Search Results (136)

Marine polymers have attracted a lot of attention as potential alternatives to the traditional animal-derived polymers in pharmaceutical formulation since they are abundant, biocompatible, and versatile in functionality. However, the presence of these materials in dosage-form studies, often in support of proof-of-concept trials, does not mean they are ready to apply as excipients routinely. This review critically evaluates the reasons why three of the most highly researched marine-derived polymers, chitosan, alginate, and carrageenan, continue to encounter significant translational barriers in pharmaceutical excipient development. All three polymers have been demonstrated to have clear pharmaceutical utility; however, their behavior is highly dependent on source, structure, processing history and formulation context. Chitosan explains why functional benefits may be compromised by responses to material requirements; alginate explains why apparent proximity to use may not remove composition-related variability; and carrageenan explains that even seemingly simple rheological functions may be very context-dependent. All of this points to the fact that the major hurdle lies not in the lack of potential, but in the difficulty of achieving the required degree of control, reproducibility, and manufacturability in order to make the reliable use of excipients possible. Future progress in this field will likely require a shift from descriptive exploration toward readiness-focused evidence, including demonstrated control over material attributes, reproducible performance, and feasible qualification pathways. Full article

Background/Objectives: Seasonal waves of respiratory viruses—including SARS-CoV-2, influenza A virus (IAV), and respiratory syncytial virus (RSV)—continue to pose a global health burden and highlight the need for antiviral agents that are effective, safe, broadly active, affordable, and widely accessible. Current interventions are limited by the need for their early administration, the risk of resistance, their costs, and the restricted availability in large parts of the world. For certain natural products, such as European black elderberry (Sambucus nigra L.) fruit extract (ElderCraft^®; EC) and the seaweed-derived sulfated polymer iota-carrageenan (IC), antiviral activities against respiratory viruses, particularly IAV and SARS-CoV-2, have previously been shown. Here, we assessed the antiviral activity of IC and an anthocyanin-standardized EC extract against SARS-CoV-2, IAV, and RSV, either as monotherapy or in multiple-dose combinations. Methods: MDCKII cells were infected with IAV_PR8, human Calu-3 lung epithelial cells with the SARS-CoV-2 Omicron variant, and HEp-2 cells with RSV (A2 strain). Inhibitors were administered either by pre-incubation of cell-free virions prior to infection or, in separate time-of-addition experiments, during or post-infection. Viral replication was quantified by qRT-PCR or intracellular immunostaining. Cytotoxicity was evaluated using a neutral red uptake assay. Results: Most intriguingly, both EC and IC are able to neutralize virions derived from SARS-CoV-2, IAV, or RSV extracellularly in a dose-dependent manner. Notably, EC and IC alone exhibited strong anti-RSV activity, which was not reported previously. Most importantly, combined treatment with IC and EC caused a pronounced synergistic antiviral effect against the tested viruses, as confirmed by the Bliss independence model, without any detectable impact on cell viability. Finally, solutions prepared from matrix-standardized mono- or combi-lozenges, containing IC and/or EC in high or low doses, reproduced the antiviral and synergistic combination effects observed with the pure compounds. Conclusions: In summary, these findings support further development of EC and IC as a topically accessible, virion-neutralizing combination (e.g., lozenges) to provide additional protection against major respiratory viruses and potentially strengthen pandemic preparedness. Full article

