Journal of Polymers and the Environment最新文献

In situ forming hydrogel scaffolds are essential in bone tissue engineering due to their ability to influence the behavior of seeded cells through their composition and physicochemical properties. However, many existing in situ forming hydrogels that rely solely on physical cross-linkers suffer from poor mechanical strength and inadequate gelation times. In this study, an interpenetrating network (IPN) hydrogel composed of silk fibroin (FIB), sodium alginate (ALG), and sodium alendronate (ALN) was developed, using Ca²⁺ ions as the physical cross-linking agent. ALN was incorporated into the FIB/ALG hydrogel matrix to enhance mechanical performance and regulate gelation kinetics. Increasing ALN content significantly improved the compressive modulus of the hydrogels from 28 kPa to 67 kPa. Additionally, the FIB/ALG/ALN hydrogels exhibited prolonged gelation times (25–72 s), in contrast to the nearly instantaneous gelation observed in FIB/ALG hydrogels. In vitro release studies revealed a sustained release of ALN over 20 days, attributed to ionic interactions between the phosphate groups of ALN and the hydrogel network. Cell viability assays demonstrated excellent biocompatibility and confirmed the hydrogel’s ability to support stem cell adhesion, growth, and proliferation. These findings highlight the potential of FIB/ALG/ALN hydrogels as promising in situ forming scaffolds for bone tissue regeneration.

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This study prepared wholly deacetylated, low-molecular-weight chitooligosaccharides (COS) through cellulase disintegration of chitosan sourced from shrimp and crab to produce (SCO) and CCO, respectively. FTIR analysis showed that the employed conditions (55 °C, pH 5.2 in 24 h) enabled nearly complete deacetylation, 98.8% and 100%, with average molecular weights of 1.288 and 0.467 kDa, respectively. The ESI/MS findings revealed that the resulting COS consisted of monomers and polymers of D-glucosamine (1–6 units). The COS demonstrated a progressive increase in water solubility, culminating at 88% and displayed exceptional bioactivities, particularly in their scavenging activity against DPPH at concentrations of 1–6 mg/mL. SCO produced scavenging rates equivalent to 54.72 ± 2%-60.18 ± 1%, against 59.11 ± 1%- 65.29 ± 1% in the case of CCO. The antibacterial efficacy COS (1200 µg/mL) revealed maximum inhibition zones of 26 ± 1 and 22 ± 1 mm against Bacillus cereus and Escherichia coli. The inclusion of COS in yogurt and orange juice reduced the total aerobic count by about 0.7 ± 0.1 log CFU/mL and garnered excellent sensorial acceptability ratings, exceeding 4 ± 0.0. This study is innovatively using cellulase, a cost-effective, widely available enzyme, to produce fully deacetylated, low-molecular-weight COS from marine shell waste. These ameliorated COSs offer a sustainable alternative to synthetic preservatives, particularly in yogurt and orange juice. They present a potential in green food preservation and an eco-friendly approach to transforming seafood waste into high-value bioactive compounds.

