Simple conversion of 3D electrospun nanofibrous cellulose acetate into a mechanically robust nanocomposite cellulose/calcium scaffold

Fabrication of 3D Polycaprolactone Macrostructures by 3D Electrospinning

Building 3D electrospun macrostructures and monitoring the biological activities inside them are challenging. In this study, 3D fibrous polycaprolactone (PCL) macrostructures were successfully fabricated using in-house 3D electrospinning. The main factors supporting the 3D self-assembled nanofiber fabrication are the H3PO4 additives, flow rate, and initial distance. The effects of solution concentration, solvent, H3PO4 concentration, flow rate, initial distance, voltage, and nozzle speed on the 3D macrostructures were examined. The optimal conditions of 4 mL/h flow rate, 4 cm initial nozzle-collector distance, 14 kV voltage, and 1 mm/s nozzle speed provided a rapid buildup of cylinder macrostructures with 6 cm of diameter, reaching a final height of 16.18 ± 2.58 mm and a wall thickness of 3.98 ± 1.01 mm on one perimeter with uniform diameter across different sections (1.40 ± 1.10 μm average). Oxygen plasma treatment with 30-50 W for 5 min significantly improved the hydrophilicity of the PCL macrostructures, proving a suitable scaffold for in vitro cell cultures. Additionally, 3D images obtained by synchrotron radiation X-ray tomographic microscopy (SRXTM) presented cell penetration and cell growth within the scaffolds. This breakthrough in 3D electrospinning surpasses current scaffold fabrication limitations, opening new possibilities in various fields.

Durably dual superlyophobic cationic guar gum‑calcium complex decorated cellulose fabrics for on-demand oil/water separation

The removal to oils from water has become a global issue because of the growing of wastewater discharge and unceasing appearance of oil leaks. Herein, a kind of durably dual superlyophobic (superhydrophobic under oil and superoleophobic under water) cotton fabric (CF) was fabricated via simple assembly route that introduced guar hydroxypropyltrimonium chloride‑calcium (GHTC-Ca) chelate compound on the fabric surface. The coated CF exhibits good resistance to mechanical abrasion, corrosive aqueous solution, high temperature, and organic solvent immersion. Furthermore, due to prewetting-caused superoleophobicity underwater and superhydrophobicity underoil, the as-prepared CF can selectively separate both heavy oils and light oils in water under extremely harsh conditions with separation efficiencies as high as 98.7 % and 98.4 %, respectively. More importantly, the as-prepared fabrics are able to remove dispersed oil droplets from oil-in-water emulsions and water droplets from water-in-oil emulsions with separation efficiency of over 89 % and 91.4 %, respectively. Hence, this prominent separation performance suggests a good application prospect of GHTC-Ca functionalized CF in oily water purification.

Mimicking natural electrical environment with cellulose acetate scaffolds enhances collagen formation of osteoblasts

The medical field is continuously seeking new solutions and materials, where cellulose materials due to their high biocompatibility have great potential. Here we investigate the applicability of cellulose acetate (CA) electrospun fibers for bone tissue regeneration. For the first time we show the piezoelectric properties of electrospun CA fibers via high voltage switching spectroscopy piezoresponse force microscopy (HVSS-PFM) tests, which are followed by surface potential studies using Kelvin probe force microscopy (KPFM) and zeta potential measurements. Piezoelectric coefficient for CA fibers of 6.68 ± 1.70 pmV^-1 along with high surface (718 mV) and zeta (-12.2 mV) potentials allowed us to mimic natural electrical environment favoring bone cell attachment and growth. Importantly, the synergy between increased surface potential and highly developed structure of the fibrous scaffold led to the formation of a vast 3D network of collagen produced by osteoblasts only after 7 days of in vitro culture. We clearly show the advantages of CA scaffolds as a bone replacement material, when long-lasting structural support is needed.

Double-template-regulated biomimetic construction and tribological properties of superdispersed calcium borate@polydopamine/cellulose acetate-laurate nanocomposite

Herein, a novel superdispersed calcium borate@polydopamine/cellulose acetate-laurate nanocomposite (CTAB-CB@PDA/CAL) is successfully synthesized by a double-template-regulated biomimetic mineralization strategy using PDA/CAL as a hard template and cetyltrimethylammonium bromide (CTAB) as a soft template and surface hydrophobic modifier. The results show that CB can grow uniformly on the CAL surface, and CTAB can improve the hydrophobicity of CTAB-CB@PDA/CAL due to the synergistic effect of the double templates, which contributes to the enhanced dispersibility and long-term dispersion stability of CTAB-CB@PDA/CAL in poly-alpha-olefin (PAO) base oil. Furthermore, CB can rapidly enter the friction interface due to the long substituents of CTAB and CAL, so CTAB-CB@PDA/CAL used as a lubricant additive in PAO base oil exhibits superior tribological performance compared to CB, CB/CAL, and CB@PDA/CAL.