In the current study, bioactive-loaded hydrogels were developed with k-carrageenan (1%), and water was replaced with infusions of Urtica dioica L., which modulated the polymer chains to create more robust networks. Urtica dioica L. infusions were obtained with different infusion durations (5 or 10 min) or plant-to-water ratios (0.4, 1, or 2 g/100 mL). The hydrogels were characterized for stability by assessing the syneresis rate and textural and rheological attributes. To elucidate the influence of the infusion on the mechanisms of k-carragenan, temperature ramp tests were applied and FTIR spectra were acquired. Replacing water with Urtica dioica L. infusions for obtaining k-carrageenan hydrogels led to lower syneresis rates (3.34 ± 0.03% and 6.67 ± 0.33%), while the hydrogels showed increased hardness, but lower resilience and cohesiveness. The rheological parameters confirmed the reinforcement; higher G′ and gelling temperatures were registered compared to the reference. While FTIR spectra showed that the primary chemical backbone remained intact, the physicochemical changes indicate a strong physical synergy between nettle polyphenols and the κ-carrageenan chains. Of all samples, the highest antioxidant potential value of 94.66% was exhibited by the infusion obtained in 15 min with a ratio of plant material of 2/100 g. These findings demonstrate that plant-to-water ratios and infusion times are critical parameters for tuning the physical properties and biological efficacy of hydrogels for medical or food applications. Full article

Curcumin exhibits potent anti-obesity and anti-inflammatory activities; however, its therapeutic application is limited by poor aqueous solubility and low oral bioavailability. A curcumin-loaded chewable gel was developed to transform into an in situ gastric gel upon contact with gastric fluid after mastication. Curcumin solid dispersions (CUR-SDs) were prepared with Eudragit^® EPO (1:1–1:7, w/w) using the solvent evaporation method. The optimized formulation (1:3) markedly enhanced solubility and dissolution in acidic medium (0.1 N HCl, pH 1.2) compared with crystalline curcumin and physical mixtures. The optimized CUR-SD was subsequently incorporated into chewable gels composed of sodium alginate and κ-carrageenan, with calcium carbonate as a gas-forming agent. The formulations formed buoyant matrices under acidic conditions, exhibiting floating lag times of 21–215 s and sustaining drug release for up to 8 h. Increasing polymer content improved mechanical strength and modulated release kinetics. Among the tested formulations, F7 achieved the optimal balance between texture properties, floating behavior, and controlled-release performance. In LPS-stimulated RAW264.7 macrophages, curcumin, CUR-SD, and F7 showed comparable and potent anti-inflammatory activity (IC₅₀ = 4.12–4.84 µg/mL), outperforming indomethacin. In 3T3-L1 adipocytes, F7 significantly reduced lipid accumulation (~47%) in a concentration-dependent manner. These findings demonstrate that this transformable chewable in situ gelling platform is a promising gastroretentive strategy for improving the oral therapeutic efficacy of poorly soluble bioactive compounds for anti-obesity applications. Full article

Carrageenan (CGN) is widely used in processed foods and is typically supplied as a commercial preparation blended with other hydrocolloids to improve gelling properties, rather than as a single purified polymer. However, safety evaluations and mechanistic studies have largely focused on CGN in isolation; as a result, the biological effects of commercial CGN preparations (CGNPs) under realistic exposure conditions are still insufficiently characterized. In this study, the structural characteristics of three commercial food-grade CGNPs intended for meat products, soft sweets, and jelly were investigated. Furthermore, their effects on colitis were assessed, along with their impacts on the gut microbiota and related metabolites. The results indicated that all three CGNPs were κ-type, but differed in monosaccharide composition and molecular weight, which may contribute to their biological differences. In vivo, the CGNP intended for soft sweets significantly reduced the disease activity index (n = 6/group, p < 0.05) and helped maintain colon length (n = 6/group, p < 0.05). This CGNP also markedly reduced the abundance of Escherichia-Shigella and Helicobacter, while increasing propionate levels (n = 6/group, p < 0.05). In contrast, CGNPs intended for meat products and jelly tended to exacerbate colitis and increased the abundance of Enterococcus, a genus associated with colitis. These findings reveal the application-specific biological effects of commercial food-grade CGNPs and provide a basis for optimizing the application of these preparations in the food industry. Full article

