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1.
Sci Rep ; 14(1): 15450, 2024 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-38965403

RESUMO

Ghost fishing is a global issue that can be addressed using fishing gear materials that do not persist in the marine environment. However, for these alternatives to be widely adopted, they must meet the same mechanical specifications as current commercial materials while degrading without any negative impact. The objective of this study was to compare a conventional gillnet made of polyamide 6 (PA6) with an alternative made of poly(butylene succinate-co-adipate-co-terephthalate) (PBSAT) at three different scales: monofilament, knot, and net. While the PBSAT monofilament's strength was half that of the conventional PA6 net, knot and net losses were even more significant. This indicates a greater sensitivity of the material to the knot. Since the results between the knot and net scales were coherent, testing whole net panels is not necessary. Studying the curvature and the behaviour of the knot revealed its complex geometry and mechanical behaviour. Testing the weaver's knot is a good indicator for studying the relevance of an alternative to conventional fishing gear materials. This should be considered when developing biodegradable nets in order to reduce ghost fishing at sea.


Assuntos
Teste de Materiais , Polímeros/química , Poliésteres/química , Pesqueiros , Caprolactama/análogos & derivados , Caprolactama/química , Resistência à Tração
2.
Food Chem ; 451: 139368, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-38657518

RESUMO

A unique strategy for developing porous membrane protected micro-solid phase extraction has been provided. An electrospun composite was fabricated on the sheet of membrane. To this end, NiFe-layered double hydroxide/Nylon 6 composite nanofibers were coated on a polypropylene membrane sheet followed by folding into a pocket shape, which were then utilized as a novel extractive device to extract of organophosphorus pesticides from fresh fruit juice samples prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The fabricated hybrid composites were successfully characterized. The effective parameters on extraction performance were investigated. LODs were 0.020-0.065 ng mL-1. Excellent linearity (R2≥0.996) was observed between 0.05 and 100.0 ng mL-1. RSDs% were in the range of 3.1-5.8% (intra-day, n = 3) and 2.6-5.5% (inter-day, n = 3×3). Satisfactory related recovery values within the acceptable range of 90.7-111.2% with RSDs% below 6.7% were achieved for the analysis of real samples.


Assuntos
Caprolactama , Sucos de Frutas e Vegetais , Polímeros , Polipropilenos , Microextração em Fase Sólida , Espectrometria de Massas em Tandem , Sucos de Frutas e Vegetais/análise , Polipropilenos/química , Microextração em Fase Sólida/instrumentação , Microextração em Fase Sólida/métodos , Polímeros/química , Caprolactama/química , Caprolactama/análogos & derivados , Praguicidas/isolamento & purificação , Praguicidas/química , Contaminação de Alimentos/análise , Compostos Organofosforados/isolamento & purificação , Compostos Organofosforados/química , Compostos Organofosforados/análise , Níquel/química , Níquel/isolamento & purificação , Porosidade , Cromatografia Líquida/instrumentação , Extração em Fase Sólida/instrumentação , Extração em Fase Sólida/métodos
3.
Water Res ; 254: 121397, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38461599

