Journal of Polymers and the Environment最新文献

Bio-based composite films offer a sustainable alternative to synthetic packaging materials due to their biodegradability and functional versatility. In this study, a biodegradable film was developed using gelatin (GA), lignin (LG), and tannic acid (TA), for applications in food packaging and seed preservation. Films were prepared by fixing GA and varying LG and TA, on a weight/weight (w/w) basis relative to GA. The optimized formulation (LGT68) exhibited a tensile strength of 7.59 ± 0.58 MPa, and elongation at break (EAB) of 158.54 ± 15.68%. Scanning electron microscopy (SEM) revealed a dense fibrillar matrix with uniformly dispersed spherical agglomerates, attributed to LG–TA interactions within the GA matrix. Fourier-transform infrared spectroscopy (FTIR) confirmed strong hydrogen bonding. The film also demonstrated complete ultraviolet (UV) blocking, improved hydrophobicity with a water contact angle of 89.4 ± 0.7°, and significant antimicrobial activity with a 23 mm zone of inhibition against Staphylococcus aureus (S. aureus). Real-time application trials using raw beef and mushroom for packaging and seeds of Momordica charantia for coating confirmed the film’s effectiveness in extending shelf life. These results highlight the potential of LGT films as sustainable and multifunctional materials for active food packaging and seed protection applications.

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Ultraviolet radiation exerts detrimental effects on skin health, necessitating the use of sunscreen products for effective protection. However, conventional sunscreens encounter limitations due to their susceptibility to photo-instability, skin irritation, and environmental impact. The primary objective of this study is to circumvent these limitations by substituting plastic microspheres and conventional sun protection agents with enzyme-modified natural porous corn starch microspheres and Xanthoceras sorbifolium bunge (X. sorbifolia) oil composites. The average particle size of enzyme-modified porous corn starch microspheres was 13.24 μm, and they possess a porous structure, enabling adsorption and shielding effects. The SPF value of the sunscreen product formulated by substituting an equivalent quantity of UV shielding agent TiO₂ with porous microspheres was 23.75 ± 0.15, which was comparable to the TiO₂ sunscreen product. Following the reduction of the UV absorber in the sunscreen product by half and the incorporation of microspheres and the X. sorbifolia oil composite, the SPF value of the product retained a higher level compared to its predecessor (30.5 ± 0.07 vs. 16.44 ± 0.02). When this natural composite synergistically worked with conventional UV absorbers benzophenone-3 (BP-3) and ethylhexyl methoxycinnamate (EHMC), the photostability of BP-3 and EHMC was effectively enhanced. Embryotoxicity studies conducted on zebrafish demonstrated that natural porous starch and X. sorbifolia oil exhibited reduced toxicity compared to conventional sunscreen agents, particularly at elevated concentrations. These findings suggest novel ideas for the development of safe and effective sunscreen products in the future.

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Mesoporous silica nanoparticles (MSNs) have emerged as promising carriers in drug delivery systems due to their high surface area, tunable pore structure, excellent chemical stability, and biocompatibility. However, their practical application is often hindered by premature drug leakage and limited targeting capability. To address these challenges, a hybrid nanocarrier was developed by coating MSNs with a lipid bilayer (ML) and subsequently with a chitosan-polyethylene glycol-folic acid copolymer (CPF), yielding CPF-coated ML nanoparticles (MLCPF). Characterization confirmed successful layer-by-layer assembly with nanoscale size, spherical morphology, positive surface charge, and good colloidal stability. Doxorubicin (DOX) was efficiently loaded into MLCPF (DOX@MLCPF), exhibiting pH-responsive release with slower drug release at neutral pH and faster release under acidic conditions. In vitro studies showed blank MLCPF was biocompatible, while DOX@MLCPF displayed stronger anticancer activity than free DOX. Confocal microscopy revealed efficient cellular uptake of CPF-functionalized nanoparticles. These findings suggest MLCPF as a promising platform for controlled and targeted cancer therapy.

The escalating environmental challenges posed by organic dye pollution necessitate the development of efficient and sustainable remediation technologies. This study presents a novel strategy to enhance the visible-light photocatalytic performance of TiO₂ through the synthesis of hyperbranched polyglycerol (HPG)-modified nanocomposites functionalized with photosensitizers (hemin and Eosin Y (EY)). A sol-gel method was employed to graft HPG with tailored polymerization degrees and branching architectures onto TiO₂ surfaces, enabling systematic investigation of the effects of modifier content, polymer structure, and light source on photocatalytic activity. The grafted polymers significantly narrowed TiO₂’s bandgap energy (from 2.82 eV for pure TiO₂ to as low as 0.73 eV for HPG2-hemin/TiO₂), extending its light absorption to the visible spectrum. Under optimized conditions, 1% HPG5-EY/TiO₂ achieved a methylene blue (MB) degradation rate of 73.22% within 120 min of visible-light irradiation—a 2.11-fold enhancement compared to pristine TiO₂. The composite also demonstrated exceptional recyclability, retaining over 95% of its initial activity after four recycling cycles. The catalyst has exhibited excellent degradation performance in visible light compared to most of the recently reported systems. Mechanistic studies revealed that the abundant hydroxyl groups in HPG facilitated the generation of reactive oxygen species (•OH and •O₂⁻), which synergistically accelerated MB degradation. This work establishes a robust framework for designing high-performance TiO₂-based photocatalysts by leveraging polymer structural engineering and photosensitizer integration. The approach not only addresses the inherent limitations of TiO₂’s UV-dependent activity but also provides a scalable strategy for sustainable wastewater treatment under solar illumination.