This study investigated the properties of red algae (RA) biocomposite films reinforced with natural sisal fibers and plasticized with glycerol. The polymer was extracted from locally sourced red seaweed and combined sisal fibers at varying fiber loadings (0–45 wt%) using the doctor blading technique. Composite films were analyzed using a variety of methods to evaluate the chemical composition, thermal behavior and mechanical performance. Infrared spectroscopy confirmed the presence of kappa-carrageenan as the dominant polysaccharide in the RA matrix, whereas elemental analysis verified the dilution of sulfur content and enrichment of carbon with increasing fiber incorporation. Thermal stability increased with fiber loading, peaking at 30 wt% sisal fiber before decreasing slightly at 45 wt% due to poor fiber dispersion. Mechanical testing demonstrated an optimal balance between strength and flexibility at 30 wt% sisal fiber, with a 37% increase in strength compared to the pure RA film. Overall, the findings demonstrate that sisal fiber reinforcement enhances the structural integrity and stability of RA-based films, supporting their potential as biodegradable alternatives to petroleum-based plastics. Full article

Due to the allergenicity of soy protein, this study aimed to develop a hypoallergenic, dysphagia-friendly matrix using pea protein isolate. We investigated the effects of three hydrocolloid thickeners—xanthan gum (XG), guar gum (G), and carrageenan (C)—at various concentrations on the matrices’ rheological properties, textural characteristics, and dysphagia diet classification. The unthickened pea protein base was unstable, exhibiting rapid phase separation and low viscosity, unsuitable for dysphagia diets. The addition of XG (0.4–0.6 g), G (0.5–1.0 g), and C (0.8–1.2 g) successfully produced food matrices meeting the slightly, mildly, and moderately thick levels of the Japanese Society of Dysphagia Rehabilitation (JSDR) framework. However, discrepancies were noted between instrumental viscosity and syringe flow test classifications. Rheological analysis revealed that XG samples were in elastic (G′ > G″) domain in the linear viscoelastic region (LVR) and exhibited shear-thinning behavior. In contrast, G and C samples were in viscous (G″ > G′) domain. Frequency sweeps characterize XG samples as weak gels, G samples as dilute polymer solutions, and C samples as gel-like structures. Texture profile analysis further showed that xanthan gum imparted the highest firmness and thickness, whereas guar gum provided the best flowability. Full article

Hybrid polysaccharide-based aerogels offer significant potential as advanced drug delivery platforms due to their tunable structure, high porosity, and biocompatibility. In this study, aerogel microparticles were synthesized using alginate, pectin, carrageenan, and their hybrid formulations via an emulsion–gelation technique followed by supercritical fluid CO₂ extraction. The resulting aerogels exhibit mesoporous structures with specific surface areas ranging from 324 to 521 m²/g and pore volumes between 1.99 and 3.75 cm³/g. Comprehensive characterization (SEM, gas sorption, XRD, TGA, DSC, and FTIR) confirmed that hybridization improved morphological uniformity and thermal stability compared to single polymer aerogels. Ibuprofen was used as a model drug to evaluate loading efficiency and release kinetics. Among all formulations, the alginate/carrageenan (2:1) hybrid showed the highest drug loading efficiency (93.5%) and a rapid release profile (>90% within 15 min), closely matching the performance of commercial ibuprofen tablets. Drug release followed Fickian diffusion, as confirmed by the Korsmeyer–Peppas model (R² > 0.99). These results highlight the potential of hybrid polysaccharide aerogels as vehicles for drug delivery and other fast-acting therapeutic applications. Full article

