Cellulose最新文献

Wound healing represents a complex biological process often hampered by bacterial infections, in particular those caused by Staphylococcus aureus, which is already multiresistant to many antibiotics. In this sense, enzybiotics have additional advantages over conventional antibiotics, since they provide pathogen specificity and do not contribute to antibiotic resistance. However, their soluble administration at the wound site would result in enzyme leakage. On the other hand, bacterial cellulose (BC) pellicles present a very promising dressing and scaffold, given its high purity, water retention capacity, and barrier effect in the wound against possible contaminants. In this study, we present a novel approach that incorporates the enzybiotic CHAP_K into BC to develop functionalized membranes that exhibit targeted and controlled antimicrobial activity against S. aureus. The kinetic tests revealed a continuous loading of the enzybiotic into BC until it reaches a maximum and a two-stage release process, characterized by an initial fast release followed by a sustained release. Attenuated total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), and Confocal Laser Scanning Microscopy (CLSM) confirmed the incorporation and the preferential surface localization of CHAP_K within the BC membranes. Finally, the BC/CHAP_K materials demonstrated the sustained reduction of up to 4 logarithmic units in the viability of S. aureus. Overall, the biomaterials developed here exhibit promising antimicrobial efficacy against S. aureus, offering a potential strategy for wound management and skin infection control while maintaining unharmed the commensal skin microbiota, which impairment could compromise the integrity of the skin barrier function.

Developing natural cotton textiles in personal thermal management applications is of great significance for defending human against adverse climate conditions. However, the intrinsic low optical energy conservation of cotton in terms of human mid-infrared radiation and solar spectrum prevents it from realizing high-efficient thermal retention. Herein, by leveraging a facile technique involving polydopamine (PDA)-assisted ion deposition, we firmly embed silver nanoparticles onto cotton fibers, creating silver-nanoprocessed cotton fabrics (Ag-fabric) with high human mid-infrared reflectivity and superior water/wear resistance. Meanwhile, the localized surface plasmon resonance effect of the PDA and silver nanoparticles contributes to high solar spectrum absorptivity. The as-prepared Ag-fabric demonstrates nearly 2 °C higher temperature compared to unadorned cotton fabrics due to enhanced human mid-infrared radiation, and the outdoor tests show a temperature increase of average 8 °C when covering artificial skin. Moreover, the uniformly distributed silver nanoparticles on hierarchically assembled cotton fibers endow the Ag-fabric with desirable Joule heating performance (~ 40.7 °C at 1 V), self-cleaning capacity, and antibacterial properties, while maintaining breathability and comfort. These merits of the Ag-fabric present promising advantages to transfer natural cotton into commercially available thermal management wearables and eco-textiles.

In this study, a novel strategy is proposed to prepare eco-friendly flame-retardant cotton fabrics, where chloroacetic acid (MCA) and L-glutamic acid (L-Glu) are used as raw materials to enhance the chelation ability between carboxyl groups (-COO-) and calcium ions (Ca²⁺). The morphological and structural characterizations of the prepared cotton fabrics indicate that the three free hydroxy groups (2, 3, 6) in the cellulose macromolecule are chemically modified to graft a large number of carboxyl groups, and Ca²⁺ ions are successfully chelated on the surface of cotton fabric. The thermal stability of cotton fabrics is greatly improved in both air and nitrogen atmosphere. The residual mass of flame-retardant cotton fabric (COT-Glu–Ca) is much higher than that of original cotton fabric, increasing from 0.03% to 5.6% in air and from 8.1% to 28.2% in N₂, respectively. At the same time, the limiting oxygen index (LOI) of COT-Glu–Ca fabric is as high as 33.6%. The prepared flame-retardant cotton fabric can undergo vertical combustion tests with a char length of only 53 mm, and afterflame and afterglow are not observed, which proves that the grafted cotton fabric had a good flame retardancy due to a series of modifications and adsorption of Ca²⁺ ions. The properties of the cotton fabric, including tensile strength, whiteness, and moisture absorption, are all retained at a satisfactory level. Overall, this study provides a promising strategy for manufacturing eco-friendly, phosphorus-free, halogen-free, and fire-resistant cotton fabrics with enhanced metal ion chelation ability.