Insoluble starch-chitosan foams were produced through a novel plasticization process that integrates glycerol via a post-expansion soaking and freeze-drying process. Starch foams incorporating 4% and 8% chitosan were first expanded and cross-linked using microwave heating, then soaked in a 7.5% glycerol solution, frozen, and freeze-dried to retain glycerol within the foam matrix. This process uniquely preserves the position of the glycerol in the foam by sublimating water during freeze-drying, allowing for internal plasticization without structural collapse. The resulting foams showed up to a 43% reduction in compressive modulus, yielding mechanically soft yet stable structures. Rheological characterization revealed that chitosan-starch polyelectrolyte complexation helped reduce retrogradation with the presence of glycerol. Increasing chitosan content enhanced foam integrity, while swelling behavior confirmed that both chitosan and glycerol concentrations influenced solution uptake. This study demonstrates a promising method for producing soft, insoluble, stable and retrogradation-resistant starch-based foams for a wide variety of diverse applications.

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Ulvan, a biodegradable sulfated polysaccharide from Ulva papenfussii, was obtained using hot water (neutral pH) and alkaline (pH 13) methods to evaluate how extraction conditions modulate its molecular dynamics and dielectric behavior. While compositional changes due to extraction pH are well documented, their impact on the relaxation processes and segmental mobility of ulvan remains largely unexplored. Here, we provide a comprehensive characterization of dielectric permittivity and dielectric loss over a wide frequency (10⁻²-10⁶ Hz) and temperature range (-150 °C to 150 °C), supported by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The alkaline-extracted ulvan showed a lower glass transition temperature (31.6 °C vs. 47.9 °C), higher molecular mobility, and enhanced dielectric response. In contrast, the hot water-extracted sample exhibited greater thermal stability and a more defined dipolar relaxation processes, including a β-relaxation characterized using the Havriliak–Negami model. These findings suggest that hot water-extracted ulvan is more suitable for applications like biodegradable packaging or biomedical films, while alkaline-extracted ulvan is better suited for electroactive materials such as polymer electrolytes. This study highlights the role of extraction strategy in designing ulvan-based sustainable materials. The results underscore the relevance of broadband dielectric spectroscopy as a powerful tool for guiding the design of polysaccharide-based functional materials.

The development of cushioning material with excellent resilience, high compressive strength, and sustainability is essential for engineering development, and environmental protection. In this study, we report a simple and effective method to produce poly (butylene adipate-co-terephthalate) (PBAT)/poly(lactic acid) (PLA) foams with excellent resilience and thermal stability by introducing a small amount of poly (D-lactic acid) (PDLA) through melt blending and supercritical CO₂ foaming. PDLA interacts with poly (L-lactic acid) PLLA chains to form stereocomplex (SC) crystals, which act as rheological modifiers and through tuning the PLLA/PDLA ratio, promote the formation of a rigid co-continuous PLA network within PBAT matrices. The incorporation of SC microcrystals significantly improved the mechanical strength and thermal stability of the foams compared to conventional PBAT/PLA blends that exhibit island-like morphology. The main findings include the production of foams with high cell density (~ 1 ± 0.5 × 10⁹ cells/cm³), uniform bubble size (~ 15 μm), maximum stress at 50% strain of 0.3 MPa, permanent deformation rate of less than 10%, and minimum buffer coefficients of ~ 3.0. In addition, SC crystals considerably retarded the dimensional changes at elevated temperatures, thus improving the stability of the foams. This study highlights a practical strategy for designing high-performance, biodegradable polymer foams, with potential applications in sustainable packaging and protective materials.