RESUMO

Municipal wastewater treatment plants (WWTPs) play a crucial role in the collection and redistribution of plastic particles from both households and industries, contributing to their presence in the environment. Previous studies investigating the levels of plastics in WWTPs, and their removal rates have primarily focused on polymer type, size, shape, colour, and particle count, while comprehensive understanding of the mass concentration of plastic particles, particularly those <1 µm (nanoplastics), remains unclear and lacking. In this study, pyrolysis gas chromatography-mass spectrometry was used to simultaneously determine the mass concentration of nine selected polymers (i.e., polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(ethylene terephthalate) (PET), nylon 6, nylon 66, polyvinylchloride (PVC), poly(methyl methacrylate) (PMMA) and polycarbonate (PC)) below 1 µm in size across the treatment processes or stages of three WWTPs in Australia. All the targeted nanoplastics were detected at concentrations between 0.04 and 7.3 µg/L. Nylon 66 (0.2-7.3 µg/L), PE (0.1-6.6 µg/L), PP (0.1-4.5 µg/L), Nylon 6 (0.1-3.6 µg/L) and PET (0.1-2.2 µg/L), were the predominant polymers in the samples. The mass concentration of the total nanoplastics decreased from 27.7, 18 and 9.1 µg/L in the influent to 1, 1.4 and 0.8 µg/L in the effluent, with approximate removal rates of 96 %, 92 % and 91 % in plants A, B and C, respectively. Based on annual wastewater effluent discharge, it is estimated that approximately 24, 2 and 0.7 kg of nanoplastics are released into the environment per year for WWTPs A, B and C, respectively. This study investigated the mass concentrations and removal rates of nanoplastics with a size range of 0.01-1 µm in wastewater, providing important insight into the pollution levels and distribution patterns of nanoplastics in Australian WWTPs.


Assuntos
Caprolactama/análogos & derivados , Polímeros , Poluentes Químicos da Água , Purificação da Água , Águas Residuárias , Microplásticos , Nylons , Pirólise , Cromatografia Gasosa-Espectrometria de Massas , Austrália , Plásticos/análise , Polipropilenos/análise , Polimetil Metacrilato , Polietilenos , Poluentes Químicos da Água/química , Monitoramento Ambiental
4.
Nat Commun ; 15(1): 1217, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38336849

RESUMO

Successes in biocatalytic polyester recycling have raised the possibility of deconstructing alternative polymers enzymatically, with polyamide (PA) being a logical target due to the array of amide-cleaving enzymes present in nature. Here, we screen 40 potential natural and engineered nylon-hydrolyzing enzymes (nylonases), using mass spectrometry to quantify eight compounds resulting from enzymatic nylon-6 (PA6) hydrolysis. Comparative time-course reactions incubated at 40-70 °C showcase enzyme-dependent variations in product distributions and extent of PA6 film depolymerization, with significant nylon deconstruction activity appearing rare. The most active nylonase, a NylCK variant we rationally thermostabilized (an N-terminal nucleophile (Ntn) hydrolase, NylCK-TS, Tm = 87.4 °C, 16.4 °C higher than the wild-type), hydrolyzes 0.67 wt% of a PA6 film. Reactions fail to restart after fresh enzyme addition, indicating that substrate-based limitations, such as restricted enzyme access to hydrolysable bonds, prohibit more extensive deconstruction. Overall, this study expands our understanding of nylonase activity distribution, indicates that Ntn hydrolases may have the greatest potential for further development, and identifies key targets for progressing PA6 enzymatic depolymerization, including improving enzyme activity, product selectivity, and enhancing polymer accessibility.


Assuntos
Caprolactama/análogos & derivados , Nylons , Polímeros , Hidrólise , Polímeros/química , Poliésteres
5.
Food Chem ; 445: 138740, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38359569

RESUMO

Microplastics released from plastic-based filter bags during tea brewing have attracted widespread attention. Laser confocal micro-Raman and direct classical least squares were used to identify and estimate micron-sized microplastics. Characteristic peaks from pyrolysis-gas chromatography/mass spectrometry of polyethylene terephthalate, polypropylene, and nylon 6 were selected to construct curves for quantification submicron-sized microplastics. The results showed that microplastics released from tea bags in the tea infusions ranged from 80 to 1288 pieces (micron-sized) and 0 to 63.755 µg (submicron-sized) per filter bag. Nylon 6 woven tea bags released far fewer microplastics than nonwoven filter bags. In particular, a simple strategy of three pre-washes with room temperature water significantly reduced microplastic residues with removal rates of 76 %-94 % (micron-sized) and 80 %-87 % (submicron-sized), respectively. The developed assay can be used for the quantitative evaluation of microplastics in tea infusions, and the pre-washing reduced the risk of human exposure to microplastics during tea consumption.


