Search Results (206)

Hydrogel films receive significant attention among researchers because they combine increased stimuli responsiveness and faster responses to the already excellent properties of their component materials. However, their preparation is complex and requires that many difficulties are overcome. The present work presents a new study regarding the preparation of pure and nanoparticle-loaded alginate-based films by spin-coating. Two-microliter solutions of sodium alginate and calcium chloride with different concentrations were deposited on a glass substrate and subjected to rapid rotations of between 100 and 1000 RPM. Film formation can be achieved by optimizing the ratio between the viscosity of the solutions, depending on their concentrations and the rotation speed. When these conditions are in the right range, a homogeneous film is obtained, showing good adherence to the substrate and uniform thickness. Films containing silver nanoparticles were prepared, exploiting the reaction between sodium borohydride and silver nitrate. The two reagents were added to the sodium alginate and calcium nitrate solution, respectively. Their concentration is the driving force for the formation of a uniform film: particles of about 50 nm that are well-dispersed throughout the film are obtained using AgNO₃ at 4 mM and NaBH₄ at 2 or 0.2 mM; meanwhile, at higher concentrations, one can also obtain the precipitation of inorganic crystals. Full article

The increasing prevalence of antibiotic-resistant bacteria has stimulated the search for alternative antimicrobial agents with greater efficacy, low toxicity, and minimal resistance potential. Natural products, such as honey, propolis, and royal jelly, have shown promise due to their biological properties. The integration of natural products like honey and propolis in biomaterials represents a synergistic approach to combat the growing threat of resistant bacterial infections while improving wound care and soft tissue engineering applications. In the present work, we obtained sodium alginate films based on honey, propolis, royal jelly, and their mixture coated with chitosan for soft tissue regeneration. SEM showed that adding bee products altered surface morphology, affecting roughness, porosity, and microstructure. Spectral analysis confirmed specific chemical bonds, while thermal studies indicated a good stability up to 115 °C. The antimicrobial activity was evaluated against Gram-positive (Enterococcus faecalis, Staphylococcus aureus), Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and yeast strains (Candida albicans), with growth inhibition zone diameters up to 12 mm. In vitro cytotoxicity studies, made on human gingival fibroblasts, suggested good biocompatibility. Antimicrobial assays showed that films containing propolis tincture, alone or as a mixture, were most effective against pathogens. Future research will focus on formulation optimization for biomedical use. Full article

This study develops a sustainable biopolymer film derived from potato peel waste (PW), enhanced with low- and high-viscosity sodium alginate (SA) through a solution casting method. The effect of calcium chloride crosslinking on the PW/SA composites was also evaluated. Scanning electron microscopy (SEM) analysis revealed that SA incorporation improved the film’s cohesion and uniformity, with both low- and high-viscosity SA showing nearly similar effects. Both the addition of SA and crosslinking led to enhanced tensile strength, as well as improved moisture barrier properties, by lowering the water vapor permeability (WVP) factor. The inclusion of high-viscosity SA (hvSA) resulted in superior mechanical and moisture barrier properties compared to the low-viscosity SA (lvSA), achieving a tensile strength of 5.34 MPa, with a 68% improvement compared to the pure PW film. The WVP analysis showed that hvSA had a superior impact, leading to a 32% reduction in WVP compared to the pure film. Crosslinking further boosted the tensile strength and moisture barrier properties. The crosslinked hvSA/PW composite shows the highest tensile strength among all samples, measuring 6.47 MPa, which accounts for a 104% enhancement compared to the pure film. It also led to a 34% reduction in WVP, reaching a value of 1.58 × 10⁻¹² g/(Pa·cm·s). The findings demonstrate that PW/SA composites, especially the crosslinked hvSA/PW, offer the highest mechanical and barrier properties, making them suitable for biodegradable packaging and biomedical applications. Full article

