Cellulose最新文献

The dual-functional nanostructures show great promise for biomedical applications, exhibiting selective cytotoxicity against cancer cells while also serving as a crucial component in textile screen-printing for smart materials. In this study, we successfully synthesized polyethylene glycol-hibiscus extract copper (II) oxide nanoparticles (PEG/HS/CuO NPs) using a simple one-step sonosynthesis method that leverages ultrasonic irradiation. Comprehensive characterization of the synthesized PEG/HS/CuO NPs was performed using transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) analysis, and Fourier-transform infrared spectroscopy (FTIR). The incorporation of PEG/HS/CuO NPs into guar gum photochromic solution (GP) caused a significant color change after 6 ± 1 min of UV light exposure and resulted in visible coloration on cellulose-based textiles after screen printing, providing an alternative strategy for smart fabrics. Moreover, cytotoxicity experiments demonstrated the selective toxicity of green PEG/HS/CuO NPs against cancer cells. In this study, the human colon cancer cell line HCT116, breast cancer cell line MCF-7, and normal HUVEC cells were examined. PEG/HS/CuO NPs NPs induced apoptosis, cell cycle arrest, and down-regulation of CD44 antibody expression in MCF-7 cells, highlighting their potential as effective chemotherapy agents.

Cellulose is the most abundant renewable biomaterial, featuring a wide range of applications. In the form of aqueous suspension of microfibrils, it is also highly processable, which has opened new doors to a number of industrial applicative scenarios. In particular, extrusion 3D printing enables the free-form fabrication of stable cellulose-based constructs with applications, among others, in flexible electronics. However, most of these devices still rely on costly metal elements and show a relatively low cellulose fraction, mainly associated to the substrate. Here, we applied an optimization strategy to the microextrusion-based 3D printing of microfibrillated cellulose/hydroxypropylcellulose composites, which were further modified by the addition of nanocarbon and doped ZnS powders, thus endowing the materials with conductive and electroluminescent properties, respectively. The formulations were also demonstrated to be non-cytotoxic and, in principle, suitable for application in contact with living matter. In conclusion, we fabricated and integrated cellulose-based 3D printed materials with a broad applicative potential ranging from flexible electronics to biocompatible devices, potentially leading to the development of a new class of cellulose-based (bio)electronic components with reduced environmental impact.

Nanocellulose, which can be derived from abundant renewable plant sources, possesses outstanding properties such as nano-size, high strength, and high reactivity, rendering it a promising alternative to fossil-based materials in the future. However, the conventional drying of nanocellulose aqueous suspensions tends to result in significant aggregation, which substantially impedes the functionalization of nanocellulose by organic modifying reagents. This study presents an innovative method for drying nanocellulose from aqueous suspension into ultrafine powders while preserving its nanoscale properties. Ammonium bicarbonate was introduced into the aqueous suspension of cellulose nanofibrils (CNFs) to precipitate CNFs that were then dispersed in n-butanol. During the evaporation process, the ammonium bicarbonate decomposed, and the water evaporated, leading to the drying of CNFs in pure n-butanol into an ultrafine powder with high dispersibility. When prepared with a large amount of n-butanol, these ultrafine powders demonstrate enhanced redispersibility in water, with the ability to form a stable suspension through simple agitation. Our research in this paper centers on elucidating the dispersion mechanism of CNF ultrafine powders. We suggest that CNF ultrafine powders dried from n-butanol form a loosely porous mesoporous structure. In the absence of significant changes in crystallinity, the substantial reduction in the inaccessible area of the amorphous regions is likely responsible for their enhanced redispersibility in water. Additionally, by capitalizing on the micro- and nano-structural characteristics of CNF ultrafine powders, we have successfully developed a superhydrophobic coating by applying hydrophobic modification and adhering the treated powder to the surface of filter paper. This outcome not only substantiates the practical applicability of CNF ultrafine powders but also affirms their micro- and nano-dimensional structural attributes. This paper proposes a straightforward and viable approach for the reaction of functionalized organic reagents with nanocellulose, thereby significantly broadening its potential applications.

