Macromolecular Research最新文献

Developing a novel approach for the administration of catechin that ensures sustained bioactivity, even at low doses, is crucial. In this regard, hydrogels were synthesized by polyion complexation of carboxymethyl cellulose (CMC) and chitosan (CS) grafted with epigallocatechin gallate (EGCG-g-CS), which can maintain enduring antioxidant activity. We initially synthesized grafted chitosan with various grafting ratios using a free-radical grafting method. Polyionic complexes were formed by ionic bonding of the amino groups in EGCG-g-CS with the carboxyl groups in CMC. After lyophilization, a hydrogel with a porous structure was obtained. Scanning electron microscopy (SEM), thermogravimetric differential thermal analysis (TG–DTA), and Fourier transform infrared (FT-IR) analyses of the gel structures were conducted. The swelling properties and porosity of the hydrogels were affected by the grafting ratio. The hydrogel gradually released EGCG under low pH conditions owing to chitosan solubilization, resulting in hydrogel disintegration. Additionally, the hydrogels demonstrated cell adhesion and viability. This study suggests that bio-based materials have potential as pH-dependent catechin-releasing materials.

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Preparation of hydrogel using catechin-grafted chitosan and carboxymethyl cellulose

The purpose of this study was to characterize the biological activity of konjac glucomannan (KGM) according to its molecular weight change. KGM-degrading bacterial strain, N3 was isolated from soil and named Bacillus aerophilus following 16S rDNA sequencing and homology analysis. KGMase, a thermophilic konjac glucomannan-degrading enzyme, was partially purified by treating the culture supernatant of strain B. aerophilus N3 with 50% ammonium sulfate followed by rigorous heating at 75 °C for 30 min. The molecular weight (MW) of KGMase was determined to be approximately 41,000 by silver staining following sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE). The biochemical properties stipulated that KGMase is optimally active at 45 °C and pH 6.5 which shows the high temperature and pH stability of KGMase. Manno-oligosaccharides (MOs) derived from the hydrolysis of KGM by KGMase showed a concentration-dependent increase in tyrosinase activity. MOs are bioactive compounds derived from the hydrolysis of KGM by the thermophilic KGMase of B. aerophilus and the outcomes of our study demonstrated that MOs will be suitable for application in the cosmetics industry.

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The polymer was engineered and synthesized for the fabrication of perovskite solar cells (PSCs). Pyrazine-based polymer is used as a hole transport material (HTM) in PSCs. Pyrazine is suitable for major transport, such as affording high hole mobility and intermolecular enhancement, and has the advantage of being inexpensive. Remarkable results are achieved by polymerizing a pyrazine-based material (PzTBr) composed of thiophene moiety with a short alkyl group on both sides and a BDT-based material (BDTEH) to yield BDTEH–PzTBr. Dopant-free processed PSCs fabricated with BDTEH–PzTBr exhibited a PCE of 13.2% for green solvent and 15.9% for chloroform solvent. Therefore, the pyrazine-based polymer is an appropriate strategy to synthesize and explore as an HTM in PSCs.

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A donor–acceptor (D–A)-conjugated polymer BDTEH–PzTBr was designed and successfully used as a hole transport material in perovskite solar cells. Due to the advantage of the molecular structure, and uniform morphology, the BDTEH–PzTBr-based device achieved a good power conversion efficiency of over 15.9%. High performance is achieved using easy synthesis processes and inexpensive materials.

In this study, the impact of two compatibilizers, ethylene terpolymer (C1) and maleic anhydride grafted polyethylene (C2), on the mechanical, thermal, and tribological properties of 30% glass-fiber-reinforced polyketone (PK) and polyketone/polyamide 6 (PK/PA-6) blend composites was investigated. In the case of 30% glass-fiber-reinforced PK composites, the mechanical test results showed that C2 significantly improves the impact resistance (over 48.8%) and elongation at break (over 13.3%) values due to the enhanced compatibility between glass fibers and the PK matrix, attributed to the maleic anhydride functionality. The tensile and flexural properties of the 30% glass-fiber-reinforced PK/PA-6 blend composites were determined to be between the values of pure PK/GF30 and PA-6/GF30 composites, which were its constituent components. Notably, these blend composites displayed higher impact resistance (19.6 kJ/m²) and elongation at break (4.86%) values than the pure PK/GF30 and PA-6/GF30 composites. The SEM images suggested that C2 creates a better interface between glass fibers and the matrix, resulting in a more cohesive structure. Differential scanning calorimeter analysis revealed two distinct glass transition temperatures, indicating the existence of two phases, and reflecting the immiscibility of the two polymers. Tribological studies showed that the friction coefficients and specific wear rates of PK/PA-6/GF30 composites were improved by increasing PK segment. The PK-25/PA6-50/GF30-C2 sample exhibited a friction coefficient of 0.341 μ and a specific wear rate of 1.15 10^¯6 mm³/Nm. Overall, the C2 proved to be a more suitable compatibilizer than C1, offering valuable insights for tailoring high-performance materials with enhanced properties.