Biodegradable mulch films were developed over the last decades to replace polyethylene, but their short durability and higher costs still limit their diffusion. This work aimed to test an innovative composite mulching film constituted by a mixture of carboxylmethyl cellulose, chitosan and sodium alginate, enriched or not with an inorganic N- and P-source to help the microbial breakdown in soil. The trial was carried out using outdoor mesocosms cultivated with lettuce plants with high-density planting. Commercial Mater-Bi^® and a polyethylene film were taken as control treatments. Air temperature and humidity monitored daily during the 51 d cropping cycle remained within the ideal range for lettuce growth with no mildew or fungi infection. Visible mechanical degradation of the experimental biopolymers occurred after 3 weeks; however, Mater-Bi^® and polyethylene remained unaltered until harvest. Chemical soil variables (TOC, TN, CEC, EC) remained unchanged in all theses, whereas the pH varied. The yield, pigments, total phenols, flavonoids and ROS scavenging activity of lettuce were similar among treatments. Despite their shorter life service (~3 weeks), polysaccharide-based mulching films showed their potential to protect lettuce plants at an early stage and provide yield and nutraceutical values similar to conventionally mulched plants, while allowing a reduced environmental impact and disposal operations. Full article

Fruits are a significant source of natural nutrition for human health. However, the perishable nature and short shelf life of fruits lead to spoilage, nutrition safety challenges, and other substantial postharvest losses. Edible coatings have emerged as a novel approach in order to enhance the shelf life of perishable fruits by forming a protective barrier against adverse environmental conditions and microbial infections. Sodium alginate is recognized as an excellent polysaccharide (derived from algae, seaweed, etc.) in the food industry for edible fruit coatings because of its non-allergic, biodegradable, non-toxic (safe for human health), inexpensive, and efficient gel/film-forming properties. However, the hydrophilicity of the polysaccharides is a significant concern to prevent the growth of mold and yeast. In recent years, various plant extracts (containing multiple bioactive compounds, including polyphenolic acids) and nanoparticles have been applied in sodium alginate-based edible films and fruit coatings to enhance antimicrobial activity. This review study summarized recent advancements in fabricating plant extracts incorporating sodium alginate-based films and coatings to enhance fruit shelf life. In addition, approaches to preparing edible films and the basic mechanism behind the role of coating materials in enhancing fruit shelf life are discussed. Moreover, the limitations associated with sodium alginate-based fruit coatings and films have been highlighted. Full article

The objective of this research was to prepare robust edible films possessing antioxidant properties by utilizing konjac glucomannan (KGM), sodium alginate (SA), and epigallocatechin gallate (EGCG). This research also involved structural characterization and the assessment of functional attributes of the composite films with varying EGCG concentrations. It was found that the inclusion of EGCG reduced the viscosity of the edible film solutions while enhancing their mechanical strength. Fourier transform infrared spectroscopy demonstrated adequate compatibility among the film-forming materials, with EGCG forming hydrogen bond interactions with KGM and SA. SEM analysis revealed that increasing EGCG concentration led to the formation of discontinuous blocks and rough surfaces, with smooth and fine-grained particles observed at 0.2% (w/v) EGCG concentration. Furthermore, results from the application of the KGM-SA-based films in chilled mandarin fish showed that they could exert antioxidant function when incorporated with EGCG. The values of TVB-N and TBARS of fish pieces were obviously decreased in the 12-day storage period, indicating their potential to increase the shelf life of freshwater fish food. Full article

Polysaccharides and proteins are the primary components of edible films used for food packaging. Adding plasticizers such as glycerol or sorbitol during manufacturing can help enhance the properties of films derived from biopolymer combinations. In this study, we aimed to produce sodium alginate/gum arabic/gluten edible films and evaluate the effects of various concentrations of glycerol and sorbitol used as plasticizers on the films’ physical, mechanical, barrier, and optical properties. Using solvent casting, an edible film based on sodium alginate/gum arabic/gluten was plasticized with either glycerol or sorbitol at concentrations of 2, 4, and 6% (w/v). The properties of the edible films were then characterized. Decreases in solubility, tensile strength, and water vapor transmission rate were observed when higher glycerol and sorbitol concentrations were added. The films plasticized with 6% glycerol and 6% sorbitol had the lowest solubility, tensile strength, and water vapor transmission rates. In addition, the films plasticized with glycerol, regardless of concentration, had lower transparency values than those plasticized with sorbitol. The addition of glycerol and sorbitol had insignificant effects on the thickness properties and L values of the films. The absorption peaks of the Fourier-transform infrared spectra patterns of the films plasticized with sorbitol and glycerol were similar, confirming there was an interaction between the plasticizers and polymers. Together, the results demonstrate that sorbitol and glycerol are compatible with sodium alginate/gum arabic/gluten film-forming solutions, indicating that the films obtained could be employed for food packaging. Full article