In this research, a Pickering nanoemulsion (PNE) coating was successfully created using carboxymethyl cellulose (CMC) and chitosan (C) combined with Pelargonium essential oil (PEO) at quantities of 0.5%, 1%, and 2%. The essential oil compounds were analyzed using GC–MS data, revealing their beneficial effects against the activities of microorganisms like Staphylococcus aureus, Escherichia coli O157:H7, Alternaria alternata, and Aspergillus flavus. Additionally, SEM images revealed that the addition of PEO to the solution enabled the Pickering chitosan (PC) particles to directly stabilize the emulsion and incorporate the oil phase into the polymer matrix, ultimately leading to the formation of oil-loaded nanocapsules. Average particle size of 147.5 d.nm, zeta potential of − 44 mV, and PDI of 0.25 indicated the successful formation of a complex with Pickering CMC-C-PEO, resulting in a stable and antioxidant-rich PNE. The physicochemical properties of fig samples were assessed over 6 days at 25 °C, including weight loss, decay percentage, Juicability, titratable acidity, pH, total soluble solids, total phenol content, total anthocyanin, and total ascorbic acid amounts. As regards the results, the highest content of total phenol (23.93 ± 1.32 mg/100 g sample), total anthocyanin content (52.04 ± 1.81 mg/100 g sample), and the lowest decay percentage (12.50 ± 12.50%) were associated with the sample coated with PNE of CMC-C-PEO 2%. In contrast, the control samples exhibited the opposite trend for these factors, respectively (17.87 ± 2.62 mg/100 g sample, 13.70 ± 1.60 mg/100 g sample, and 87.50 ± 12.50% mg/100 g sample). This study presents a novel, plant-based, PNE system that integrates natural polymers and essential oils to enhance postharvest quality and microbial safety of perishable fruits. The coating not only extends shelf life but also preserves nutritional and functional attributes, offering a sustainable alternative to synthetic preservatives.

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The development of multifunctional scaffolds with improved mechanical strength, swelling resistance, antibacterial activity and cytocompatibility is crucial for tissue engineering. In this study, chitosan–gelatin (CH GT) scaffolds were reinforced with curcumin (Cur), nano-curcumin (nCur), and PLGA-encapsulated curcumin (PLGA_Cur) to enhance physicochemical and biological properties. SEM micrographs confirmed uniform, interconnected pores with reduced pore wall disruption upon Cur incorporation. Mechanical testing revealed that the highest tensile strength and tensile modulus for CH GT nCur were observed at 34 kPa and 58 kPa, respectively. Swelling studies showed a significant reduction in equilibrium swelling ratio from ~ 675% (CH GT) to ~ 340% (CH GT_nCur), correlating with enhanced hydrogen bonding and physical crosslinking. Antibacterial assays indicated significant inhibition against S. aureus (~ 94%) and E. coli (~ 92%) for CH GT_nCur. Cytocompatibility tests showed > 85% cell viability across all formulations, with CH GT_nCur supporting superior cell attachment and cell migration capabilities compared to controls. Cur release from CH GT Cur and CH GT nCur hydrogel scaffolds resulted in antioxidant activity; however it was slightly impeded by rapid release. In the PLGA-based system, antioxidant activity is enhanced with sustained release. CH GT Cur and CH GT nCur enhanced M2 macrophage polarization (p < 0.001) compared to CH GT Cur hydrogels, which successfully decreased inflammation and oxidative stress. Notably, despite a delayed M2 response, the PLGA-encapsulated Cur system (CH GT PLGA_Cur) demonstrated sustained decrease of ROS levels and iNOS expression, suggesting extended anti-inflammatory effect. These results demonstrate the promise of CH GT-based hydrogels, particularly the PLGA_Cur system, for oxidative stress management and regulated immunomodulation in therapeutic settings.

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Recently, hydrogel films, due to their biocompatibility, high drug and encapsulation efficacy, and adjustable physicochemical features, have emerged as promising candidates for delivering therapeutics in the treatment of human cancers. Therefore, this study aimed to design dialdehyde starch-crosslinked chitosan hydrogel films modified zeolitic imidazolate framework-8 (ZIF-8) for controlled release of doxorubicin (DOX) to HeLa cancer cells. For the preparation these hydrogel films, the dialdehyde starch (DS) in different percentages was utilized to crosslink chitosan (CS) through the Schiff base imine reaction, which 5% was chosen as the optimal content for preparing CS hydrogel films with higher swelling capacity (1000% at pH 7.4 for 72 h). Then, a subsequent in-situ synthesis method was employed to grow antibacterial ZIF-8 nanoparticles on the DS-CS hydrogel films (DS-CS/ZIF-8). To elucidate the effectiveness of the DS-CS/ZIF-8 nanocomposite hydrogel films as a pH-responsive drug carrier, DOX was loaded as a model anticancer drug (97.6%) by soaking in a solution of the drug. The in-vitro DOX release study indicated a time-dependent, pH-sensitive controlled release profile (< 35% at pH 7.4 and about 90% at pH 5 over 72 h). Notably, the MTT assay demonstrated good cytocompatibility and significant cytotoxicity against the HeLa cancer cells (cell viability < 50% at 6 µg/mL) for both the DS-CS/ZIF-8 and DOX-loaded DS-CS/ZIF-8. The DS-CS/ZIF-8 showed improved antibacterial properties toward both S. aureus (MIC: 31.2 µg•mL^–1) and E. coli (MIC: 62.5 µg•mL^–1) bacteria. Based on the obtained results, the synthesized biocompatible nanocomposite hydrogel films with pH-sensitive features have the potential for use as an implantable anticancer treatment.