Assuntos
Caprolactama/análogos & derivados , Microplásticos , Poluentes Químicos da Água , Humanos , Plásticos/análise , Polímeros , Chá , Poluentes Químicos da Água/análise , Monitoramento Ambiental/métodos
6.
J Biomed Mater Res B Appl Biomater ; 112(1): e35370, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38247254

RESUMO

Hyaluronic acid (HA) and chitosan (CS), as natural biomaterials, display excellent biocompatibility and stimulate the growth and proliferation of fibroblasts. Furthermore, nylon 6 (N6) is a low-cost polymer with good compatibility with human tissues and high mechanical stability. In this study, HA and CS were applied to modify N6 nanofibrous mat (N6/HA/CS) for potential wound dressing. N6/HA/CS nanofibrous composite mats were developed using a simple one-step electrospinning technique at different CS concentrations of 1, 2, and 3 wt%. The results demonstrated that incorporating HA and CS into N6 resulted in increased hydrophilicity, as well as favorable physical and mechanical properties. In addition, the minimum inhibitory concentration and (MIC) optical density techniques were used to determine the antibacterial properties of N6/HA/CS nanofibrous composite mats, and the results demonstrated that the composites could markedly inhibit the growth of Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. Because of its superior mechanical properties, substantial antimicrobial effects, and hydrophilic surface, N6/HA/CS at 2 wt% of CS (N6/HA/CS2) was chosen as the most suitable nanofibrous mat. The swelling, porosity, gel content, and in vitro degradation studies imply that N6/HA/CS2 nanofibrous composite mat has proper moisture retention and biodegradability. Furthermore, the N6/HA/CS2 nanofibrous composite mat was discovered to be nontoxic to L929 fibroblast cells and to even improve cell proliferation. Based on the findings, this research offers a simple and rapid method for creating material that could be utilized as prospective wound dressings in clinical environments.


Assuntos
Caprolactama/análogos & derivados , Quitosana , Nanofibras , Humanos , Quitosana/farmacologia , Ácido Hialurônico/farmacologia , Estudos Prospectivos , Bandagens , Antibacterianos/farmacologia , Escherichia coli , Polímeros
7.
J Hazard Mater ; 465: 133435, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38224639

RESUMO

Nylon-6,6 microplastics (NMPs) in aquatic systems have emerged as potential contaminants to the global environment and have garnered immense consideration over the years. Unfortunately, there is currently no efficient method available to eliminate NMPs from sewage. This study aims to address this issue by isolating Brucella intermedia ZL-06, a bacterium capable of producing a bacterial polysaccharide-based flocculant (PBF). The PBF generated from this bacterium shows promising efficacy in effectively flocculating NMPs. Subsequently, the precipitated flocs (NMPs + PBF) were utilized as sustainable feedstock for synthesizing PBF. The study yielded 6.91 g/L PBF under optimum conditions. Genome sequencing analysis was conducted to study the mechanisms of PBF synthesis and nylon-6,6 degradation. The PBF exhibited impressive flocculating capacity of 90.1 mg/g of PBF when applied to 0.01 mm NMPs, aided by the presence of Ca2+. FTIR and XPS analysis showed the presence of hydroxyl, carboxyl, and amine groups in PBF. The flocculation performance of PBF conformed to Langmuir isotherm and pseudo-first-order adsorption kinetics model. These findings present a promising approach for reducing the production costs of PBF by utilizing NMPs as sustainable nutrient sources.