The development of sustainable biodegradable packaging materials is essential for enhancing food quality and shelf life while reducing plastic waste. This study explored polymer-based monolayer, composite, and bilayer films to produce water-soluble, oil-proof pouches. Single-serving seasoning oil pouches were prepared from bilayer films with polyvinyl alcohol (PVA) as the inner and sodium alginate (SA) as the outer layer. The PVA/SA films exhibited excellent UV protection, low oil permeability (0.18 × 10⁻⁶ g·mm/mm²·day), hydrophilic surface (water contact angle < 90°), and rapid solubility in hot water (87 ± 2 °C). Incorporating curcumin, a natural antioxidant, into PVA/SA films (Cur-PVA/SA) improved thermal stability, reduced light transmittance, and decreased water vapor permeability (0.28 × 10⁻¹⁰ g/m·Pa·s). Curcumin release followed a biphasic diffusion model, with 94.8% released at 96 h (diffusion coefficient: 1.30 × 10⁻¹¹ m²/s), ensuring prolonged antioxidant activity. The Cur-PVA/SA pouches delayed lipid oxidation more effectively, with peroxide values of 6.48 and 10.35 meq/kg after 45 days at 35 °C, respectively. The Q₁₀ model, which is commonly used to predict the shelf life of oils based on temperature-dependent oxidation rates, estimated that the oil packaged in Cur-PVA/SA pouches would remain stable for 12 months at 23 °C. This represents a 37% longer shelf life compared to oil packaged in PVA/SA pouches without curcumin. Cur-PVA/SA pouches also reduced noodle moisture migration, limiting weight loss to 2.73% over 14 days compared to 5.80% in controls. These findings highlight their potential as eco-friendly active packaging solutions. Full article

The impact of a glycerol–silicate (GS) plasticizer on the mechanical, thermal and hydrophobic properties pertaining to sodium alginate (NaAlg) and calcium alginate (CaAlg) films were investigated. Spectroscopic and physio-chemical analysis were conducted to evaluate the effects of the GS incorporation. The results determine that both NaAlg and CaAlg films exhibited poor mechanical properties which only improved by increasing the GS loading (up to 25 wt%), after which it declined. CaAlg exhibited the highest tensile strength after 25 wt% GS loading was incorporated. The elongation at break varied, with NaAlg films showing a ~10-fold increase, while the CaAlg films remained relatively unchanged. Thermal gravimetric analysis (TGA) revealed that GS reduced the onset decomposition temperature of NaAlg films, whereas CaAlg films maintained a greater onset decomposition temperature. The advancing contact angle measurements indicated a nearly linear decrease (from 54° to 39°) in hydrophobicity for the NaAlg films while the hydrophobicity for CaAlg films initially increased from 65° to 74°, and then became more hydrophilic with greater GS loading. These findings highlight the potential of GS plasticization to enhance and tailor alginate film properties, providing insights into the development of sustainable bioplastics with improved mechanical properties. Full article