Ammonium ((:{text{N}text{H}}_{4}^{+})) is a widely used fertilizer; however, its presence in water sources poses significant risks to both human health and the environment. To address this issue, it is necessary to implement cost-effective strategies that control fertilizer release, mitigate environmental impact, and remove (:{text{N}text{H}}_{4}^{+}) from water sources for reducing negative processes such as eutrophication. In this study, oxidized cassava starch was synthesized using sodium hypochlorite (NaClO) as an oxidizing agent to introduce carboxylic groups, which can interact favorably with (:{text{N}text{H}}_{4}^{+}) ions. The oxidation of starch was evaluated at different NaClO concentrations and pH values, and the resulting materials were characterized by ATR-FTIR, TGA, SEM, carboxyl content determination, and swelling assays. Oxidation was confirmed by ATR-FTIR and TGA results. The optimal conditions were determined to be pH 7 and 2% NaClO, which produced the highest carboxyl content (0.19 ± 0.017) and a high gel fraction (82.6 ± 1.8%). Additionally, the materials exhibited a porous surface and high-water retention capacity, indicating hydrogel formation resulting from hydrogen bonding between starch polymer chains. The adsorption potential of the material for (:{text{N}text{H}}_{4}^{+}) was evaluated, achieving a high retention capacity of 2790.3 ± 37.8 mg/g. This suggests a possible precipitation of the ion on the hydrogel surface; however, this was not observed experimentally. The adsorption process followed a Freundlich isotherm and a pseudo-second-order kinetic model, indicating that adsorption occurs primarily through electrostatic interactions and in multilayers, likely involving the precipitation of (:{text{N}text{H}}_{4}^{+}) on the material’s surface. In addition, the material exhibited a slow-release behavior, with less than 20% of (::{text{N}text{H}}_{4}^{+}:)released over 26 days. These results demonstrate that the material possesses a high potential for (:{text{N}text{H}}_{4}^{+}:)adsorption and controlled release, making it suitable for applications in both controlled nutrient delivery and the removal of cationic pollutants from contaminated water sources.

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This study introduces a novel nanocomposite coating of tri-calcium phosphate (TCP), Acacia arabica extract (AA), polyvinyl alcohol (PVA), and silver nanoparticles (Ag-NPs) for titanium implants. Titanium’s use in biomedical applications is limited by its susceptibility to chloride-induced corrosion in simulated body fluid (SBF), which reduces bioactivity, may trigger inflammation, and offers inadequate antibacterial protection, potentially leading to implant failure. To address these challenges, the nanocomposite was synthesized via a green method and deposited on titanium using electrophoretic deposition (EPD). Electrochemical evaluations, including open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS), demonstrated marked corrosion protection, with inhibition efficiencies of 83.00% (PDP) and 95.18% (EIS). Surface characterization by UV-Vis, X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) confirmed successful, uniform coating deposition. Water contact angle measurements revealed enhanced hydrophilicity (54.2°) compared to uncoated Ti (67.5°), and adhesion testing indicated strong bonding with a pull-off strength of 5.1 MPa. Biological assessments confirmed potent antibacterial activity and reduced cytotoxicity, demonstrating the coating’s potential to improve implant performance. This work highlights TCP/AA/PVA/Ag-NPs as a promising multifunctional coating strategy to enhance titanium’s corrosion resistance, antibacterial efficacy, and biocompatibility for biomedical applications.

Injectable nanocomposite hydrogels composed of biodegradable biopolymers and conductive nanofillers were engineered to restore left-ventricular (LV) function after myocardial infarction (MI). Poly(vinyl alcohol) (PVA) served as the base matrix and was combined—in different formulations—with graphene oxide (GO), chitosan (Cs), boron (B), nanocellulose (Cell), gelatin (Gel), and gold nanoparticles (Au). The hydrogels were fabricated via freeze–thaw and chemical crosslinking, characterized for injectability and viscoelasticity, and evaluated in a rat MI model by intramyocardial injection followed by ECG, echocardiography, and histology at 14 days. Across groups, echocardiography showed significant between-group differences in ejection fraction (EF), stroke volume (SV), and cardiac output (CO). The full composite (PVA + Gel + GO + Cs + B + Cell + Au) yielded the highest EF (62.97 ± 10.32%) versus control (57.10 ± 5.96%; P = 0.015). A simplified conductive/adhesive formulation (PVA + GO + Cs + B) maximized SV (169.84 ± 67.62 µl vs. 62.54 ± 23.63 µl in control; P = 0.004) and CO (44.27 ± 31.01 ml/min vs. 18.72 ± 5.22 ml/min in control; P = 0.004). ECG parameters were largely comparable between groups, with no adverse conduction abnormalities. Histology (Masson’s trichrome/HE) corroborated reduced collagen deposition and improved tissue architecture in hydrogel-treated hearts. Overall, the optimized PVA-based nanocomposites improved LV function after MI—most notably EF with the full composite and SV/CO with PVA + GO + Cs + B—highlighting a tunable platform for post-infarction cardiac repair. Unlike prior cardiac hydrogels that compare unrelated formulations, we held the total nanoparticle load constant and altered only the composition (GO, Cs, B, nanocellulose, Au) to isolate composition-dependent effects on injectability and repair, then validated the clinically intended ‘all-components’ formulation in vitro/in vivo. More investigate on specific mechanisms or systems such as extracellular vesicles on the proliferation-endorsing effect could cover the way for the development of a targeted biological therapeutic combination.