Assuntos
Brucella , Caprolactama/análogos & derivados , Microplásticos , Polímeros , Plásticos , Esgotos/microbiologia , Floculação
8.
Am J Respir Crit Care Med ; 209(4): 427-443, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-37971785

RESUMO

Rationale: Microplastics are a pressing global concern, and inhalation of microplastic fibers has been associated with interstitial and bronchial inflammation in flock workers. However, how microplastic fibers affect the lungs is unknown. Objectives: Our aim was to assess the effects of 12 × 31 µm nylon 6,6 (nylon) and 15 × 52 µm polyethylene terephthalate (polyester) textile microplastic fibers on lung epithelial growth and differentiation. Methods: We used human and murine alveolar and airway-type organoids as well as air-liquid interface cultures derived from primary lung epithelial progenitor cells and incubated these with either nylon or polyester fibers or nylon leachate. In addition, mice received one dose of nylon fibers or nylon leachate, and, 7 days later, organoid-forming capacity of isolated epithelial cells was investigated. Measurements and Main Results: We observed that nylon microfibers, more than polyester, inhibited developing airway organoids and not established ones. This effect was mediated by components leaching from nylon. Epithelial cells isolated from mice exposed to nylon fibers or leachate also formed fewer airway organoids, suggesting long-lasting effects of nylon components on epithelial cells. Part of these effects was recapitulated in human air-liquid interface cultures. Transcriptomic analysis revealed upregulation of Hoxa5 after exposure to nylon fibers. Inhibiting Hoxa5 during nylon exposure restored airway organoid formation, confirming Hoxa5's pivotal role in the effects of nylon. Conclusions: These results suggest that components leaching from nylon 6,6 may especially harm developing airways and/or airways undergoing repair, and we strongly encourage characterization in more detail of both the hazard of and the exposure to microplastic fibers.


Assuntos
Caprolactama/análogos & derivados , Microplásticos , Plásticos , Polímeros , Camundongos , Humanos , Animais , Nylons , Têxteis , Poliésteres
9.
Biomater Sci ; 12(2): 335-345, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38014921

RESUMO

Oral protein delivery holds significant promise as an effective therapeutic strategy for treating a wide range of diseases. However, effective absorption of proteins faces challenges due to biological barriers such as harsh conditions of the stomach and the low permeability of mucous membranes. To address these challenges, this article presents a novel nano-in-nano platform designed for enteric protein delivery. This platform, obtained by electrospinning, involves a coaxial arrangement comprising poly(N-vinylcaprolactam) nanogels (NGs) enclosed within nanofibers of Eudragit® L100-55 (EU), a pH-responsive polymer. The pH-selective solubility of EU ensures the protection of NGs during their passage through the stomach, where the fibers remain intact at low pH, and releases them in the intestine where EU dissolves. The switchable characteristic of this nano-in-nano platform is confirmed by using NGs loaded with a model protein (ovalbumin), which is selectively released when the intestinal pH is achieved. The versatility of this nano-in-nano delivery platform is demonstrated by the ability to modify the fibers dissolution profile simply by adjusting the concentration of EU used in the electrospinning process. Furthermore, by tuning the properties of NGs, the potential applications of this platform can be further extended, paving the way for diverse therapeutic possibilities.


Assuntos
Caprolactama/análogos & derivados , Sistemas de Liberação de Fármacos por Nanopartículas , Polímeros , Ácidos Polimetacrílicos , Nanogéis , Ácidos Polimetacrílicos/química , Concentração de Íons de Hidrogênio
10.
Water Sci Technol ; 88(10): 2491-2498, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38017673

RESUMO

In this study, wet oxidation of excess sludge from the caprolactam wastewater treatment process was investigated. The effects of reaction conditions, including sludge concentration, the amount of sludge, reaction temperature and time and the oxygen supply amount, were discussed. The highest removal rates of chemical oxygen demand (COD) and volatile suspended solid (VSS) that can be attained at 78.6 and 89.3% were acquired separately under 260 °C for 60 min with an initial oxygen gas pressure of 1.3 MPa. The sludge was hydrolyzed and oxidized under hydrothermal conditions, producing small molecule organic acids, such as acetic, formic and oxalic acids, as the main products, which could be used as carbon sources for wastewater treatment. These results indicated that wet oxidation provides a favourable and feasible alternative method for the treatment of excess sludge from the coal chemical industry.