Owing to its natural degradability and excellent film-forming characteristics, sodium alginate (SA) is gaining growing popularity in the field of food packaging. However, the insufficient antioxidant and antibacterial properties hinder its application. In the current research, protocatechuic acid (PCA) and Fe³⁺ were utilized to fabricate a metal polyphenol network structure. Subsequently, geranium essential oil emulsion (GEOE) was incorporated into the SA matrix, and SA-based films were prepared through the flat-sheet casting method. The impacts of PCA/Fe and various concentrations of GEOE on the physical, structural, as well as functional characteristics of SA-based films were comprehensively examined. The thickness of the prepared SA-based films was between 30 and 50 μm. The results showed that PCA/Fe, GEOE, and SA exhibited good biocompatibility, and the formed films were uniform. The incorporation of PCA/Fe and GEOE significantly improved the UV blocking ability, thermal stability, and antibacterial activity of SA-based films. In addition, PCA/Fe and GEOE enhanced the total antioxidant capacity of SA-based films from 3.5% to 88%. This research could provide some theoretical basis for the utilization of metal polyphenol networks and natural essential oils within the realm of food active packaging films. Full article

To address the increasingly diverse demands for biodegradable packaging materials, such as for their physical properties and antioxidant properties, this study incorporated tea polyphenols (TPs) into soybean oil body emulsions (SOBs) and added a certain proportion of sodium alginate (SA) and octenyl succinic starch sodium (SSOS) to prepare a biodegradable soybean oil body–tea polyphenol (ST) emulsion film. The study systematically evaluated the effects of different concentrations of TP (0–6 wt.%) on the structure, physicochemical properties, antioxidant activity, and antibacterial activity of ST films. The results showed that the physical properties, such as tensile strength and elongation at break, of the films increased significantly with the addition of TP, and the antioxidant and antibacterial activity also increased with the increase in TP concentration. When TP concentration was 2.5 wt.%, the barrier properties of the film (ST-2.5) significantly improved (p < 0.05), while water content and water solubility decreased. The Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis results showed that the structure of ST films became tighter at this point. The addition of TP also affected the sensory properties of ST films, such as with an increase in the opacity of the film. Compared with the control, the light transmittance of ST-6.0 decreased by 23.68% at a wavelength of 600 nm, indicating a significant reduction in film transparency. Moreover, the biodegradability test showed that ST films have good degradability. Therefore, the ST film, as a functional edible film, has broad application prospects in the food packaging industry. Full article

Background/Objectives: Interest in 3D printing oral thin films (OTFs) has increased substantially. The challenge of 3D printing is film printability, which is strongly affected by the rheological properties of the ink and having suitable mechanical properties. This research assesses the suitability of sodium starch glycolate (SSG), a swellable cross-linked biopolymer, on ink rheology and the film’s mechanical properties. Methods: A water-based ink comprising sodium alginate (SA), the drug fenofibrate (FNB), SSG, glycerin, and polyvinylpyrrolidone (PVP) was formulated, and its rheology was assessed through flow, amplitude sweeps, and thixotropy tests. Films (10 mm × 15 mm × 0.35 mm) were 3D-printed using a 410 µm nozzle, 50% infill density, 60 kPa pressure, and 10 mm/s speed, with mechanical properties (Young’s modulus, tensile strength, and elongation at break) analyzed using a TA-XT Plus C texture analyzer. Results: The rheology showed SSG-based ink has suitable properties (shear-thinning behavior, high viscosity, higher modulus, and quick recovery) for 3D printing. SSG enhanced the rheology (viscosity and modulus) of ink but not the mechanical properties of film. XRD and DSC confirmed preserved FNB crystallinity without polymorphic changes. SEM images showed surface morphology and particle distribution across the film. The film demonstrated a drug loading of 44.28% (RSD 5.62%) and a dissolution rate of ~77% within 30 min. Conclusions: SSG improves ink rheology, makes it compatible with 3D printing, and enhances drug dissolution (formulation F-5). Plasticizer glycerin is essential with SSG to achieve the film’s required mechanical properties. The study confirms SSG’s suitability for 3D printing of OTFs. Full article

