Search Results (562)

Natural polysaccharides are used for very different applications and are particularly exploited for preparing hydrogel materials. For instance, gels based on different carbohydrate polymers have been applied to remove unwanted materials from the surface of cultural heritages items. This study was focused on the preparation of novel physical hydrogels suitable for the cleaning of sensitive materials like wood and paper, i.e., to remove the soil from their surface. For this purpose, alginate biopolymer was used and ionically crosslinked with six different amines, in the presence of N-hydroxysuccinimide as a co-gelling agent. All the synthetized gel materials were characterized by a multianalytical approach, using different techniques such as FT-IR, thermal analysis, SEM-EDS, mechanical tests, and evaluation of moisture properties. All the results showed that the introduction of the investigated amines improved the original properties of alginate and provided good cleaning properties when applied to sensitive surfaces. Full article

Using Microcystis aeruginosa as the raw material, the microalgae was modified through a potassium permanganate–ferrous sulfate treatment process to prepare Fe-Mn oxide-modified algal powder. Sodium alginate was then combined with this modified powder to create Fe-Mn-modified algal powder gel beads, which were employed for the adsorption of Cd(II) from water. At pH = 9, with dosage of 6 g·L⁻¹ and a contact time of 8 h, the Cd(II) solution at an initial level of 1.0 mg·L⁻¹ achieved a removal efficiency of 96%, and the maximum adsorption capacity is 15.06 mg·g⁻¹. The adsorption behavior conformed to the Langmuir isotherm and obeyed the pseudo-second-order kinetics, and was primarily governed by chemical adsorption. This involved complexation with hydroxyl (-OH) and carboxyl (-COO⁻) functional groups, the ion exchange of Ca²⁺ with Cd(II), and surface complexation on Fe-Mn oxides. This study provides a valuable basis for the resource utilization of algae and the remediation of Cd contamination. Full article

Alginate hydrogels are attractive for biomedical applications and drug delivery due to their biocompatibility and biodegradability. However, calcium-crosslinked alginates often exhibit only moderate absorption properties compared with synthetic hydrogels. This study examined how the form of calcium ion delivery affects the mechanical, swelling, and morphological characteristics of calcium-crosslinked alginate hydrogels. We prepared four alginate hydrogel samples in which Ca²⁺ was introduced on different polyacrylate polymer carriers, and a reference hydrogel crosslinked with calcium citrate. All samples were characterized by equilibrium swelling, gel fraction determination, and rheological frequency-sweep measurements. Also, the average mesh size was estimated using two independent theoretical approaches. Hydrogels prepared with calcium salt of polyacrylic acid (PAA) exhibited higher mechanical strength and higher water swelling than the citrate-crosslinked reference. Calculated mean mesh sizes for the citrate system ranged from 58 to 221 nm, whereas high-molecular-weight crosslinked systems showed a broader distribution (68–708 nm). These results demonstrate that the form of Ca²⁺ introduction significantly influences network architecture and functional properties and indicates that tuning the carrier form of calcium provides a practical route to design swelling, mesh size, and mechanical behavior of alginate-based hydrogels for specific biomedical or delivery applications. Full article

Incorporating cyclodextrins (CDs) into ionically crosslinked polysaccharide matrices offers a promising strategy for developing well-defined, safe-by-design and biocompatible carrier systems with tunable rheological properties. In this study, β-cyclodextrin (β-CD) was functionalized with citric acid (CDC) and maleic anhydride (CDM) using solvent-free synthesis to improve compatibility with alginate hydrogels. The modified CDs were characterized by FTIR, ¹H NMR, DLS, zeta potential, and MS, confirming successful esterification (4.0 and 3.4 –OH substitution for CDC and CDM, respectively) and stable aqueous dispersion. Rheological measurements showed that native CD accelerated gelation (within approximately 30 s), while CDC and CDM delayed crosslinking (by 2 to 13 min) and reduced gel strength, narrowing the linear viscoelastic range to 0.015–0.089% strain due to competition between polycarboxylated CDs and alginate chains for Ca²⁺ ions. Vibrational prilling produced alginate microbeads with diameters of 800–1000 µm and a simultaneous increase in size and CD concentration. Hydrogels demonstrated high CD retention (>80% after 28 h) and slightly greater release of CDC and CDM than native CD. Overall, solvent-free modification of CDs with citric and maleic acids provides a sustainable approach to tailoring the gelation kinetics, viscoelasticity, and release behavior of alginate-based hydrogels, offering a versatile, food- and health-compliant platform for controlled delivery of bioactive compounds. Full article