Assuntos
Caprolactama , Purificação da Água , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Oxirredução , Análise da Demanda Biológica de Oxigênio , Oxigênio
11.
Colloids Surf B Biointerfaces ; 227: 113346, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37230051

RESUMO

Novel multi-responsive drug delivery vehicles (CDs/PNVCL@HMSNs) were prepared by grafting amino-terminated poly (N-vinyl caprolactam) (PNVCL-NH2) and amino-rich carbon dots (CDs) on the surface of aldehyde-functionalized HMSNs (HMSNs-CHO) via Schiff base reaction. The CDs were prepared from L-arginine and their surfaces were rich in guanidine. Doxorubicin (DOX) was loaded into the nanoparticles to form drug loaded vehicles (CDs/PNVCL@HMSNs-DOX) and the drug loading efficiency was 58.38%. The drug release behaviors of CDs/PNVCL@HMSNs-DOX showed temperature and pH responsiveness due to the poly (N-vinyl caprolactam) (PNVCL) and Schiff base bond. The high concentration of NO released in high concentration H2O2 of tumor site could induce tumor cells apoptosis. The multi-responsive CDs/PNVCL@HMSNs are intriguing drug carriers, which combine drug delivery and NO release in one.


Assuntos
Caprolactama , Nanopartículas , Dióxido de Silício/química , Peróxido de Hidrogênio , Bases de Schiff , Sistemas de Liberação de Medicamentos , Doxorrubicina/farmacologia , Doxorrubicina/química , Portadores de Fármacos/química , Nanopartículas/química , Liberação Controlada de Fármacos , Porosidade
12.
Environ Pollut ; 329: 121684, 2023 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-37087088

RESUMO

The massive generation of synthetic textile waste has drawn considerable attention. Landfilling/incineration of textile waste has been widely made. To abate the environmental burdensome from the conventional management processes, a thermo-catalytic conversion was used for rapid volume reduction of textile waste and simultaneous valorization by recovering textile monomer in this study. Stockings were chosen as a model feedstock. Because stockings consisted of nylon with other contents, different products (caprolactam (nylon monomer), imines, cyclic dimers, and azepines) were recovered. The yield of caprolactam from the thermal conversion at 500 °C was 53.6 wt%. To selectively enhance the caprolactam yield, catalytic pyrolysis was done using γ-Al2O3 supported metal catalysts (Ni, Cu, Fe, or Co). γ-Al2O3 itself increased the caprolactam yield up to 69.0 wt% via a based-catalyzed reaction of nylon depolymerization and intramolecular cyclization. Under the presence of metal catalysts, the caprolactam yield increased up to 73.3 wt%. To offer desired feature of green chemistry, CO2 was adopted as reactive gas. Under the CO2-mediated catalytic pyrolysis, caprolactam yield was enhanced up to 77.1 wt% over Cu/Al2O3 (basis: stocking mass). Based on the net content of nylon in the stockings, the yield of caprolactam was deemed 95.3 wt%. This study proves that textile waste (stocking) and CO2 are useful resources for recovery of nylon monomer, which can reduce the waste generation with simultaneous recovery of value-added product.


Assuntos
Caprolactama , Nylons , Dióxido de Carbono , Têxteis , Metais , Catálise
13.
Metab Eng ; 77: 89-99, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36933819

