Journal of Polymers and the Environment最新文献

Polylactic acid (PLA) is widely used in additive manufacturing but suffers from low toughness, poor hydrolytic stability, and limited corrosion resistance, restricting its long-term use in marine or humid environments. This study aims to overcome these limitations by investigating the combined effects of printing orientation and PU/CNT nanocomposite coating on the mechanical durability and shape memory performance of 3D-printed PLA exposed to a 3.5 wt% NaCl solution, simulating marine conditions. PLA specimens with raster angles of 0°, 45°, and 90° were fabricated by fused deposition modeling (FDM) and coated with a polyurethane/carbon nanotube (PU/CNT) composite to enhance interlayer strength and environmental resistance. The PU/CNT coating effectively mitigated saline-induced degradation, improving tensile, impact, and flexural strength by up to 28% and maintaining over 80% of the initial strength after 21 days of immersion. Moreover, the coated PLA exhibited a shape recovery ratio of ~ 91%, compared to 82% for uncoated samples, confirming improved functional stability. These findings demonstrate that PU/CNT coatings successfully address the key mechanical and environmental limitations of PLA, providing a viable route for the reliable use of PLA-based composites in marine engineering, adaptive smart structures, and biodegradable biomedical sensors.

Researchers have been attentive in modifying the inherent properties of biopolymers by incorporating nanocarrier schemes, involving metal nanoparticles into the matrix to achieve higher potentials. Herein, fabricated in situ generation of silver nanocomposites (AgNC) NC1, NC3, and NC5 using different concentrations of AgNPs using vegetal carboxy methyl chitosan (CMCs) and Curcuma longa debranched starch, which facilitated the formation of AgNC films. UV–visible spectroscopy revealed surface plasmon resonance peaks at 413, 404, and 403 nm for NC1, NC3, and NC5, respectively, confirming the formation of AgNPs. XRD analysis demonstrated characteristic silver peaks at 2θ = 31.94°, 37.82°, and 45.92°, indexed to the (101), (111), and (200) planes, respectively and showed the plane of face-centered cubic Ag. AFM revealed that the average roughness (Ra) increased from 3.29 nm in NC0 to 42.33 nm in NC5. SEM-EDX revealed a rough surface and successful incorporation of Ag (up to 3.14 wt% in NC5), while TEM confirmed spherical AgNPs morphology with an average particle size of 24.42 ± 9.04 nm. XPS analysis further verified the presence of Ag, C, O, and N with high-resolution peaks matching Ag and Cs elemental states. TGA showed improvements in thermal stability: NC5 exhibited lower weight loss (8.61% between 326 and 600 °C) than NC0 (16.70%). The microbial efficacy was evaluated against Gram-positive, Gram-negative bacteria, and fungi. The NC5 films exhibited significant inhibition zones against S. aureus (6–9 mm), E. coli (8–10 mm), and Candida albicans (6–9 mm). MIC values for NC5 ranged from 0.025 to 0.2 cm²/mL for all the tested pathogens. The NC5 film reduced S. aureus biofilm cell counts from 10,747 ± 592 (control) to 4,416 ± 348, with biofilm cell viability decreasing from > 98% to 45–55%. In vitro release studies of Ag ions were performed at 37 °C for 36 h. Due to its improved performance, the fabricated nanocomposite films could be suitable for active food packaging, reducing environmental impacts and ensuring food safety, and should be converted into nanomedicine to meet future biomedical requirements.

This study focuses on the novel investigation of the individual and combined effects of fucoidan, ulvan, and carrageenan on growth parameters, immune responses, and digestive and antioxidant enzyme activities in common carp, emphasizing the simultaneous use of these three polysaccharides. A total of 405 common carp (50.27 ± 1.39 g) were divided into nine treatment groups: control (CTRL); fucoidan (F 0.5% and 1%); ulvan (U 0.5% and 1%); carrageenan (K 0.5% and 1%); and a combination of all three (FUK 0.5% and 1%). The results indicated that the F1, U1, K1 FUK0.5 and FUK 1% treatment significantly enhanced final weight, weight gain and specific growth rates while decreasing the feed conversion ratio compared to CTRL. Sulfated polysaccharides did not significantly affect hemoglobin and hematocrit levels; however, only the FUK1% group showed a significant increase in white and red blood cell counts compared to the CTRL. Immune parameters, including serum C3, serum and mucus lysozyme, and immunoglobulin levels, increased notably across various treatments. Expression of IL-1β decreased significantly in the F, U, K, and FUK 1% groups, while IL-10 expression increased in all treated groups. Digestive enzymes such as α-amylase, lipase, and trypsin showed remarkable increases in most treatments compared to the CTRL. Additionally, serum antioxidant parameters, including superoxide dismutase (all doses except F 0.5%, U 0.5%, and K 0.5%) and catalase (all doses except U 0.5% and K 0.5%), showed significant increases relative to the CTRL. Overall, these sulfated polysaccharides, especially FUK 0.5% and FUK 1%, positively influenced growth, immune function, digestive efficiency, and antioxidant activity in common carp.