Bio-based photo-crosslinkable hydrogels are used in tissue engineering as three-dimensional printable scaffolds due to their functional and biological similarities with the extracellular matrix (ECM). In this work, emerging bioink candidates such as chitosan, alginate and gelatin-based photo-crosslinkable hydrogel were developed using extrusion-based 3D printing to establish a better understanding of their applicability. The polymers were methacrylated by the same methacrylation reaction pathway, which enabled successful light-induced 3D printing. Morphology, swelling (6–40%), mechanical (Young’s modulus, 0.1–0.5 KPa) and rheological properties (300–1000 Pa), degradation kinetics (10->60 days) and printability of the gels were also characterized in identical conditions for the first time. 3D-printability results indicated that methacrylated gelatin enhanced printability, shape fidelity and integrity of printed structures compared to methacrylated alginate, which presents structural instability and poorer printing control due to its low crosslink density. Moreover, cell attachment and Live/Dead assays using bone marrow-derived mesenchymal stem cells (BM-MSCs) showed that all formulations have good biocompatibility for use as scaffolds. Specifically, gelatin-based hydrogels showed a higher level of BM-MSCs attachment and spreading than the other types of hydrogels. Overall, our results suggest that the hydrogels based on these three biopolymers present good potential as a biomaterial for light-induced extrusion-based 3D printing. Full article

This article presents the results of a study on the rheological characteristics of in situ thermosensitive nasal gels based on poloxamer 407 (P407) and their effect on spray angle. The development of new drug delivery systems based on in situ thermosensitive gels can overcome several shortcomings of traditional nasal sprays associated with mucociliary clearance and low mucoadhesion. Using the cold method, samples based on P407 were prepared in pure form, in combination with poloxamer 188 (P188), and with the addition of several mucoadhesive polymers: chitosan, sodium alginate, and hydroxypropyl methylcellulose (HPMC). Analytical studies were carried out for all obtained samples, which showed that the gelling temperature (T_sol–gel) of compositions with P407 was inversely dependent on its concentration, decreasing from 32.71 °C to 24.63 °C. The addition of hydrophilic P188 increased T_sol–gel. The addition of mucoadhesive polymers had varying effects on T_sol–gel: chitosan and HPMC increased the temperature, while sodium alginate decreased it. The addition of mucoadhesive polymers significantly affected the viscosity of the formulations; for example, the addition of sodium alginate resulted in a fivefold increase, making the formulations unsuitable for spraying. A study of the spray angles of T_sol–gel samples in the range of 27–31 °C using the SprayVIEW measuring system revealed an inverse relationship between the viscosity of the formulations and the spray angle. A mathematical model of the solution droplet trajectory was presented, enabling the spray angle to be predicted depending on the formulation composition. The relative error of the computational experiments did not exceed 10%. This approach has the potential to reduce the number of full-scale experiments, and consequently their cost. Full article