RESUMO

Valerolactam is a monomer used to manufacture high-value nylon-5 and nylon-6,5. However, the biological production of valerolactam has been limited by the inadequate efficiency of enzymes to cyclize 5-aminovaleric acid to produce valerolactam. In this study, we engineered Corynebacterium glutamicum with a valerolactam biosynthetic pathway consisting of DavAB from Pseudomonas putida to convert L-lysine to 5-aminovaleric acid and ß-alanine CoA transferase (Act) from Clostridium propionicum to produce valerolactam from 5-aminovaleric acid. Most of the L-lysine was converted into 5-aminovaleric acid, but promoter optimization and increasing the copy number of Act were insufficient to significantly improve the titer of valerolactam. To eliminate the bottleneck at Act, we designed a dynamic upregulation system (a positive feedback loop based on the valerolactam biosensor ChnR/Pb). We used laboratory evolution to engineer ChnR/Pb to have higher sensitivity and a higher dynamic output range, and the engineered ChnR-B1/Pb-E1 system was used to overexpress the rate-limiting enzymes (Act/ORF26/CaiC) that cyclize 5-aminovaleric acid into valerolactam. In glucose fed-batch culture, we obtained 12.33 g/L valerolactam from the dynamic upregulation of Act, 11.88 g/L using ORF26, and 12.15 g/L using CaiC. Our engineered biosensor (ChnR-B1/Pb-E1 system) was also sensitive to 0.01-100 mM caprolactam, which suggests that this dynamic upregulation system can be used to enhance caprolactam biosynthesis in the future.


Assuntos
Caprolactama , Corynebacterium glutamicum , Caprolactama/metabolismo , Corynebacterium glutamicum/metabolismo , Regulação para Cima , Lisina , Chumbo/metabolismo , Fermentação , Engenharia Metabólica
14.
Nature ; 615(7950): 127-133, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36813966

RESUMO

Haematopoietic stem cells (HSCs) are a rare cell type that reconstitute the entire blood and immune systems after transplantation and can be used as a curative cell therapy for a variety of haematological diseases1,2. However, the low number of HSCs in the body makes both biological analyses and clinical application difficult, and the limited extent to which human HSCs can be expanded ex vivo remains a substantial barrier to the wider and safer therapeutic use of HSC transplantation3. Although various reagents have been tested in attempts to stimulate the expansion of human HSCs, cytokines have long been thought to be essential for supporting HSCs ex vivo4. Here we report the establishment of a culture system that allows the long-term ex vivo expansion of human HSCs, achieved through the complete replacement of exogenous cytokines and albumin with chemical agonists and a caprolactam-based polymer. A phosphoinositide 3-kinase activator, in combination with a thrombopoietin-receptor agonist and the pyrimidoindole derivative UM171, were sufficient to stimulate the expansion of umbilical cord blood HSCs that are capable of serial engraftment in xenotransplantation assays. Ex vivo HSC expansion was further supported by split-clone transplantation assays and single-cell RNA-sequencing analysis. Our chemically defined expansion culture system will help to advance clinical HSC therapies.


Assuntos
Técnicas de Cultura de Células , Proliferação de Células , Citocinas , Células-Tronco Hematopoéticas , Humanos , Proliferação de Células/efeitos dos fármacos , Células Clonais/citologia , Células Clonais/efeitos dos fármacos , Células Clonais/metabolismo , Sangue Fetal/citologia , Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Células-Tronco Hematopoéticas/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Técnicas de Cultura de Células/métodos , Albuminas , Caprolactama , Polímeros , Receptores de Trombopoetina , Transplante Heterólogo , Análise da Expressão Gênica de Célula Única
15.
J Colloid Interface Sci ; 631(Pt B): 201-213, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36401928

RESUMO

In this contribution, we reported the preparation of nanocomposites of epoxy with one-dimensional (1D) poly(ε-caprolactam) (PA6) nanocrystals via crystallization-driven self-assembly. First, a novel diblock copolymer composed of poly(ethylene oxide) and poly(ε-caprolactam) subchains (PEO-b-PA6) was synthesized via the anionic ring-opening polymerization (ROP) of ε-caprolactam. It was found that the PEO-b-PA6 diblocks displayed crystallization-driven self-assembly (CDSA) behavior in the selective solvents (e.g., water); the 1D fibrous nanocrystals of PA6 were obtained via CDSA approach. Such a CDSA behavior was utilized to generate 1D fibrous PA6 nanocrystals into epoxy thermosets. In this case, the epoxy precursors were used as the solvent selective for PEO subchain of the diblock. Notably, the 1D fibrous PA6 nanocrystals were generated in the epoxy precursors via the CDSA approach. Upon curing, the nanocomposites (i.e., the nanostructured thermosets containing PA6 nanocrystals) were successfully obtained. It was found that epoxy thermoset was significantly nanoreinforced by the PA6 nanocrystals. In the meantime, the fracture toughness of the materials was significantly improved with the incorporation of 1D fibrous PA6 nanocrystals.


