Journal of Polymers and the Environment最新文献

To address the growing demand for biodegradable materials with superior reflective properties across various applications, poly(vinyl carbazole) (PVK), synthesized via radical polymerization, was melt-blended with biodegradable poly(butylene succinate) (PBS). The properties of the resulting composites were comprehensively investigated. The findings indicate that PVK and PBS interact through intermolecular forces. The incorporation of PVK did not affect the crystalline structure of PBS. However, the thermal decomposition temperature of the composite increased, and its thermodynamic properties were enhanced, despite a decrease in crystallinity. Notably, the introduction of PVK significantly improved the reflective performance of the composite. When the addition of PVK reached 5%, the water contact angle of the composite measured 100°, while the water vapor transmission rate was recorded at 14.72 [g·(m²·d)⁻¹]. The degradation rate over a period of six months was found to be 40.09%, and the reflectance was determined to be 92.91%. At this concentration, the effects of pepper color, fruit length, capsaicin content, capsanthin levels, peroxidase activity, and malonaldehyde content were also observed to be most significant. This indicates its potential as an environmentally friendly material for agricultural reflective films.

The synthesis of a tropoelastin-based polypeptide (PP), poly(AAGVP) (where A denotes Alanine, G for Glycine, V for Valine, and P for Proline), is performed using a solution-phase approach. The miscibility of PP and polyvinyl alcohol (PVA) is examined in various ratios to develop membranes for suitable biomedical applications. Miscibility in the solution phase was evaluated using viscometric parameters (K_H, ∆[η]_m, ∆B, μ, α, β, ΔK as proposed by Huggins, Garcia, Chee, Sun, Jiang, and Han, individually), indicating that PVA is miscible with PP up to 60% of PP at 25 °C. Viscosity increased with polymer concentration, being higher in PVA-rich systems but decreasing with increasing PP content. Intermolecular interactions between PP and PVA were confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and atomic force microscopy (AFM). Thermal stability of the blends, assessed by thermogravimetric analysis (TGA), showed improvements compared to pure PP. In vitro assays demonstrated α-amylase inhibition with IC₅₀ values of 0.81–0.85 µg, outperforming the standard inhibitor acarbose (1.22 µg). Enzyme kinetics (K_m and V_max) determined from Michaelis–Menten and Lineweaver–Burk plots confirmed this activity. These findings suggest that PP–PVA blends may be suitable candidates for biomedical applications.

Pectin and gelatin are used in skin tissue engineering applications due to their excellent biocompatibility; however, the low mechanical properties limit their functionality. To address this, we developed a nanocomposite system by incorporating tannic acid-derived carbon dots (TCDs) into a pectin-gelatin scaffold to enhance its physicochemical and biological performance for skin tissue engineering. Tannic acid was used to synthesize carbon dots via an environmentally benign hydrothermal method. Physical, chemical, and optical characterizations confirmed the successful synthesis of nanoparticles with a mean hydrodynamic diameter of 9.7 ± 1.27 nm and a Zeta potential of -20.5 ± 1.43 mV. Optical analysis confirmed the photoluminescent features of the nanoparticles, with peak emission observed at 431 nm under excitation at 345 nm. The scaffolds were synthesized through a freeze-drying process, and SEM imaging confirmed their highly porous structure. The influence of TCD incorporation on the mechanical, antioxidant, and biocompatibility properties of the scaffold was evaluated. Mechanical and thermal assessments revealed significant enhancements in tensile strength and thermal stability with the addition of 3% (w/w) TCDs. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay of the scaffolds showed up to 71.28 ± 2.83% free radical scavenging activity. The scaffolds demonstrated favorable biocompatibility on L929 fibroblasts, as evidenced by MTT and 4′,6-diamidino-2-phenylindole dihydrochloride (DAPI) assays, along with improved collagen production in Sirius Red staining and enhanced cell adhesion and migration behaviors. Overall, these findings indicate that TCD-reinforced pectin/gelatin scaffolds provide a sustainable and effective platform for skin tissue regeneration and wound healing applications.

Polyhydroxyalkanoates are a microbial storage polymer that presents similar characteristics to plastics, therefore are usually referred to as bioplastics. The key enzyme involved in the synthesis of polyhydroxyalkanoates is called PHA synthase, but it is always forming a synthesis cassette of three to five enzymes. In this work, we present a novel class III polyhydroxyalkanoate synthesis cassette identified using a sequence-based metagenomics approach. From two metagenomes from dairy industries stabilization ponds, we found four complete synthesis cassettes. One of them was successfully cloned into Escherichia coli CGSC: 6576, a bacterial strain able to grow in lactose and whey permeate, a by-product of dairy industries that represent an environmental risk. This recombinant strain grown in lactose was able to accumulate nearly 40% of dry weight as insoluble material identified by Fourier Transform Infrared Spectroscopy (FT-IR), Gas Chromatography with Flame Ionization Detection (GC-FID) and characterized by Nuclear Magnetic Resonance (NMR) as poly(3-hydroxybutyrate), one of the main polyhydroxyalkanoates commercially used. This research presents the complete process, from the identification of novel enzymes from uncultured microorganisms to the synthesis at laboratory scale of compounds of industrial interest.