Three-dimensional printing is promising in the pharmaceutical industry for personalized medicine, on-demand production, tailored drug loading, etc. Pressure-assisted microsyringe (PAM) printing is popular due to its low cost, simple operation, and compatibility with heat-sensitive drugs but is limited by ink formulations lacking the essential characteristics, impacting their performance. This study evaluates inks based on sodium alginate (SA), hydroxypropyl cellulose (HPC H), and hydroxypropyl methylcellulose (HPMC K100 and K4) for PAM 3D printing by analyzing their rheology. The formulations included the model drug Fenofibrate, functional excipients (e.g., mannitol, polyethylene glycol, etc.), and water or water–ethanol mixtures. Pills and thin films as an oral dosage were printed using a 410 μm nozzle, a 10 mm/s speed, a 50% infill density, and a 60 kPa pressure. Among the various formulated inks, only the ink containing 0.8% SA achieved successful prints with the desired shape fidelity, linked to its rheological properties, which were assessed using flow, amplitude sweep, and thixotropy tests. This study concludes that (i) an ink’s rheological properties—viscosity, shear thinning, viscoelasticity, modulus, flow point, recovery, etc.—have to be considered to determine whether it will print well; (ii) printability is independent of the dosage form; and (iii) the optimal inks are viscoelastic solids with specific rheological traits. This research provides insights for developing polymer-based inks for effective PAM 3D printing in pharmaceuticals. Full article

In this study, biodegradable and active films based on sodium alginate incorporated with different concentrations of oils (25% and 50%) from fruit seeds were developed for potential applications in food packaging. The ultraviolet and visible (UV-VIS) spectra of raspberry seed oil (RSO) and black currant seed oil (BCSO) indicated differences in bioactive compounds, such as tocopherols, phenolic compounds, carotenoids, chlorophyll, and oxidative status (amounts of dienes, trienes, and tetraenes) of active components added to alginate films. The study encompassed the color, structure, and thermal stability analysis of sodium alginate films incorporated with RSO and BCSO and their mixtures. The color of alginate films before and after the addition of oils from both fruit seeds was evaluated by measuring color coordinates in the CIELab color space: L* (lightness), a* (red-green), and b* (yellow-blue). The lightness values ranged between 94.21 and 95.08, and the redness values varied from −2.20 to −2.65, slightly decreasing for the films enriched with oils. In contrast, yellowness values ranged between 2.93 and 5.80 for the obtained active materials, significantly increasing compared to the control alginate film (L* = 95.48, a* = −1.92, and b* = −0.14). Changes in the structure and morphology of the alginate films after incorporating bioactive-rich oils were observed using scanning electron microscopy (SEM). Films with RSO and oil mixtures had more developed surfaces than films with BCSO. Moreover, the cross-sections of the films with RSO showed holes evenly distributed inside the films, indicating traces of volatile compounds. Thermal decomposition of the alginate films loaded with oils showed five separate stages (to 125 °C, 125–300 °C, 310–410 °C, 410–510 °C, and 750–1000 °C, respectively) related to the oil and surfactant decomposition. The shape of the thermogravimetric curves did not depend on the oil type. The added oils reduced the efficiency of alginate decomposition in the first stage. The obtained results showed that new functional and thermally stable food packaging films based on sodium alginate with a visual appearance acceptable to consumers could be produced by utilizing oils from fruit seed residues. Full article

Freshness indicator labels are crucial for food quality monitoring. However, existing labels often lack stability and sensitivity. This study aims to develop a safe freshness indicator label with high stability and sensitivity. By evaluating the pH response characteristics and stability of four natural pigments, purple potato anthocyanin (PA) was identified as having the best color properties. Mixing the more stable alizarin (AL) with PA improved the stability of the pigment solution without reducing sensitivity. These film labels are prepared with three natural biomolecules and polymers that are a two-by-two composite of them: soybean isolate protein, acacia bean gum, and sodium alginate. Through comparisons of ammonia response, color stability, water solubility, and mechanical properties, the soy protein isolate and locust bean gum composite were determined to be the optimal substrate system. The label of soybean protein isolate and locust bean gum was initially applied to the freshness identification of shrimp and chicken. The results show that the label can effectively respond to the spoilage of aquatic products and meat products and has great application potential in the field of food packaging. Full article