Assuntos
Caprolactama , Nanocompostos , Nanopartículas , Cristalização , Resinas Epóxi , Solventes
16.
Chem Soc Rev ; 51(19): 8258-8275, 2022 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-36047318

RESUMO

Ring opening polymerization (ROP) of lactams is a highly efficient and versatile method to synthesize polyamides. Within the last ten years, significant advances in polymerization methodology and monomer diversity are ushering in a new era of polyamide chemistry. We begin with a discussion of polymerization techniques including the most widely used anionic ring opening polymerization (AROP), and less prevalent cationic ROP and enzyme-catalyzed ROP. Next, we describe new monomers being explored for ROP with increased functionality and stereochemistry. We emphasize the relationships between composition, structure, and properties, and how chemists can control composition and structure to dictate a desired property or performance. Finally, we discuss biomedical applications of the synthesized polyamides, specifically as biomaterials and pharmaceuticals, with examples to include as antimicrobial agents, cell adhesion substrates, and drug delivery scaffolds.


Assuntos
Anti-Infecciosos , Nylons , Materiais Biocompatíveis , Caprolactama/análogos & derivados , Lactamas/química , Nylons/química , Preparações Farmacêuticas , Polimerização , Polímeros
17.
Int J Mol Sci ; 23(16)2022 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-36012282

RESUMO

Nylon 6/acrylonitrile-butadiene-styrene nanocomposites were prepared by mixing in a molten state and injection molded for application in electromagnetic interference shielding and antistatic packaging. Multi-wall carbon nanotubes (MWCNT) and maleic anhydride-grafted ABS compatibilizer were incorporated to improve the electrical conductivity and mechanical performance. The nanocomposites were characterized by oscillatory rheology, Izod impact strength, tensile strength, thermogravimetry, current-voltage measurements, shielding against electromagnetic interference, and scanning electron microscopy. The rheological behavior evidenced a severe increase in complex viscosity and storage modulus, which suggests an electrical percolation phenomenon. Adding 1 to 5 phr MWCNT into the nanocomposites produced electrical conductivities between 1.22 × 10-6 S/cm and 6.61 × 10-5 S/cm. The results make them suitable for antistatic purposes. The nanocomposite with 5 phr MWCNT showed the highest electromagnetic shielding efficiency, with a peak of -10.5 dB at 9 GHz and a value around -8.2 dB between 11 and 12 GHz. This was possibly due to the higher electrical conductivity of the 5 phr MWCNT composition. In addition, the developed nanocomposites, regardless of MWCNT content, showed tenacious behavior at room temperature. The results reveal the possibility for tailoring the properties of insulating materials for application in electrical and electromagnetic shielding. Additionally, the good mechanical and thermal properties further widen the application range.


Assuntos
Acrilonitrila , Nanocompostos , Nanotubos de Carbono , Butadienos , Caprolactama/análogos & derivados , Condutividade Elétrica , Polímeros , Estireno
18.
ACS Appl Bio Mater ; 5(7): 3509-3518, 2022 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-35793521