Treatment of wound infections has been a matter of concern due to the emergence of antimicrobial resistance (AMR) in Pseudomonas aeruginosa (PA). As an alternative to antibiotics, phage therapy has proven to be an effective strategy to combat AMR. The present study aimed to fabricate PA phage (PAΦ)-gentamicin (GeN)-loaded dressing made from chitosan and alginate, to thwart wound infections associated with PA. Various chitosan-alginate (CA) scaffolds (1 C:1 A/1 C:3 A/3 C:1 A) were prepared by physical crosslinking and subjected to parametric analysis for screening, followed by functionalizing using PAΦ-GeN combination. The findings revealed that 1 C:1 A dressing exhibited high swelling index (1887%), protein adsorption ability (845.8 µg.cm^− 2), and in vitro biodegradability within 7 days. FTIR spectroscopy and thermogravimetric analysis supported biophysical characterization and electron microscopy revealed microporous structure of the dressing. Functionalized CA dressings demonstrated broad-range antibacterial potential against standard strains of Escherichia coli, Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, and clinical strains of PA, while displaying a biocompatible/non-allergenic nature. The therapeutic potential of functionalized CA dressing was further validated in vivo using a thermal injury murine model infected with PA. Topical application of PAΦ-GeN-loaded CA dressing significantly lowered bacterial burden on day 3 post-infection (p.i.) and completely eradicated pseudomonal infection by day 21 p.i. Furthermore, the functionalized CA dressing significantly enhanced skin re-epithelialization and resulted in complete wound closure in BALB/c mice on day 21 p.i. Overall, the present study reinforces the application of functionalized wound dressings as promising alternative to traditional wound care products for management of skin infections.

Graphical Abstract

Supramolecular crystalline structures were developed in films prepared from blends of a bio-based waterborne polyurethane (WBPU) based on castor oil/tartaric acid (CO-TA) with two different WBPUs synthesized from polycaprolactone diol (PCL) and dimethylol-propionic acid (PCL-DMPA) or TA (PCL-TA). Partial crystallization of the PCL segments generated topologies that strongly affected the final properties of the films. Depending on the internal emulsifier used in the synthesis of the PCL-based WBPUs and its proportion in the blend, the crystalline structures differed, resulting in lamellar, dendritic, or fiber-like networks. Several techniques were employed in the study: differential scanning calorimetry (DSC) to investigate the crystallization kinetics of the blends; optical and confocal microscopies to identify the topologies; positron annihilation lifetime spectroscopy (PALS) to correlate crystallinity with the mean nanohole volume, and dynamic mechanical analysis (DMA) to characterize the mechanical properties of the films. The crosslinked network from the CO-TA based WBPU and the microphase separation in the blends led to constrained crystal growth, resulting in distinct topologies. The work presents a novel approach to generate supramolecular structures, which had a positive effect on the films properties. The relationship between crystallinity and free volume, as measured by PALS, is also analyzed in terms of chain mobility.

Graphical Abstract

Polyesters and thermoplastic polyurethanes (TPUs) based on polyesters, as biodegradable and eco-friendly synthetic polymers, were the focus of research in recent years with promising for results for tissue engineering (TE) applications. Among the commercially available polyesters, the potential of the semi-crystalline poly (butylene succinate) (PBS) as polyols was not explored in depth. In this regard, we synthesized a PBS-diol oligomer through esterification between butylene glycol and succinic acid; the oligomer was characterized using NMR analysis. It was subsequently used as polyol for the catalyst- free synthesis of TPUs using hexamethylene diisocyanate (HDI). The FTIR results revealed successful completion of prepolymerization reaction after 2 h in the absence of toxic tin- based catalyst. The TPUs possessed high elastic modulus ((:E)) due to high PBS crystallinity. Incorporating CeO₂ nanoparticles, as an antioxidant, into the TPU with HDI: PBS-diol molar ratio of 4:1 resulted in an unprecedented rise in (:E) from 49.0 to 186.5 MPa once 0.25 wt% CeO₂ was used due to its ideal dispersion and its possible role as a nucleating agent. CeO₂ increased PBS crystallites’ thermal stability through disrupting hard domains and acting as a nucleating agent for soft segment. MTT results of the nanocomposites also revealed promising results.