Cellulose nanofibril (CNF) suspension usually has a relatively low concentration, and in order to reduce its transportation and storage cost concentration process is introduced. However, in the concentration and following the redispersion process, irreversible binding between fibrils was formed, causing changes in the structural characteristics of fibrils, and accurately evaluating the properties of CNFs was highly necessary. In this study, the prepared 1.0 wt% CNF suspension was dewatered by centrifugation, obtaining concentrated CNFs labeled 1-CNF. Then, the 1-CNF sample was diluted and redispersed by a high-speed homogenizer and dewatered again, preparing re-concentrated CNFs labeled 2-CNF. The concentrated and redispersed CNFs produced pore structures among fibrils, which could be used to reflect their characteristics. The pore size distribution of CNFs was analyzed by a solute exclusion technique based on a range of molecular weight PEG and dextran molecules. The total volume of inaccessible pores in the CNFs increased with the concentration degree. The most accessible pore sizes of 1-CNF and 2-CNF were 35 Å and 53 Å, respectively. The presence of pore structure in CNFs also affected the properties of CNF films. The mechanical properties, oxygen and water vapor barrier properties, and transmittance performance of 1-CNF films were higher than that of 2-CNF films, while the 2-CNF showed higher water absorption properties.

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Micro/nano protein fibers have attracted increasing attention owing to their advantageous properties, including high tensile strength, biodegradability, and exceptional thermal stability, which make them suitable for applications in advanced materials. However, traditional preparation methods often suffer from high material costs and energy-intensive manufacturing processes, which hinder large-scale production. Herein, we present an innovative low-carbon approach for converting tannery sludge into micro/nano protein fibers, which converts 62.14% of the protein in sludge into protein fibers smaller than 5 μm and retains 97.61% of the chromium in the fibers. Surprisingly, the micro/nano protein fibers enhance the cellulose-based films for mechanical properties and flame retardancy. The incorporation of 10% protein fibers resulted in a 55.40% increase in the tensile strength of the cellulose-based films, along with significant improvements in Young's modulus (22.39%) and toughness (38.25%). Furthermore, the addition of micro/nano protein fibers substantially enhances the cellulose-based films for flame retardancy, as demonstrated by a 16 °C increase in the peak temperature of heat loss. Moreover, the peak heat release rate was reduced by 21.60%, while the total heat release decreased by 28.17%. This low-carbon and eco-friendly process utilizing leather tannery sludge not only provides a sustainable source of raw materials for protein fibers, but also contributes to the circular economy by repurposing industrial waste.

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Protein fibers were prepared from tannery sludge by alkali-oxygen cooking, and their mechanical and flame retardant properties were explored.

This study fabricated bacterial cellulose (BC) films derived from Nata de coco waste to enhance their ferroelectric properties. Doping BC with Ag and ZnO nanoparticles (NPs) resulted in conductive and semi-conductive BC films. The aggregation of AgNPs and ZnONPs on the BC films significantly improved remnant polarization (P_r) and dielectric constant (ε′) values, which ranged from 0.014 to 0.1 and 4.29 to 8.23, respectively. The polar hydrogen bonding within the non-centrosymmetric structure of BC created a net dipole moment, promoting piezoelectric behavior. When AgNPs were introduced using a 1 mM silver nitrate solution, the P_r and ε′ values increased to 0.028 and 6.59, respectively. Doping with ZnONPs via a 40 mM zinc nitrate solution further raised the P_r and ε′ values to 0.10 and 8.23, respectively, indicating an enhanced dipole moment within the BC films. Electrical poling aligned the dipoles in each film under a maximum electric field of 360 kV/cm, a critical factor for ferroelectric properties. These BC-based ferroelectric films demonstrate promising potential for future applications.