Mucosal drug delivery offers an attractive approach for localized and systemic therapy while bypassing first-pass metabolism; however, its success is often hindered by poor drug permeability, rapid clearance, and low bioavailability. In this study, we developed a sustainable cannabidiol (CBD)-loaded nanocarrier system based on poly(D, L-lactide-co-glycolide) (PLGA) nanoparticles surface-modified with chitosan (CS), a renewable biopolymer, to enhance mucosal and neurodegenerative therapeutic performance. CS-coated PLGA nanoparticles (50–2000 µg/mL) exhibited increased particle size, a positive surface charge, and improved hydrophilicity, enabling stronger mucoadhesive interactions and storage stability for at least six months. Although CS modification slightly reduced encapsulation efficiency and drug loading, it markedly improved sustained and controlled CBD release by reducing burst effects and prolonging drug retention, consistent with first-order and Higuchi kinetics. Enhanced mucoadhesion was confirmed through stronger electrostatic interactions with mucin and improved rheological behaviour, promoting longer mucosal residence time and greater bioavailability. All formulations were highly biocompatible in HT-29 cells and exhibited significant anti-inflammatory activity, with CS-modified systems showing superior nitric oxide inhibition. Remarkably, CS-modified PLGA-CBD nanoparticles demonstrated potent, dose-dependent anti-amyloidogenic activity, outperforming curcumin at low to moderate concentrations, highlighting their promise as multifunctional, environmentally responsible nanocarriers for mucosal drug delivery and neuroinflammatory disease management.

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Near-infrared (NIR)-responsive drug delivery systems offer precise spatiotemporal control for targeted cancer therapy with minimal invasiveness. Here, we report the design of magnetic/NIR-responsive multilayer microcapsules via layer-by-layer assembly of biocompatible chitosan (CS) and carboxymethyl cellulose (CMC). Incorporation of magnetite (Fe₃O₄) and gold (Au) nanoparticles into the microcapsule shells enabled both magnetic guidance and efficient NIR-triggered drug release. Methotrexate (MTX), a potent anti-cancer agent, was encapsulated with a high loading efficiency (68%). Systematic studies revealed the influence of bilayer number, MTX concentration, and environmental pH on drug loading and release kinetics. In vitro drug release was studied in different pH values (5.0, 6.5 and 7.4) with and without an NIR irradiation. Drug release was faster at pH of 5.0 compared to other pH conditions; however, the overall amount of released drug was 16.4% in 35 hr. Under NIR irradiation for15 min, up to 85% of the loaded MTX was released, while less than 7% was released when incubated in the dark for the same duration. MTT assay against MCF-7 breast cancer cells confirmed the low cytotoxicity of the prepared microcapsules. Upon IR laser irradiation, a concentration-dependent rise in ROS generation was detected, verifying their strong photothermal activity. Hemolysis evaluation further demonstrated excellent blood compatibility, with negligible hemolytic effects even at the highest concentrations. Overall, the abundant functional groups in the CS/CMC multilayers and the tunable surface chemistry of the Fe₃O₄/Au core render these microcapsules a versatile platform for encapsulating various chemotherapeutic agents, with combined pH- and laser-responsive behavior suitable for targeted and minimally invasive cancer therapy.

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Polysaccharide hydrogel films made of chemically crosslinked carboxymethyl cellulose (CMC) were made and characterized to investigate the effect of synthesis temperature on reaction kinetics and material properties. Similar hydrogels have shown potential use in drug delivery, food packaging, and other applications. Synthesis temperature and polymer/crosslinker ratio are shown to significantly effect the properties of the resulting films making these useful tools for tuning the film properties to suit the desired application. CMC was chemically crosslinked with ethylene glycol diglycidyl ether (EGDE) in aqueous solution at synthesis temperatures between 25 °C and 60 °C and with different CMC/EGDE ratios between 0.47 and 1.42. In-situ rheological measurements were made during the cross-linking reaction to track both the kinetics and final mechanical properties of the hydrogels. Gelation time, rate of gelation, yield strain, elastic modulus, and elongation at break all showed a significant dependence on the synthesis temperature, and ratio of CMC/EGDE. The Flory theory of rubber elasticity was used to estimate the density of crosslinks and porosity of the hydrogels, and FTIR spectroscopy measurements were used to confirm the observed trends. These results indicate the presence of an ‘optimum’ synthesis temperature and CMC/EGDE ratio for the formation of strong, thin films.