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The development of nanocomposites made of polylactic acid (PLA) and cellulose nanofibrils by conventional melt mixing methods often requires strategies to incorporate the nanocellulose in a way that aggregation is minimized, and that the filler characteristics inherent to its nanoscale are preserved. In the current work, nanocomposite films of PLA and different contents of bacterial nanocellulose (BNC) were obtained by cast extrusion. Aiming to limit nanofibril aggregation, three strategies of filler incorporation into the extruder were assayed: (i) direct addition of dried and milled BNC, (ii) use of PLA/BNC masterbatches prepared by solvent casting, and (iii) use of masterbatches of PLA and surface-acetylated BNC (AcBNC) prepared in the same way. Composite films were characterized in terms of morphology, optical, thermal, tensile and barrier properties. Results showed that masterbatch preparation notably enhanced nanocellulose dispersion within the PLA matrix, improving the optical, thermal, and barrier properties of the composites, although no significant gains in mechanical performance were observed. Overall, the masterbatch approach effectively minimized nanocellulose aggregation, serving as an attractive strategy to enhance filler dispersion in PLA-based composites processed by conventional thermoplastic processing techniques.

Retrograded starch (type 3 resistant starch) has garnered significant research interest due to its laxative properties. Nevertheless, the inherently low levels of retrograded starch in aged starch paste restrict its practical applications. The higher the content of resistant retrograded starch in aged starch, the more pronounced its laxative effect, the lower the energy intake, and the greater its benefit for weight management. Monascus strains designated as M1, M2, M3, M4, and M5 were isolated from various types of red mold rice with a view to enhancing the content of retrograded maize amylopectin combined with gliadin at the expense of not-retrograded amylopectin in aged starch paste. The findings demonstrated that the maximum level of retrograded maize amylopectin was attained under the conditions involving a starch-to-coix-seed ratio of 1:1, fermentation using strain M2 for 15 days at 32 °C, and an escalation from 39.5% to 73.1%. The findings, derived from analysis of FT-IR, ¹³C solid-state NMR, XRD and DSC, indicated that the decomposition of maize amylopectin within the amorphous region of aged starch was initiated by Monascus. Retrograded maize amylopectin has been observed to typically exhibit reflections at 17°, 20°, and 22°, with the dominant reflection occurring at approximately 19–20° increasing after fermentation. This study proposes a novel method for enhancing the retrograded starch content in aged starch paste without causing environmental pollution, thereby broadening the application potential of gluten.

Recently, various studies have been conducted on eco-friendly nanofilms and packaging coatings. This study explores the innovation of nanocomposite based smart packaging by utilizing the molecular structure, thermal stability, barrier properties, pH sensitivity, and color responsiveness of nanoanthocyanin pigments extracted from papaver petals. Nanoanthocyanin was obtained via solvent-assisted ultrasonic extraction and incorporated into polylactic acid/carbopol matrices at concentrations of 0%, 0.5%, 1%, and 2% to fabricate biodegradable films. In this research, permeability parameters, molecular analysis, and colorimetric measurements across a pH range of 1 to 14 were conducted.The results showed that the highest oxygen permeability was observed in the control sample (T₀) (3.733 meq/KgO₂), while the lowest was found in the treatment (T₄) (1.567 meq/KgO₂), containing 2% nanoanthocyanin. In other words, increasing nanoanthocyanin concentration in biodegradable nanocomposite films reduced oxygen permeability compared to the control film. On the other hand, optimized levels of 2% nanoanthocyanin and 0.2% carbopol (T₄) improved thermal stability (149.80 J/g) and crystallinity (44.2%) within the film matrix. Furthermore, the results revealed that treatment T₃ exhibited strong sensitivity to pH changes, especially between pH 2 and 6, positioning it as an ideal candidate for intelligent packaging. These advancements demonstrate that the presence of nanocarbopol as a reinforcing agent enhanced the network structure, uniformity, and flexibility of the films. Moreover, the incorporation of nanoanthocyanins and the improvement of their stability at specific pH levels make this nanocomposite a promising candidate for real-time visual monitoring of product freshness in environmentally friendly and sustainable packaging systems.