The effect of varying sodium alginate (SA) concentrations (1%, 2%, and 3%; SA1–SA3) on the encapsulation of tangerine (Citrus reticulata Blanco ‘Cho Khun’) peel extract (TPE, 0.5% w/v) into hydrogel beads was evaluated. Overall, the results showed that increasing SA concentration significantly altered bead characteristics: lightness (L*) decreased from 56.35 to 45.57, red-green axis (a*) shifted negatively from −1.32 to −6.87, and yellow-blue axis (b*) increased from −17.81 to 6.41. Moisture content (97.85% to 93.16%) and water activity (0.96 to 0.93) declined with higher SA, while hardness increased (4.12 to 5.17 g). ζ-potential values shifted from −29.10 mV (SA1) to −39.10 mV (SA3), confirming enhanced electrostatic stabilization. FTIR spectra revealed characteristic alginate functional groups, and morphological analysis showed smoother, denser beads at higher SA concentrations. Phenolic (47.86–48.51 mg GAE g⁻¹ DW) and flavonoid (34.02–36.68 mg QE g⁻¹ DW) contents were well-retained, supporting antioxidant activities (DPPH 70.34–72.54%; ABTS 65.66–66.91%). Antimicrobial tests demonstrated > 4-log reductions against E. coli and P. aeruginosa. Sensory evaluation revealed that higher SA concentrations improved texture and taste. Overall, SA encapsulation, particularly at 3%, effectively stabilized TPE, preserving its functional properties for potential food and nutraceutical applications. Full article

The increasing demand for sustainable agriculture has accelerated research into eco-friendly plant health management, particularly through natural substances rich in bioactive compounds. In this study, various substances, including essential oils, extracts from Aloe vera, artichoke and ornamental plants, by-products from beer and coffee processing, and selected commercial formulations including biostimulants and a plant strengthener, were evaluated for their antimicrobial properties and ability to trigger plant defenses. Notably, Agapanthus spp. exhibited strong antifungal activity against the fungus Botrytis cinerea (Bc), while thyme, tea tree, and lavender essential oils were effective against both Bc and the bacterium Pseudomonas syringae pv. tomato (Pst). Greenhouse trials on tomato plants demonstrated the protective effects of A. vera gel and ornamental plant extracts against Bc and Potato virus Y (PVY), while coffee and artichoke extracts were effective against Pst. An alginate-based formulation containing thyme oil showed enhanced in planta efficacy against the three pathogens. Gene expression analyses revealed early upregulation of PR-1 and PR-4, especially with alginate treatments and A. vera gel at 12 h post-treatment (hpt) while coffee extract triggered the strongest late response at 72 hpt. These findings highlight the potential of plant-derived substances in promoting sustainable plant disease management through both direct antimicrobial action and immune system activation. Full article

This study presents the development of an advanced three-dimensional (3D) bioprinted skin scaffold integrating sodium alginate (SA), gelatin (Gel), human skin-derived decellularized extracellular matrix (dECM), and microbiota-derived postbiotics. To ensure a biocompatible and functional ECM source, human skin samples collected during elective aesthetic surgical procedures were utilized. Following enzymatic treatment, the dermal layer was carefully separated from the epidermis and subjected to four different decellularization protocols. Among them, Protocol IV emerged as the most suitable, achieving significant DNA removal while maintaining the structural and biochemical integrity of the ECM, as confirmed by Fourier-transform infrared spectroscopy. Building on this optimized dECM-4, microbiota-derived postbiotics from Limosilactobacillus reuteri EIR/Spx-2 were incorporated to further enhance the scaffold’s bioactivity. Hybrid scaffolds were then fabricated using 7% Gel, 2% SA, 1% dECM-4, and 40 mg/mL postbiotics in five-layered grid structures via 3D bioprinting technology. Although this composition resulted in reduced mechanical strength, it exhibited improved hydrophilicity and biodegradability. Moreover, antimicrobial assays demonstrated inhibition zones of 16 mm and 13 mm against methicillin-resistant Staphylococcus aureus (MRSA, ATCC 43300) and Pseudomonas aeruginosa (ATCC 27853), respectively. Importantly, biocompatibility was confirmed through in vitro studies using human keratinocyte (HaCaT) cells, which adhered, proliferated, and maintained normal morphology over a 7-day culture period. Taken together, these findings suggest that the engineered hybrid scaffold provides both regenerative support and antimicrobial protection, making it a strong candidate for clinical applications, particularly in the management of chronic wounds. Full article