This study examines the extreme halophytic plant Salicornia neei Lag., found on the Chilean Pacific coastline, as a novel and sustainable source of highly functional polysaccharides. Polysaccharide extraction was performed using a green approach in water under mild conditions, thereby significantly minimizing energy consumption. Comprehensive characterization revealed an arabinose pectic polysaccharide (36 kDa, 34% methylation). Notably, acetylated units, constituting 25% of the polysaccharide structure, were detected in any Salicornia plant extract for the very first time. The extract demonstrated outstanding emulsification activity, achieving an impressive emulsion index of above 70% with a concentration of just 1% across five diverse edible oils (corn, canola, avocado, sunflower, and sesame). This superior performance, likely attributed to the detected acetyl groups, positions it as a potent, natural, and clean-label alternative to conventional, often synthetic, emulsifiers. Furthermore, the extract exhibited remarkable antioxidant capacities (89.47% DPPH, 71.64% ABTS, 45.40% hydroxyl radical scavenging, and 98.56% ferrous ion chelation), as well as significant antimicrobial activity against B. cereus and R. eutropha. Notably, the extract showed no cytotoxicity against healthy human fibroblast cells, confirming its safety, while displaying promising selective antitumoral activity (IC₅₀ = 910 µg/mL; SI = 3.89) against colon cancer cells (HCT-116). Overall, these findings strongly suggest that the Salicornia neei from the Pacific Ocean represents a unique source of water-extractable polysaccharides, whose demonstrated superior biological activities—including groundbreaking emulsification, robust antioxidant and antimicrobial effects, and selective anticancer properties—collectively underscore its multifunctional potential as an innovative ingredient for diverse food, nutraceutical, and pharmaceutical applications.

Plant-derived polysaccharides have recently become a prominent material because of their promising biological activities. In this study, Curcuma longa debranched starch nanoparticles (STNPs) were synthesized using a nanoprecipitation method. The characterization of the synthesized STNPs was done by using various techniques. The SEM and TEM results demonstrated that the STNPs showed a spherical shape with a smooth surface with a range of 105–195 nm in size, and showed a zeta potential of −20.7 ± 4.66 mV. The STNPs showed free radical scavenging activity with IC₅₀ value of 48 ± 5 µg/mL, and 24.32 ± 2.14 µg/mL for DPPH and ABTS free radical scavenging assays, respectively. The hemocompatibility of STNPs showed negligible toxicity. The STNPs exhibited anticancer activity against HepG2 cells (human hepatocellular carcinoma cells) (IC₅₀ of 304 ± 25 µg/mL) in a dose-dependent manner. Moreover, STNPs exhibited antibacterial activity against Corynebacterium diphtheriae (6 ± 0.32 mm), Salmonella typhi (2 ± 0.1 mm), and Escherichia coli (4 ± 0.2 mm) at a 200 µg concentration, and the outcome was observed from the SEM study of bacterial membrane integrity. Moreover, STNPs at 400 µg showed biofilm inhibition of 42% and 56% for E.coli and C.diphtheriae, respectively. In conclusion, STNPs exhibited substantial antioxidant, antibacterial, antibiofilm, and anticancer activities. Collectively, these results collectively suggest that STNPs have diverse functions of, showcasing their potential as antioxidants, anticancer agents, antibacterial agents and could be useful in biomedical applications.

Bakelite is a phenol–formaldehyde thermoset with exceptional thermal stability and is an environmentally persistent material for which viable recycling methods are lacking. Elemental sulfur, an overproduced petroleum refining byproduct, similarly accumulates in large stockpiles. We report a one-pot, 100% atom economical thiocracking strategy to upcycle intractable Bakelite waste into a thermally processable composites (BLS₉₀) via reaction of Bakelite with molten sulfur at 230 °C. Model compound studies reveal the effective breakdown of the Bakelite structure via C–C and C–O s-bond scission with concomitant benzylic S–C bond formation, leading the crosslinking via oligo/polysulfur catenates. The resulting composite exhibits a glass transition at − 36 °C, a melting transition at 118 °C, and decomposition onset at 235 °C. BLS₉₀ demonstrates a compressional strength of 27 ± 2 MPa, exceeding that required for ordinary Portland cement building foundations (17 MPa), and flexural strength of 4.9 ± 0.6 MPa. These findings demonstrate that thiocracking enables effective partial replacement of the thermally intractable C–C crosslink network with thermally reversible sulfur catenate crosslinks. This process yields a mechanically robust and thermally reprocessable material from the otherwise non-recyclable thermoset. This approach offers a dual waste-mitigation pathway for Bakelite and surplus elemental sulfur, producing composites suitable for structural applications while advancing the sustainable management of polymer and industrial sulfur waste streams.

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