Cellulose phosphorylation as a pretreatment for CNF production is a robust process allowing to modify the surface charge of the fiber. However, cellulose phosphorylation is associated with a yellowing of the substrate and variations in the grafting of phosphate groups leading to crosslinking during intense curing. In this study, a design of experiment was conducted on a process of paper impregnation to limit the color change and maximize the degree of grafting of cellulose. The impregnation of the substrate was found to occur very rapidly, namely at 10s maximum. Whereas the color change was found to be dependent only on the curing parameters (time and temperature). The charge content model was reduced to 2 variables, i.e., the curing parameters, since the impregnation time was previously established to be very short and complete. Consequently, both models were combined allowing to determine optimal curing parameters: a temperature of 150°C for 20 min., yielding a minimum color change (6.0) and maximum charge content (1.0 mmol/g). Moreover, cellulose phosphorylation was characterized in bulk and surface by XPS and NMR, respectively. It did not reveal crystallinity changes in the pretreated cellulose. ³¹P NMR allowed the estimation of the amount of crosslinking within cellulose matrix.

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Fe(II) is a major cation that participates in biogeochemical cycles in diverse ecosystems and serves as a trace element for living organisms. Fe(II) can also become a health hazard when it is either insufficient or overabundant in water sources. Thus, the development of performant, easy-to-use, stable, and inexpensive portable systems is a central technological challenge for the on-site monitoring of free Fe(II) in different aqueous solutions. Here, we aimed to develop a sensitive and robust colorimetric Fe(II) sensor by grafting, via ester bonds, the chromogen xylenol orange (XO) on a support made of recycled waste cotton fabric (WCF). The resulting XO-grafted WCF (xWCF) sensing strip quantified free Fe(II) in tap water, lake water, seawater, and different kinds of wastewater with a limit of detection of only 0.0053 mg/L and an accuracy of at least 96%. The xWCF device, with its resistant and sustainable support, was selective for Fe(II) among 16 other metallic and non-metallic ions and was stable for long-term storage. Notably, the xWCF strip could be reused several times for free Fe (II) detection without significant variations in its performance. The high efficiency and unique characteristics of the xWCF Fe(II) sensor make it highly suitable for real-life applications.

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Cellulose is a bio-based material that has garnered increasing research interest due to its abundant reserves and excellent properties. However, its inherent flammability limits its widespread use. This study addresses this issue by combining cellulose with industrial waste fly ash (FA), not only mitigating its flammability but also transforming FA into a value-added product. Through hot pressing and freeze-drying processes, flame-retardant cellulose/FA films and foams were developed. This experimental method not only enhances the application potential of cellulose but also promotes the high-value reuse of FA, aligning with sustainable development principles. SEM images reveal good interaction between FA and cellulose. In terms of thermal performance, the maximum decomposition rates of C1-Fx and C2-Fx decreased systematically with increasing FA content. The addition of FA significantly improved flame retardancy, with the limiting oxygen index (LOI) of C1-F30 and C2-F30 reaching approximately 31% and 29%, respectively. Furthermore, the peak heat release rate of C2-Fx significantly decreased from 363.6 to 118.2 kW/m², and the total heat release dropped from 7.3 to 4.1 MJ/m². In summary, this study successfully utilized industrial waste FA to develop a bio-based flame-retardant material through a straightforward process, offering a viable solution to enhance the flame retardancy of cellulose and promote the reutilization of industrial waste.

In this report, we conducted the synthesis, fabrication, and characterization of chitosan-azobenzene films using the solvent evaporation method. The samples were characterized through thermogravimetric analysis, differential scanning calorimetry, contact angle measurements, atomic force microscopy, and ultraviolet‒visible spectroscopy. The main goal of this study was to investigate the photoactivity of chitosan-azobenzene films utilizing LED light as a radiation source. Remarkably, employing both ultraviolet and visible light allowed us to witness the photoisomerization phenomenon of azobenzene, i.e., the direct process (trans → cis), in the films. Moreover, we investigated the reverse process (cis → trans) in the absence of light. Interestingly, this step can be executed in darkness, indicating zero energy demand for this phase of the process. The results indicated that these self-supporting materials are capable of harvesting and storing light energy.