Journal of Polymers and the Environment最新文献

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.

Graphical Abstract

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.

Graphical Abstract

This work investigates the molecular interaction between chitosan, an effective and eco-friendly biopolymer, and crude oil components within petroleum emulsions. This mechanistic investigation combines 2D TD-NMR relaxation and computational modeling to understand chitosan’s role as an adsorbent and demulsifier for applications in environmental remediation. We applied a medium molecular mass chitosan to a series of six petroleum emulsions, spanning a representative range of medium and heavy crude oils (viscosities from 32.52 to 182.07 mm².s^-1 at 20 °C). The 2D D-T₂ correlation maps were generated using the PFG-CPMG (Pulsed Field Gradient-Carr-Purcell-Meiboom-Gill) sequence to resolve the changes in oil and water mobility following chitosan addition. The key result is the observation of a characteristic shift in the diffusion coefficient (D) and transverse relaxation time (T₂) of the oil component upon chitosan introduction. This shift provides direct evidence of the molecular interaction and the disruption of the emulsion stabilizing film. Furthermore, molecular modeling confirms strong water binding, complementing the TD-NMR findings. Overall, the study successfully demonstrates the utility of TD-NMR and molecular dynamics for mechanistic assessment, providing crucial, direct insight into the demulsification role of chitosan within petroleum emulsions.

This study determined the cloud point temperatures of a series of poly(2-hydroxypropyl acrylate) (PHPA) copolymers prepared by introducing various acrylamide derivatives using turbidimetry. This study aims to demonstrate the tunability of the cloud point temperatures of HPA-based copolymers by changing the composition of the acrylamide derivative comonomers. N-isobutoxymethyl acrylamide (IBMAAm), N-(3-methoxypropyl)acrylamide (MPAAm), acrylamide (AAm), N-(2-hydroxyethyl)acrylamide (HEAAm), and methacrylamide (MAAm) were used as comonomers to obtain copolymers of PHPA and acrylamide derivatives with different compositions. The cloud point temperatures of the copolymers based on PHPA were found to range from 7.5 to 48.2 °C, depending on the H-bond capacity and quantity of the comonomers in the copolymer. All copolymers exhibited cloud point temperatures higher than the homopolymer of HPA, except those with IBMAAm as the comonomer. Increasing the relative amount of the acrylamide derivative moiety in a copolymer type was found to increase the cloud point temperature, except for copolymers with IBMAAm. AAm and HEAAm were determined to be the most effective comonomers for elevating the cloud point temperature, possibly due to their hydrogen bond capacities and superior solubility in an aqueous medium.

Conventional polymer flooding agents, including commercial biopolymers like xanthan gum, may fail under harsh reservoir conditions due to thermo-oxidative chain scission and mechanical degradation. To bridge this gap, we introduce a novel, eco-functionalized biopolymer derived from Pseudomonas atacamensis M7D1 and functionalized with heavy metal powders from recycled printed circuit boards (PCBs) for enhanced oil recovery (EOR). This functionalization creates stable coordination complexes that act as protective sites, fundamentally enhancing molecular stability. Under extreme simulated reservoir conditions (85°C, 3wt. % NaCl), a 0.5wt. % PCB-biopolymer solution exhibits significant colloidal stability and maintains over 95% of its initial viscosity over 24 hours, directly demonstrating mitigation of the chain scission failure that plagues unmodified biopolymers. Microfluidic visualization in heterogeneous porous media reveals optimized flooding patterns and suppressed viscous fingering, a consequence of the resilient, self-healing viscoelastic character confirmed by a persistent gel-like structure (G’ > G’’) in oscillatory rheology. The 0.5wt. % biopolymer solution delivered 43.6% ultimate oil recovery at ambient temperature and retained strong performance (41% recovery) at 85 °C. Importantly, a 1wt. % solution achieved nearly 4% greater incremental oil recovery than water flooding (22% vs. 17.8%) under a monovalent NaCl salt and high temperature conditions. Consequently, this work establishes metal-functionalized biopolymers as sustainable, high-performance alternatives by uniquely combining extreme salinity/temperature tolerance, colloidal resilience, and efficient pore-scale flow control through deliberate molecular engineering.

Indole-3-acetic acid (IAA) is a widely used plant growth regulator; however, its rapid environmental degradation limits practical applications. Encapsulation in biopolymer matrices offers a promising strategy to enhance its stability. V-type starch, a single-helical amylose structure, can form inclusion complexes with small molecules. In this study, V-type starch was synthesized from maize starch using an antisolvent precipitation method and employed as a delivery system for IAA. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), near-infrared (NIR) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. The IAA release profile, photostability, bioactivity in tomato plants, and biotoxicity in Artemia salina were evaluated. IAA release from the complex was pH-dependent: complete (100%) release was achieved after 48 h at pH 3.0, 96 h at pH 5.0 and 120 h at pH 7.0. After 240 min of UV irradiation, the starch-IAA complex exhibited only 18% degradation, compared to 100% for technical IAA. In tomato plants, the starch-IAA complex at 500 µg/mL enhanced growth by increasing leaf number and root biomass, whereas at 1000 µg/mL, it inhibited growth similarly to technical IAA. Biotoxicity tests in Artemia salina showed that at 1000 µg/mL, free IAA caused 60% mortality, while the starch-IAA complex and V-type starch caused only 9.9% and 6.5%, respectively. These results suggest that V-type starch enables controlled IAA release while reducing toxicity, highlighting its potential as a safe and effective delivery system for agricultural applications.

This study investigates the kinetic modeling of castor oil epoxidation via the Prilezhaev reaction using in situ generated peracetic acid, with a focus on optimizing the process through Particle Swarm Optimization (PSO). Experimental procedures involved the use of ZSM-5/H₂SO₄, with reactions monitored by titration, FTIR, NMR, and GPC analysis. FTIR confirmed successful epoxidation through the appearance of characteristic oxirane peaks at 852 cm⁻¹ and the disappearance of alkene bands. NMR spectra showed reduction of olefinic (5.2–5.4 ppm) and allylic protons (1.8–2.0 ppm), and emergence of epoxide ring signals (3.6–3.8 ppm). GPC revealed a drop in weight-average molecular weight (Mw) from 9732 to 1013 g/mol and polydispersity index (PDI) from 7.66 to 1.51, confirming chain scission during epoxidation. The reaction was modeled through a system of second-order differential equations representing peracid formation, epoxide synthesis, and degradation. Two models were compared—one spanning 0–60 min (including reversible reactions) and another from 30 to 60 min (unidirectional). PSO achieved an R² of 0.52 for the full model and R² of 0.98 for the 30–60 min range. The unidirectional model demonstrated superior predictive accuracy, suggesting that inclusion of reversibility introduced noise, especially during early reaction stages. This highlights PSO’s limitations in handling reversible systems and supports the use of simplified forward-reaction kinetics, focusing on epoxide formation and ring-opening steps while excluding the reverse formation of peroxy acid. This approach improves model performance in epoxidation processes while still benefiting from the fast convergence of the PSO algorithm compared to other algorithms.