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Rising variability in electricity supply and increasing power density in electronics created a need for thermal storage to protect devices and support grid flexibility. Biodegradable phase change materials provided latent heat storage but often exhibited low thermal conductivity and a risk of leakage. Previous studies rarely quantified durability, ageing and design optimization of biodegradable expanded-graphite composites. This work aims to develop and optimize biodegradable polymer/expanded graphite phase change composites that deliver high thermal conductivity, stable latent heat storage, and controlled ageing for smart-grid applications. Composite panels of PHB, PHBV, and PCL were impregnated into expanded graphite scaffolds, and their structures and thermal responses were examined using microstructural and thermal analysis techniques under both fresh and aged conditions. Molecular dynamics simulations and response surface methodology were used to characterise interfacial transport and optimise graphite loading and processing temperature. The composites achieve strong in-plane thermal transport while preserving latent-heat capacity, as increased graphite content within 9–17 wt% raised conductivity by 30% with modest reductions in melting enthalpy. Latent heat retention during 500 thermal cycles remains high, with PCL- and PHBV-based panels retaining 94–97% of their initial enthalpy, and ageing in air produced mainly surface-localized oxidation while the internal function remained intact. Response surface analysis identifies expanded-graphite loading as the dominant design variable, with conductivity sensitivity near 0.031 W·m⁻¹·K⁻¹ per wt%. These findings support the use of biodegradable fixed-form composites as durable thermal buffers for demand-side management, waste-heat utilization and thermal regulation of power electronics within smart grids. Future work targets life-cycle assessment and scale-up of the manufacturing route for industrial deployment.

This paper details the synthesis, characterization, and application of a green Y₂O₃@Chitosan (YCS) nanocomposite, fabricated using a simple technique, for the removal of Pb²⁺ ions from aqueous solutions. The synthesized YCS were analyzed employing several techniques to assess elemental composition, crystalline structure, surface properties, interlayer spacing, and functional groups. The substantial surface area of 67.4 m² g⁻¹ facilitated the efficient adsorption of Pb²⁺ ions at starting metal ion concentrations ranging from 5.0 to 200 mg. L^− 1. The study examined an adsorption contact duration of 1440 min, beginning solution pH levels of 1, 3 and 5 and an adsorbent dosage of 10 mg. Adsorption experiments indicated that optimal elimination of Pb²⁺ ions occurred within 63.5 min after achieving adsorption equilibrium, with a maximum adsorption capacity of 247.2 mg. g⁻¹ at pH 5.0, 10 mg dose, at room temperature. The adsorption rate of Pb²⁺ ions conformed to the pseudo-second-order (PSO) kinetics, exhibiting a rate constant of about 6 × 10⁻⁴ g mg⁻¹. min⁻¹, an initial adsorption rate (h₀) of 5.12 mg. g⁻¹ min⁻¹, and a half-life of ≈ 19 min. The elemental mapping, EDS, and FT-IR investigations confirmed that the Pb²⁺ ions adsorption by electrostatic interaction with the adsorbent’s –OH, –NH₂, and –COOH functionalities. After four rounds of recycling, the composite maintained good stability and performance, with an adsorption efficiency of approximately 86.9%. The green Y₂O₃@Chitosan demonstrated good regeneration and reuse for Pb²⁺ ions over four cycles without loss of adsorption competence, which was essential for an effective adsorbent.