Graphical Abstract

The influence of two compatibilizers, ethylene terpolymer (C1) and maleic anhydride grafted polyethylene (C2), on the mechanical, thermal, and tribological properties of 30% glass-fiber-reinforced polyketone and polyketone/polyamide 6 blend composites was investigated. Based on, mechanical, microscopic, thermal, and tribological results, the C2 was found to be a more suitable compatibilizer than C1 for improving the interface between glass fibers and the matrix

The luminescent properties of conjugated copolymers could be harmed due to thermo-oxidative degradation, limiting their applications. To overcome these problems, incorporating flexible and stable polymers, such as elastomers, is a simple and advantageous approach to obtaining luminescent, flexible, and thermo-resistant films. Thin films based on blends of a luminescent thiophene/fluorene copolymer (PTPF) and two elastomers, nitrile rubber (NBR) and natural rubber (NR) were prepared by a straightforward method, and thermal degradation tests were carried out at different temperatures. Oxidized structures in the PTPF chains can be observed using FTIR, and up to 330 °C for NR and to 395 °C for NBR, no significant changes were observable, however, over these temperatures, the blends also lost their luminescent properties. The characterization of the films at increasing degradation stages points to possible mechanisms associated with the degradation processes suggesting a strategy to guarantee incremented thermal protection to the conjugated material, maintaining its structural and optical properties at higher temperatures than ambient temperature, making these flexible-luminescent films interesting for applications in which the thermal resistance is a key factor to consider.

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Thermal degradation study and obtention of thermo-resistant luminescent films based on blends of thiophene/fluorene copolymer and nitrile or natural rubber

To prepare a high-stability flexible sensor for body motion monitoring, a conductive warp-knitted fabric (CWKF) with a two-bar tricot structure coated with polyaniline(PANI) was prepared by in situ polymerization, and then a waterborne polyurethane-coated conductive warp-knitted fabric (WPU/CWKF) was prepared using a simple dip-and-dry method. The structure and properties of both CWKF and WPU/CWKF were analyzed, their strain-resistance sensing properties were investigated, and their application in body motion monitoring was discussed. The results indicate that conductive treatment of in situ polymerization can give the polyester warp-knitted fabric good electrical conductivity, with a resistivity of approximately 5 Ω cm. After coating with WPU, the resistivity of the WPU/CKWF increased to approximately 40 Ω cm. Both CKWF and WPU/CKWF showed good strain-resistance sensing performance, but CWKF was more sensitive than WPU/CKWF, whereas WPU/CKWF was more stable than CWKF. Both the CWKF and WPU/CKWF sensors could monitor body motion in real time. Similar to their base materials, the CWKF sensor demonstrated a higher sensitivity for human movement monitoring, whereas the WPU/CKWF sensor exhibited higher stability.

Graphic abstract

Conductive warp-knitted fabric (CWKF) with a two-bar tricot warp-knitted structure coated with polyaniline (PANI) was prepared by in situ polymerisation. After repeated reciprocal stretching, the structure of the PANI conductive layer on the CWKF surface broke down and its conductivity changed, especially under large strains. CWKF sensors enable real-time human motion monitoring with high sensitivity