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This work aimed for the preparation of zinc oxide nanoparticles (ZnONPs) using hydroxyethyl cellulose (HEC) as a capping agent. The preparation of ZnONPs was first affirmed using UV–Vis spectra, illustrating the presence of an absorption peak at 364 nm. Meanwhile, the well distribution of ZnONPs was proved via transmission electron microscope (TEM). Then, ZnONPs were blended with a solution composed of HEC and sodium alginate (SA) to form an efficient hydrogel that crosslinked with calcium chloride (CaCl₂). FTIR, SEM–EDX, and swelling ratios were employed to confirm the successful preparation of ZnONPs@HEC-SA in a hydrogel form. This investigation was extended to explore the efficacy of HEC-SA hydrogel and ZnONPs@HEC-SA hydrogel in removing Crystal Violet (CV) dye from water. Various variables, such as varied pH levels, contact periods, and concentrations of ZnONPs, were used to assess the hydrogel's adsorption capabilities. ZnONPs@HEC-SA hydrogel was also tested for photocatalytic degradation efficiency when exposed to visible light. At greater ZnONPs@HEC-SA dosage and shorter irradiation periods, our findings showed that the ZnONPs@HEC-SA hydrogel completely degraded (100%) the CV dye after 105 min. The maximum adsorption capacity observed was 320 mg/g, indicating a large removal capacity of the hydrogel. Besides, the reusability of the hydrogel was confirmed by its capability to maintain influential adsorption effectiveness over five consecutive cycles. The adsorption capacity of the tested hydrogel increased exponentially as the pH of the CV dye solution decreased. The nature of ZnONPs@HEC-SA hydrogel was reaffirmed by adding SA to the mixture, as detected by a point zero charge (PZC) of 8.4. The ZnONPs@HEC-SA hydrogel displays a considerable potential for applications in wastewater treatment. Its dual functionality as a photocatalyst and adsorbent for CV dye reduction, integrated with its antimicrobial properties, makes it a versatile and effective solution for managing pollution in water sources owing to its durability and efficiency over multiple cycles, enhancing its appeal for practical use in wastewater treatment processes.

To overcome challenges such as pickling, desulphurization, and viscosity reduction experienced during the integration of microcapsules into viscose spinning solutions through the wet spinning process, this study employed the interfacial polymerization method. Polyurea (PUA) and polyurethane (PU) were used as shell materials, with sliced paraffin and wormwood essential oil (WEO) as core materials, to construct double-shell multifunctional microcapsules (DM). These microcapsules were then introduced into a viscose spinning solution. A functional regenerated cellulose fiber was prepared by incorporating sodium alginate and carboxymethyl cellulose as thickeners. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to analyze the chemical component and structure of the DM. The morphology remained intact without damage after the spinning process using viscose wet spinning. Differential scanning calorimetry (DSC), along with an antibacterial experiment and aroma test, revealed that the functional regenerated cellulose fibers exhibited an enthalpy of crystallization and melting of 24.5 J/g and 35.4 J/g, respectively, and manifested a remarkable 100% inhibition rate against Escherichia coli. The microcapsule-based regenerated fibers prepared in this study significantly advance the application of microcapsules in functional viscose wet spinning processes.

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This study investigated the significant impact of the silanization modification using Vinyltrimethoxysilane (VTMO) and the concentration of Cellulose Nanofibers (CNFs) on the sustainability and thermal insulating potential of CNF aerogels. The research comprehensively explored preparation methods, fundamental characteristics, and the thermal insulation performance of CNF aerogels. It notably identified the superior thermal conductivity of the aerogel with 0.8 wt% CNF concentration, which measured at 0.0265 W/(m·K). Utilizing a miniature wooden house prototype, the research evaluated a roofing system that integrated CNF aerogel and conventional wood, taking into account conductive, convective, and radiative heat transfers. The results revealed a remarkable reduction in energy consumption for air conditioning (up to 81.70%) and associated CO₂ emissions when the aerogel roofing was applied, as compared to the wooden counterpart under the same environmental conditions. These findings not only confirmed the exceptional thermal insulation performance of CNF aerogels but also highlighted their economic feasibility, paving the way for their expanded application in a variety of practical settings.

The growing demand for sustainable products has spurred research into renewable materials, with cellulose-based materials emerging as prominent candidates due to their exceptional properties, abundance, and wide-ranging applications. In this context, there is a need to develop a better fundamental understanding of cellulose interactions such that we can continue to design and improve sustainable materials. Individual interactions can be difficult to assess in bulk fibre-based materials and therefore cellulose model materials have become indispensable tools for researchers as they can facilitate the study of cellulose interactions at a molecular level enabling the design of sustainable materials with enhanced properties.

