microscopy (FESEM) is used to investigate the effect of plasticizer on film morphology. The interaction between the electrolyte components is confirmed from the existence of the O–H, C–H, carboxamide, and amine groups. The XRD study is used to determine the degree of crystallinity. The transport parameters of number density (n), ionic mobility (µ), and diffusion coefficient (D) of ions are determined using the percentage of free ions, due to the asymmetric vibration (υ_as(SO₃)) and symmetric vibration (υ_s(SO₃)) bands. The dielectric property and relaxation time are proved the non-Debye behavior of the electrolyte system. This behavior model is further verified by the existence of the incomplete semicircle arc from the Argand plot. Transference numbers of ion (t_ion) and electron (t_e) for the highest conducting plasticized electrolyte are identified to be 0.988 and 0.012, respectively, confirming that the ions are the dominant charge carriers. The t_ion value are used to further examine the contribution of ions in the values of the diffusion coefficient and mobility of ions. Linear sweep voltammetry (LSV) shows the potential window for the electrolyte is 2.55 V, indicating it to be a promising electrolyte for application in electrochemical energy storage devices.

One-step synthesis of composite hydrogel capsules to support liver organoid generation from hiPSCs

Advances in biomaterials, especially in hydrogels, have offered great opportunities for stem cell organoid engineering with higher controllability and fidelity. Here, we propose a novel strategy for one-step synthesis of composite hydrogel capsules (CHCs) that enable engineering liver organoids from human induced pluripotent stem cells (hiPSCs) in an oil-free droplet microfluidic system. The CHCs composed of a fibrin hydrogel core and an alginate-chitosan composite shell are synthesized by an enzymatic crosslinking reaction and electrostatic complexation within stable aqueous emulsions. The proposed CHCs exhibit high uniformity with biocompatibility, stability and high-throughput properties, as well as defined compositions. Moreover, the established system enables 3D culture, differentiation and self-organized formation of liver organoids in a continuous process by encapsulating hepatocyte-like cells derived from hiPSCs. The encapsulated liver organoids consisting of hepatocyte- and cholangiocyte-like cells show favorable cell viability and growth with consistent size. Furthermore, they maintain proper liver-specific functions including urea synthesis and albumin secretion, replicating the key features of the human liver. By combining stem cell biology, defined hydrogels and the droplet microfluidic technique, the proposed system is easy-to-operate, scalable and stable to engineer stem cell organoids, which may offer a robust platform to advance organoid research and translational applications.

Drawbacks of Low Lattice Energy Ammonium Salts for Ion-Conducting Polymer Electrolyte Preparation: Structural, Morphological and Electrical Characteristics of CS:PEO:NH4BF4-Based Polymer Blend Electrolytes

In the present work it was shown that low lattice energy ammonium salts are not favorable for polymer electrolyte preparation for electrochemical device applications. Polymer blend electrolytes based on chitosan:poly(ethylene oxide) (CS:PEO) incorporated with various amounts of low lattice energy NH4BF4ammonium salt have been prepared using the solution cast technique. Both structural and morphological studies were carried out to understand the phenomenon of ion association. Sharp peaks appeared in X-ray diffraction (XRD) spectra of the samples with high salt concentration. The degree of crystallinity increased from 8.52 to 65.84 as the salt concentration increased up to 40 wt.%. These are correlated to the leakage of the associated anions and cations of the salt to the surface of the polymer. The structural behaviors were further confirmed by morphological study. The morphological results revealed the large-sized protruded salts at high salt concentration. Based on lattice energy of salts, the phenomena of salt leakage were interpreted. Ammonium salts with lattice energy lower than 600 kJ/mol are not preferred for polymer electrolyte preparation due to the significant tendency of ion association among cations and anions. Electrical impedance spectroscopy was used to estimate the conductivity of the samples. It was found that the bulk resistance increased from 1.1 × 104 ohm to 0.7 × 105 ohm when the salt concentration raised from 20 wt.% to 40 wt.%, respectively; due to the association of cations and anions. The low value of direct current (DC) conductivity (7.93 × 10-7 S/cm) addressed the non-suitability of the electrolytes for electrochemical device applications. The calculated values of the capacitance over the interfaces of electrodes-electrolytes (C2) were found to drop from 1.32 × 10-6 F to 3.13 × 10-7 F with increasing salt concentration. The large values of dielectric constant at low frequencies are correlated to the electrode polarization phenomena while their decrements with rising frequency are attributed to the lag of ion polarization in respect of the fast orientation of the applied alternating current (AC) field. The imaginary part of the electric modulus shows obvious peaks known as conduction relaxation peaks.