In FRET-based sensing, the interaction between the analytes and metal nanoparticles is significantly regulated by the physicochemical characteristics of the nanoparticles, such as their shape, size, zeta potential, surface-linked ligands, doping, pH of the medium, particle surface roughness, and lattice structure (atomic arrangements). During the synthesis process, to avert the aggregation of gold nanoparticles (AuNPs), synthetic polymers (including polyethylene glycol, polyethyleneimine, and poly-N-vinylpyrrolidone) and natural polymers (such as chitosan, starch, gellan, welan, and κ-carrageenan) are frequently employed for stabilization. This stabilization is accomplished through mechanisms such as steric repulsion and electrostatic stabilization, which form a protective layer around AuNPs. These stabilizing polymers act as molecular spacers in nanoparticle-based FRET sensing, enabling the precise regulation of the molecular distance between the acceptor and donor fluorophore molecules. This regulation enhances the efficiency and sensitivity of FRET assays. By modifying the length and flexibility of the spacer polymer, researchers can adjust the spacing between fluorophores, ensuring effective energy transfer and the accurate detection of target molecules. However, there is a limited understanding of the role and broad application of these molecular spacers in nanoparticle-mediated FRET-based sensing of various analytes. Consequently, this review explores different fundamental aspects of FRET, polymeric stabilization of gold nanoparticles, and various polymeric spacers in FRET-based sensing, along with the recent advancements and challenges associated with this approach. Full article

In the field of advanced electrical energy conversion and storage, remarkable attention has been given to the development of new, more sustainable electrolytes. In this regard, the combination of redox shuttles with aqueous bio-polymer gels seems to be a valid alternative via which to overcome the typical drawbacks of common liquid electrolytes such as corrosion, volatility or leakage. Despite the promising results obtained so far, redox-active species such as bis(6,6′-dimethyl-2,2′-bipyridine)copper(I) trifluoromethanesulfonylimide, ([Cu(I)(dmby)₂]TFSI), still present inherent challenges associated with their poor water solubility and oxidative lability, which prevents their employment in cheap and sustainable aqueous electrolytes. The present study investigates the stabilization of the Cu(I) complex ([Cu(I)(dmby)₂]TFSI) within two natural hydrogels based on the biopolymers κ-carrageenan and galactomannan, using ZnO nanoparticles as gelling agents. These eco-friendly and biocompatible systems are proposed as potential matrices for quasi-solid electrolytes (QSEs), offering a promising platform for advanced electrolyte design in electrochemical applications. Both hydrogels effectively stabilized and retained the redox species within their networks. In order to shed light on distinct stabilization mechanisms, complementary FTIR and SEM analyses were relevant to reveal the structural rearrangements, specific to each matrix, upon complex incorporation. Furthermore, thermogravimetric analysis confirmed notable thermal resilience in both systems, with the galactomannan-based gel demonstrating enhanced performance. Altogether, this work introduces a novel strategy for embedding copper-based redox couples into gelled electrolytes, paving the way toward their integration in real electrochemical devices, where long-term stability, redox retention, and energy conversion efficiency are critical evaluation criteria. Full article

A metal-ion-free method was developed to prepare κ-carrageenan/cellulose hydrogel beads for efficient cationic dye removal. The beads were fabricated using a mixture of 1-ethyl-3-methylimidazolium acetate and N,N-dimethylformamide as the solvent system, followed by aqueous ethanol-induced phase separation. This process eliminated the need for metal-ion crosslinkers, which typically neutralize anionic sulfate groups in κ-carrageenan, thereby preserving a high density of accessible binding sites. The resulting beads formed robust interpenetrating polymer networks. The initial swelling ratio reached up to 28.3 g/g, and even after drying, the adsorption capacity remained over 50% of the original. The maximum adsorption capacity for crystal violet was 241 mg/g, increasing proportionally with κ-carrageenan content due to the higher surface concentration of anionic sulfate groups. Kinetic and isotherm analyses revealed pseudo-second-order and Langmuir-type monolayer adsorption, respectively, while thermodynamic parameters indicated that the process was spontaneous and exothermic. The beads retained structural integrity and adsorption performance across pH 3–9 and maintained over 90% of their capacity after five reuse cycles. These findings demonstrate that κ-carrageenan/cellulose hydrogel beads prepared via a metal-ion-free strategy offer a sustainable and effective platform for cationic dye removal from wastewater, with potential for heavy metal ion adsorption. Full article