This study presents a new methodology for studying the effects of surface treatments on the individual fibre–fibre joint strength using wet-spun cellulose nanofiber (CNF) filaments as model materials. The Layer-by-Layer assembly technique is used to modify the surface chemistry of the model materials as well as bleached and unbleached hardwood Kraft fibres, demonstrating its potential to enhance adhesive properties and overall mechanical performance of papers made from these fibres. The study further explores the impact of increasing network density through wet-pressing during paper preparation, showcasing a comprehensive approach to molecularly tailor fibre-based materials to achieve superior mechanical properties. The proposed methodology provides a time-efficient evaluation of chemical additives in paper preparation.

There is an increasing demand for bio-based chitosan materials doped with synthetic polymers for sustainable production and economic development. Due to their helpful medical applications, chitosan-based nanocomposites containing ZnO nanoparticles (NPs) are very interesting. In the present study, new composite materials containing newly synthesized methacrylate-based polymer Poly(2-{[(2,4-chlorophenyl)methyl]amino}-2-oxoethyl-2-methylprop-2-enoate (PDCBMA), chitosan (CS) and biosynthesized ZnO NPs were produced by hydrothermal method. The composites were characterized by FTIR, XRD, SEM, EDX, and TEM. Synthetic PDCBMA blended with CS decreased the thermal stability of pure CS, but the addition of ZnO NPs slightly increased the thermal stability. Blending with PDCBMA and adding ZnO NPs increased the glass transition temperature (Tg) of pure CS. While the antibacterial activities of PDCBMA-CS/ZnO nanocomposites were significantly increased compared to CS, the antifungal effect was low. It was determined that ZnO NPs and PDCBMA included in the structure of CS were anticarcinogenic on A549 cells even at the lowest concentration (16 µg/mL). It was determined that the wound-healing effect of the PDCBMA-CS mixture was better than that of the control group, and the nanocomposite containing 3% ZnO NPs had a wound-healing activity close to the control group. The antimicrobial activity of the nanocomposite containing PDCBMA-CS blend and 3% ZnO NPs is higher than CS, so it is considered a good alternative as a substitute wound-healing material.

The study investigated the structures and properties of lyocell composite fibers with acetylated cellulose with varying relative acetylation substitution degrees (RDS). During pretreatment with NaOH/ethanol solution, some acetyl groups in the acetylated cellulose were hydrolyzed, leading to improve solubility in N-methylmorpholine-N-oxide (NMMO). The RDS was utilized to quantify the content of acetyl groups and acetylated cellulose with RDS between 0.516 ~ 0.571 that could dissolve in NMMO completely. The compatibility between cellulose and acetylated cellulose, with RDS values of 0.516, 0.543 and 0.571 respectively, was demonstrated through rheological and contact angle tests. Although the addition of acetylated cellulose did not change the crystalline structure and comprehensive performance of the composite fiber, it mainly disturbed molecular orientation of amorphous region, crystallinity and grain size. Besides the strengthening of hydrogen bonding between the two components, and the transverse connection between the aggregates were enhanced, thus reducing fibrillation. This paper provides a green modification approach that can be scaled up for industrial application, aiming to mitigated fibrillation issues in lyocell fibers.

Hydrogel smart windows with light modulation capability have received widespread attention because they can meet the requirements of indoor lighting at daytime, privacy protection at night and energy saving. However, it remains challenging to achieve these multiple goals simultaneously and enable active actuation to meet the temporary needs of users. In this study, a thermal and solvent responsive hydrogel smart window was developed by introducing hydroxypropyl cellulose (HPC) and sodium dodecyl sulfate (SDS) micelles into a polyacrylamide (PAAm) cross-linked network. By adding different concentrations of NaCl solution, the hydrogels underwent upper critical solution temperature (UCST)- and lower critical solution temperature (LCST)-type phase transitions in the ranges of 1 − 15 °C and 25 − 80 °C, respectively, which enabled the hydrogel to achieve a reversible transition between opacity and transparency with temperature change. The smart window exhibited an excellent solar modulation ability (T_lum = 91.39%, ΔT_sol,_15−5℃ = 68.67%, ΔT_sol,_15−40℃ = 62.50%) and effective IR shielding. Furthermore, actively actuated light modulation of hydrogel smart windows was achieved by spraying ethanol on the hydrogel surface. Ethanol stimulation and volatilization induced the reconfiguration and dissociation of hydrogen bonds between HPC and PAAm molecular chains, resulting in reversible transparency transitions. We anticipate that this facile strategy for preparing thermal and solvent responsive hydrogels could serve as a promising alternative for designing phase change hydrogels for a variety of applications.

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