RESUMO

Medical protective materials have broadly drawn attention due to their ability to stop the spread of infectious diseases and protect the safety of medical staff. However, creating medical protective materials that combine excellent liquid shielding performance and outstanding mechanical properties with high breathability is still a challenging task. Herein, a polyester/polyamide 6 (PET/PA6) bicomponent microfilament fabric with tunable porosity for comfortable medical protective clothing was prepared via dip-coating technology and an easy and effective thermal-belt bonding process. The dip coating of the C6-based fluorocarbon polymer endowed the samples with excellent hydrophobicity (alcohol contact angles, 130-128°); meanwhile, by adjusting the temperature and pressure of the thermal-belt bonding process, the porosity of the samples was adapted in the range of 64.19-88.64%. Furthermore, benefitting tunable porosity and surface hydrophobicity, the samples also demonstrated an excellent softness score (24.3-34.5), agreeable air permeability (46.3-27.8 mm/s), and high hydrostatic pressure (1176-4130 Pa). Significantly, the created textiles successfully filter aerosol from the air and display highly tensile strength. These excellent comprehensive performances indicate that the prepared PET/PA6 bicomponent microfilament fabrics would be an attractive choice for medical protective apparel.


Assuntos
Poliésteres , Têxteis , Citoesqueleto de Actina , Caprolactama/análogos & derivados , Humanos , Polímeros , Porosidade , Tomografia por Emissão de Pósitrons , Roupa de Proteção
19.
Acta Chim Slov ; 69(2): 251-260, 2022 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-35861067

RESUMO

Soft nanoparticles are an important class of material with potential to be used as carriers of active compounds. Swollen, penetrable particles can act as a host for the active ingredients and provide stability, stimuli-responsiveness and recyclability for the guest. Thermoresponsive colloidal gel particles are especially attractive for such applications due to the extremely soft structure, size and responsiveness. Poly(N-vinylcaprolactam) (PNVCL) is a much studied, popular thermoresponsive polymer. The polymer has low toxicity and the phase transition temperature is close to body temperature. During the phase transition, the polymer becomes less soluble, the particle expels a large part of water and the particle collapses to a more compact form. The diffusion of material in and from the particles is largely affected by this transition.  As the solubility of the polymer changes, so do the interactions with the loaded compound.  This feature article focuses on the synthetic methods, properties and applications of soft PNVCL particles.


Assuntos
Caprolactama , Caprolactama/análogos & derivados , Caprolactama/química , Polímeros/química , Temperatura , Água/química
20.
Molecules ; 27(11)2022 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-35684423

RESUMO

Limited tissue selectivity and targeting of anticancer therapeutics in systemic administration can produce harmful side effects in the body. Various polymer nano-vehicles have been developed to encapsulate therapeutics and prevent premature drug release. Dually responsive polymeric vesicles (polymersomes) assembled from temperature-/pH-sensitive block copolymers are particularly interesting for the delivery of encapsulated therapeutics to targeted tumors and inflamed tissues. We have previously demonstrated that temperature-responsive poly(N-vinylcaprolactam) (PVCL)-b-poly(dimethylsiloxane) (PDMS)-b-PVCL polymersomes exhibit high loading efficiency of anticancer therapeutics in physiological conditions. However, the in-vivo toxicity of these polymersomes as biocompatible materials has not yet been explored. Nevertheless, developing an advanced therapeutic nanocarrier must provide the knowledge of possible risks from the material's toxicity to support its future clinical research in humans. Herein, we studied pH-induced degradation of PVCL10-b-PDMS65-b-PVCL10 vesicles in-situ and their dually (pH- and temperature-) responsive release of the anticancer drug, doxorubicin, using NMR, DLS, TEM, and absorbance spectroscopy. The toxic potential of the polymersomes was evaluated in-vivo by intravenous injection (40 mg kg-1 single dose) of PVCL10-PDMS65-PVCL10 vesicles to mice. The sub-acute toxicity study (14 days) included gravimetric, histological, and hematological analyses and provided evidence for good biocompatibility and non-toxicity of the biomaterial. These results show the potential of these vesicles to be used in clinical research.


Assuntos
Portadores de Fármacos , Polímeros , Animais , Materiais Biocompatíveis , Caprolactama/análogos & derivados , Dimetilpolisiloxanos , Doxorrubicina/química , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos , Camundongos , Polímeros/química
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