It is important to reduce environmental problems caused by biowaste materials. The large amount of biowaste generated causes serious problems on a global scale. The majority of waste produced is recycled, disposed of, or left untreated in landfills. Methane gas produced by organic waste in landfills contributes to the greenhouse impact and creates issues with leachate and odor. Furthermore, as these organic wastes decompose in landfills, toxic substances that produce unpleasant aromas and contaminate soil and aquatic habitats are discharged. The shortcomings of the traditional approach have put pressure on the waste management, farming, and industrial sectors to develop environmentally friendly ways to handle these biodegradable wastes with less pollution. According to the latest survey, the most generated biowaste was rice hull. Rice hull powder (RHP) needs some modifications for extensive applications as filler materials. By using a one-step hydrothermal process, the silver nanoparticles (AgNPs) were generated and mixed with rice hull powder. The modified rice hull powder (MRHP) was characterized by FTIR, XRD, FESEM, EDX, and thermal analysis. Through the FESEM image, the presence of small spherical-shaped particles clarifies the presence of in-situ generated AgNPs. FTIR study reveals that there is no chemical interaction between silver nanoparticles and RHP observed while generation of MRHP. The Xrd image signifies the presence of a broad hump along with a few sharp peaks clarifies that the semi-crystalline nature of MRHP. The MRHP records a slight increase in maximum inflection temperature at 365 °C due to the addition of thermally stable silver nanoparticles with 28.5 percent of the remaining residual mass. The addition of silver nanoparticles makes the MRHP has significantly improved the diameter of the zone of inhibition by 27.6 mm to 30.7 mm. This impressive change in properties suggests that the MRHP can be utilized as filler along with polymer matrices for high thermal applications.

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In situ generation of silver nanoparticles on rice hull powder

Nanocomposite chitosan-based hydrogels (chitosan-co-polycrotonic acid), with and without TiO₂, were prepared via chemical cross-linking of chitosan using sodium trimetaphosphate (STMP), followed by free radical polymerization. The structural and morphological properties of the synthesized composites were investigated and analyzed using X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and diffuse reflectance spectroscopy (DRS) techniques, as well as by determining the swelling rate and the pH at the point of zero charge (pH_pzc). The results of these analyses showed that the cross-linking of chitosan by STMP and the distribution of TiO₂ nanoparticles on the surface of the gel were both successfully achieved. In addition, the incorporation of TiO₂ particles into the hydrogel led to an increase in the swelling rate but a reduction in the band gap of titanium dioxide. These findings allowed concluding that the prepared material can be used for the efficient photocatalytic degradation of pollutants.

Graphical Abstract

The nanocomposite chitosan-based hydrogels prepared via chemical cross-linking of chitosan using sodium trimetaphosphate (STMP) with and without TiO₂ can be used for the efficient photocatalytic degradation of pollutants

To enhance the bioavailability of carborane as a potential pharmacophore for BNCT, we labeled the modified o-carborane with the near-infrared dye IR775 and encapsulated it using two types of Eudragit^® (pH-sensitive and osmotic). Consequently, four separate fluorescent complexes containing carborane were acquired. To confirm the nido-carborane presence within these complexes, the distinct peak at 2510 cm⁻¹ was detected using infrared spectroscopy as a first step. The photophysical properties were observed in phosphate buffer with different pH. The UV and fluorescence spectra of the four fluorescent complexes were very similar, with the maximum absorption wavelengths centered in the range of 773–789 nm and the emission wavelengths centered in the range of 796–811 nm. Subsequently, a stable and releasing complex L100-C-IR775 was screened through zeta potential testing and simulated release experiments in the gastrointestinal environment, and spherical shape was observed by transmission electron microscopy. AFM imaging showed a relatively smooth surface with a uniform distribution of protrusions. The L100-C-IR775 was then applied to tumor cell imaging, and it was observed that it could enter into three kinds of tumor cells, A549, HCT116 and HeLa, and distribute around the nucleus. Finally, it was shown by a cell proliferation toxicity assay (CCK8) that the compound inhibited HeLa and PC-3 cells by 50 and 51% at concentrations up to 10 µg/mL. In conclusion, the carborane fluorescent complexes prepared in this paper have good biocompatibility and demonstrate toxicity toward tumor cell proliferation. Furthermore, they have the potential to serve as a carbon borane anti-tumor prodrug.

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An acrylic encapsulated ionic polymer IR775@nido-carborane simulates release in the gastrointestinal environment, tumor cells imaging, and schematics of therapeutic mechanisms.