Fungal mycelial pellets (MPs) exhibit high biomass-loading capacity; however, their application in wastewater treatment is constrained by structural fragility and the risk of environmental dispersion. To overcome these limitations, a dual-crosslinked polyvinyl alcohol–alginate gel (10% PVA, 2% sodium alginate) embedding strategy was developed and stabilized using 2% CaCl₂ and saturated boric acid. This encapsulation enhanced the tensile strength of MPs by 499% (310.4 vs. 62.1 kPa) and improved their settling velocity by 2.3-fold (1.12 vs. 0.49 cm/s), which was critical for stability under turbulent bioreactor conditions. Following encapsulation, the specific oxygen uptake rates (SOURs) of three fungal strains (F557, Y3, and F507) decreased by 30.3%, 54.8%, and 48.3%, respectively, while maintaining metabolic functionality. SEM revealed tight adhesion between the gel layer and both surface and internal hyphae, with the preservation of porous channels conducive to microbial colonization. In sequential-batch reactors treating sulfamethoxazole (SMX)-contaminated wastewater, gel-encapsulated MPs combined with acclimated sludge consistently achieved 72–75% SMX removal efficiency over six cycles, outperforming uncoated MPs (efficiency decreased from 81.2% to 58.7%) and pure gel–sludge composites (34–39%). The gel coating inhibited hyphal dispersion by over 90% and resisted mechanical disintegration under 24 h agitation. This approach offers a scalable and environmentally sustainable means of enhancing MPs’ operational stability in continuous-flow systems while mitigating fungal dissemination risks. Full article

Edible hydrogels are the central material class in 3D food printing because they reconcile two competing needs: (i) low resistance to flow under nozzle shear and (ii) fast recovery of elastic structure after deposition to preserve geometry. This review consolidates the recent years of progress on hydrogel formulations—gelatin, alginate, pectin, carrageenan, agar, starch-based gels, gellan, and cellulose derivatives, xanthan/konjac blends, protein–polysaccharide composites, and emulsion gels alongside a critical analysis of printing technologies relevant to food: extrusion, inkjet, binder jetting, and laser-based approaches. For each material, this review connects gelation triggers and compositional variables to rheology signatures that govern printability and then maps these to process windows and post-processing routes. This review consolidates a decision-oriented workflow for edible-hydrogel printability that links formulation variables, process parameters, and geometric fidelity through standardized test constructs (single line, bridge, thin wall) and rheology-anchored gates (e.g., yield stress and recovery). Building on these elements, a “printability map/window” is formalized to position inks within actionable operating regions, enabling recipe screening and process transfer. Compared with prior reviews, the emphasis is on decisions: what to measure, how to interpret it, and how to adjust inks and post-set enablers to meet target fidelity and texture. Reporting minima and a stability checklist are identified to close the loop from design to shelf. Full article

Hydrogels with protein–polysaccharide combinations are widely used in the field of tissue engineering, as they can mimic the in vivo environments of native tissues, specifically the extracellular matrix (ECM). However, achieving stability and mechanical properties comparable to those of tissues by employing natural polymers remains a challenge due to their weak structural characteristics. In this work, we optimized the fabrication strategy of a hydrogel composite, comprising gelatin and sodium alginate (Gel-SA), by varying reaction parameters. Magnetite (Fe₃O₄) nanoparticles were incorporated to enhance the mechanical stability and structural integrity of the scaffold. The changes in hydrogel stiffness and viscoelastic properties due to variations in polymer mixing ratio, crosslinking time, and heating cycle, both before and after nanoparticle incorporation, were compared. FTIR spectra of crosslinked hydrogels confirmed physical interactions of Gel-SA, metal coordination bonds of alginate with Ca²⁺, and magnetite nanoparticles. Tensile and rheology tests confirmed that even at low magnetite concentration, the Gel-SA-Fe₃O₄ hydrogel exhibits mechanical properties comparable to soft tissues. This work has demonstrated enhanced resilience of magnetite-incorporated Gel-SA hydrogels during the heating cycle, compared to Gel-SA gel, as thermal stability is a significant concern for hydrogels containing gelatin. The interactions of thermoreversible gelatin, anionic alginate, and nanoparticles result in dynamic hydrogels, facilitating their use as viscoelastic acellular matrices. Full article