Natural polymers, polysaccharides, demonstrate piezoelectric behavior suitable for force sensor manufacturing. Carrageenan hydrogel film with α-iron oxide particles can act as a piezoelectric polysaccharide-based force sensor. The mechanical impact on the hydrogel caused by a falling ball shows the impact response time, which is measured in milliseconds. Repeating several experiments in a row shows the dynamics of fatigue, which does not reduce the speed of response to impact. Through the practical experiments, we sought to demonstrate how theoretical knowledge describes the hydrogel we elaborated, which works as a piezoelectric material. In addition to the theoretical basis, which includes the operation of the metal and metal oxide contact junction, the interaction between the metal oxide and the hydrogel surfaces, the paper presents the practical application of this knowledge to the complex hydrogel film. The simple calculations presented in this paper are intended to predict the hydrogel film’s characteristics and explain the results obtained during practical experiments. Carrageenan, as a low-cost and already widely used polysaccharide in various industries, is suitable for the production of low-cost force sensors in combination with iron oxide. Full article

Industrial textile wastewater containing both heavy metals and dyes has been massively produced. In this study, semi-interpenetrating polymer network structures of sodium alginate (SA)/polyvinyl alcohol (PVA)/κ-carrageenan (CG) aerogel beads were synthesized for their simultaneous reduction. The SA/PVA/CG aerogel beads were synthesized through a cost-effective and environmentally friendly method using naturally abundant biopolymers without toxic cross-linkers. The SA/PVA/CG aerogel beads were spheres with a size of 3.8 $\pm$ 0.1 mm, exhibiting total pore areas of 15.2 m²/g and porous structures (pore size distribution: 0.04–242.7 μm; porosity: 93.97%) with abundant hydrogen bonding, high water absorption capacity, and chemical resistance. The adsorption capacity and mechanisms of the SA/PVA/CG aerogel beads were investigated through kinetic and isotherm experiments for heavy metals (Cu(II), Pb(II)), cationic dye (methylene blue, MB), and anionic dye (acid blue 25, AB)) in both single and binary systems. The maximum adsorption capacities of the SA/PVA/CG aerogel beads based on the Langmuir model of Cu(II), Pb(II), and MB were 85.17, 265.98, and 1324.30 mg/g, respectively. Pb(II) showed higher adsorption affinity than Cu(II) based on ionic properties, such as electronegativity and hydration radius. The adsorption of Cu(II), Pb(II), and MB on the SA/PVA/CG aerogel beads was spontaneous, with heavy metals and MB exhibiting endothermic and exothermic natures, respectively. Full article

The amorphization and crystallization of citric acid in the presence of a variety of polymers were investigated. Polymers were chosen for their different physicochemical features, including hygroscopicity, glass transition temperature (T_g), and functional groups capable of forming intermolecular non-covalent interactions with citric acid. Citric acid solutions with varying amounts of pectin (PEC), guar gum (GG), κ-carrageenan (KG), gelatin (GEL), (hydroxypropyl)methylcellulose (HPMC), and carboxymethylcellulose sodium (CMC-Na) were lyophilized. Dispersions were stored for up to 6 months in controlled temperature and relative humidity environments and periodically monitored using powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Moisture sorption isotherms and moisture contents were determined. Amorphous solid dispersions of citric acid were successfully formed in the presence of ≥20% w/w CMC-Na and PEC or ≥30% w/w of the other polymers except KG which required a minimum of 40% polymer. All samples remained amorphous even in their rubbery state at 0% RH (25 °C and 40 °C), but increasing the RH to 32% RH resulted in citric acid crystallization in the KG dispersions, and further increasing to 54% RH resulted in crystallization in all samples. Polymer effectiveness for inhibiting citric acid crystallization was CMC-Na > PEC ≥ GEL > HPMC > GG > KG. To create and maintain amorphous citric acid, polymer traits in order of effectiveness were as follows: greater propensity for intermolecular non-covalent interactions (both ionic and hydrogen bonding) with the citric acid, carbonyl groups, higher T_g, and then lower hygroscopicity. Full article