Hepatic cancer remains one of the most difficult conditions to cure, particularly when it comes to detecting and eliminating malignant metastases. To overcome hepatic cancer, various strategies have been implemented in respect to targetability and safety concern. In this study, the anticancer agent quercetin (QU) was effectively encapsulated with biocompatible polymer chitosan (CS)-hyaluronic acid (HA) to improve its poor water solubility as well as dual targetability. The resulting QU-loaded nanoparticles (QU-NPs) were formulated using CS, and HA were employed as a capping and targeting agent, and lactoferrin was added to improve drug bioavailability and targetability as well. The synthesized NPs were characterized using zeta potential analysis, particle size analysis, HR-TEM spectroscopy. The in vitro safety of QCHL-NPs was confirmed through toxicity assays on HepG2 cells. In vitro cytotoxicity data showed that QCHL-NPs required significantly lower concentrations than free QU to achieve significant inhibition 50% (IC₅₀ − 10µM in 24 h and 1 µM in 48 h) of proliferation of HepG2 Cells (p < 0.01). In vivo animal study treatment with QCHL-NPs also significantly reduced antioxidant levels like TBARs (p < 0.01) and PC (p < 0.01) levels, while treatment with QCHL-NPs by increase caspase-3 (p < 0.001) analysis revealed apoptosis at the molecular level. Notably, this study successfully was synthesized QU-loaded CS nanoparticles with enhanced QU loading. The final formulation, Lf-coated, HA-capped CS NPs loaded with QU (QCHL-NPs), showed the dual targetability and antitumor efficacy compared to free QU.

This study posed the fabrication and evaluation of a novel antibacterial material composed of HKUST-1(a copper-based metal–organic framework, MOF) incorporated into a chitosan (CS) dried hydrogel disc. The CS/HKUST-1 dried hydrogel disc was synthesized using varying copper ion (Cu²⁺): trimesic acid (TMA) and CS: HKUST-1 weight ratios to optimize antimicrobial efficacy against a broad spectrum of pathogenic microorganisms. The prepared dried hydrogel disc was characterized and compared with a pure CS dried hydrogel disc. Results demonstrated homogeneous dispersion of HKUST-1 crystals within the CS dried hydrogel matrix, with the BET surface area increasing from 9.5 m²/g (pure CS dried hydrogel) to 69.8 m²/g for CS/HKUST-1. The Fourier-transform infrared spectroscopy (FT-IR) confirmed the incorporation of HKUST-1 crystal within the CS dried hydrogel matrix, and the X-ray diffraction (XRD) analysis shows an increase in crystallinity upon increasing the HKUST-1 ratio in comparison with the pure CS dried hydrogel disc. The synthesized CS/HKUST-1 dried hydrogel disc showed antibacterial activity against both Gram-positive (Staphylococcus aureus, Enterococcus faecalis), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and the fungal strain Candida albicans. As expected the CS/HKUST-1 dried hydrogel disc with a Cu²⁺:TMA ratio of 2:1 and a CS: HKUST-1 ratio of 10:10 exhibited the most potent antimicrobial activity. The CS/HKUST-1 dried hydrogel disc exhibited the slow release of copper ions. Notably, this dried hydrogel disc demonstrated strong antimicrobial performance, represented by the low values for both the minimum inhibition concentration (MIC) and the minimum bactericidal concentration (MBC). The enhanced antimicrobial performance is attributed to the synergistic interaction between the biopolymeric matrix and the porous MOF structure, which facilitates sustained Cu²⁺ release and effective disruption of microbial membrane. Overall, these findings highlight the potential of CS/HKUST-1 dried hydrogel discs as promising candidates for advanced antimicrobial materials in biomedical applications.

In this study, we incorporated Astragalus polysaccharide (APS) and MXene (Ti₃C₂T_x) into regenerated silk fibroin (RSF) to fabricate three-dimensional porous scaffolds via freeze-drying. By systematically varying the APS content while keeping the MXene content constant, we achieved enhanced mechanical properties and multifunctionality. The swelling ratio, hydrophilicity, and protein adsorption of the composite scaffolds increased with APS content, while porosity decreased. APS incorporation promoted β-sheet formation, and MXene imparted photothermal properties, enabling a temperature rise to 47 °C under 640–660 nm irradiation for 12 min. The composite scaffolds also showed high antioxidant activity (93% DPPH scavenging) and excellent hemocompatibility (< 2% hemolysis). Compared to the RSF scaffold, the composite scaffolds exhibited a 3.36-fold increase in compressive modulus (6.93 MPa) and a 1.96-fold increase in compressive strength (4.04 MPa) at an APS/RSF mass ratio of 0.2:1. In vitro studies revealed that optimal APS concentrations significantly enhanced biocompatibility by promoting the proliferation and migration of MC3T3-E1 and endothelial cells. For MC3T3-E1 cells, the optimal APS/RSF mass ratio was 0.16:1, while for endothelial cells, it was 0.2:1. Overall, this study demonstrates the potential of APS and MXene incorporation into RSF scaffolds for enhanced tissue engineering applications.