Gastroesophageal reflux disease (GERD) is associated with symptoms such as heartburn, resulting from gastric content reflux. Alginate-based raft-forming gel formulations represent a non-pharmacological strategy for GERD management by forming a floating gel barrier in the stomach. This study evaluated three commercial anti-reflux oral gel systems under simulated fed-state gastric conditions, using in vitro magnetic resonance relaxometry techniques. Magnetic resonance imaging (MRI) was performed in 0.01 M hydrochloric acid (HCl) to visualize gel raft formation, spatial structure, and spatial distribution of effective T₂ relaxation time. Nuclear magnetic resonance (NMR) relaxometry in 0.01 M deuterium chloride (DCl) measured T₁ and T₂ relaxation times of the protons that were initially included in the preparation to assess its molecular mobility within the gel matrix. Two formulations formed floating, coherent gels, whereas the remaining one exhibited only polymer swelling without flotation. In one case, relaxometry data revealed a solid-like component that can be detected, indicating enhanced mechanical stability. The performance of each formulation was influenced by interactions among alginate, bicarbonates, and calcium ions, which determined gel consistency and flotation behavior. MRI and NMR relaxometry in vitro provide valuable non-invasive insights into the structural and functional behavior of alginate-based gel formulations. This approach supports the rational design of advanced gel-based therapies for GERD by linking molecular composition with in situ performance. Full article

In this study, the effect of cationic participation on the swelling behavior and pH-responsive release characteristics of polyelectrolyte hydrogel based on gelatin (Gel), sodium alginate (Alg), and carboxymethyl chitosan (CMCS) was explored. The shell–core morphology of the cationic coordination hydrogels was prepared by introducing Na⁺, Ca²⁺, and Fe³⁺ into the crosslinking system, which significantly altered the inherent pH-responsive swelling properties of Gel/Alg-CMCS hydrogel. The modified hydrogel demonstrated a release resistance of carvacrol (CAR) under acidic conditions while facilitating rapid release under neutral conditions. Notably, the CAR release profile was substantially modified by the distinct anti-swelling properties of cationic coordination hydrogels. In particular, Gel/Alg-CMCS-Fe³⁺ hydrogel exhibited high accumulative release of 58.34% at pH 1.0 while maintaining a minimal release degree of merely 7% in weakly acidic and neutral environments. These intriguing findings provide valuable insights into intelligent active delivery for future applications. Full article

Biofumigation was originally proposed as an alternative to toxic fumigants for the treatment of agricultural soils, owing to the biocidal effect of isothiocyanates (ITCs) released by some plant species like Brassicaceae. However, biofumigation also presents limitations; thus, an advanced and viable alternative could be the use of controlled-release systems such as gelled polymer networks. In the present work, we explore the use of biocompatible hydrogels based on sodium alginate (ALG) and sodium carboxymethylcellulose (CMC), conveniently loaded with a Brassicaceae extract for this purpose. The extract was characterized by means of HPLC-MS, showing its high glucosinolate content, especially glucoraphanin, a secondary metabolite produced by several species of this family. The physicochemical properties of the synthesized gels were investigated by means of differential scanning calorimetry (DSC), rheometry, and scanning electron microscopy (SEM), both in the presence and absence of the loaded extract. Loading and release kinetics (in water) were studied by means of HPLC-DAD, and the Weibull model was employed to interpret the results. It was found that both hydrogels can effectively confine the Brassicaceae extract’s active principle, slowly releasing it in an aqueous environment. Both systems possess excellent properties for real applications, with the CMC-based hydrogels being slightly preferable over the ALG ones due to their higher encapsulation efficiency, mechanical properties, and overall features. These systems are promising tools for combating harmful microorganisms due to the biocidal properties of glucosinolates, but their potential goes beyond their use in agriculture, as they could be applied as antifouling or antimicrobial agents in cultural heritage cleaning or other fields. Full article