Crown ether-functionalized cellulose acetate membranes with potential applications in osseointegration

Due to its inherent properties and wide availability, cellulose acetate is an extremely competitive candidate for the production of polymeric membranes. However, for best results in particular applications, membrane modification is required in order to minimize unwanted interactions and introduce novel characteristics to the pristine polymer. In this study, the surface of commercial cellulose acetate membranes was functionalized with 4'-aminobenzo-15-crown-5 ether, using a covalent bonding approach. The main goal was the improvement of the membranes biomineralization ability, thus making them prospective materials for bone regeneration applications. The proposed reaction mechanism was confirmed by XPS and NMR analysis while the presence of the functionalization agents in the membranes structure was showed by ATR FT-IR and Raman spectra. The effects of the functionalization process on the morphology, thermal and mechanical properties of the membranes were studied by SEM, TGA and tensile tests. The obtained results revealed that the cellulose acetate membranes were successfully functionalized with crown ether and provided a good understanding of the interactions that took place between the polymer and the functionalization agents. Moreover, promising results were obtained during the Taguchi biomineralization studies. SEM images, EDX mapping and XRD spectra indicating that the CA-AB15C5 membranes have a superior Ca²⁺ ions retention ability, this causing an accentuated calcium phosphate deposition on the modified polymeric fibers, compared to the neat CA membrane.

Cellulose-Based Fluorescent Material for Extreme pH Sensing and Smart Printing Applications

Environment-responsive fluorescence materials are being widely investigated for instrument-free determination of various environmental factors. However, developing an eco-friendly cellulose-based fluorescent pH sensor for sensing extreme acidity and alkalinity is still challenging. Herein, a highly fluorescent and multifunctional material is developed from biopolymer-based cellulose acetate. A biopolymer-based structure containing responsive functional groups such as -C═O and -NH is constructed by chemically bonding 5-amino-2,3-dihydrophthalazine-1,4-dione (luminol) onto cellulose acetate using 4,4'-diphenylmethane diisocyanate (MDI) as a cross-linking agent. The prepared material (Lum-MDI-CA) is characterized by UV-vis, Fourier transform infrared, ¹H NMR, ¹³C NMR spectroscopies, and fluorescence techniques. The material exhibits excellent aqua blue fluorescence and demonstrates extreme pH sensing applications. Interesting results are further revealed after adding a pH-unresponsive dye such as MTPP as the reference to develop the ratiometric method. The ratiometric system clearly differentiates the extreme acidic pH 1 from pH 2 and extreme alkaline pH 12, 13, and 14 by visual and fluorescence color change response under a narrow pH range. In addition, the material is fabricated into transparent flexible fluorescent films which demonstrate an outstanding UV shielding, security printing, and haze properties for smart food packaging and printing applications.

Electrospun Nanomaterials Based on Cellulose and Its Derivatives for Cell Cultures: Recent Developments and Challenges

The development of electrospun nanofibers based on cellulose and its derivatives is an inalienable task of modern materials science branches related to biomedical engineering. The considerable compatibility with multiple cell lines and capability to form unaligned nanofibrous frameworks help reproduce the properties of natural extracellular matrix and ensure scaffold applications as cell carriers promoting substantial cell adhesion, growth, and proliferation. In this paper, we are focusing on the structural features of cellulose itself and electrospun cellulosic fibers, including fiber diameter, spacing, and alignment responsible for facilitated cell capture. The study emphasizes the role of the most frequently discussed cellulose derivatives (cellulose acetate, carboxymethylcellulose, hydroxypropyl cellulose, etc.) and composites in scaffolding and cell culturing. The key issues of the electrospinning technique in scaffold design and insufficient micromechanics assessment are discussed. Based on recent studies aiming at the fabrication of artificial 2D and 3D nanofiber matrices, the current research provides the applicability assessment of the scaffolds toward osteoblasts (hFOB line), fibroblastic (NIH/3T3, HDF, HFF-1, L929 lines), endothelial (HUVEC line), and several other cell types. Furthermore, a critical aspect of cell adhesion through the adsorption of proteins on the surfaces is touched upon.

Design of Volumetric Nanolayers via Rapid Proteolysis of Silk Fibroin for Tissue Engineering

Various methods have been studied to make a regenerated silk fibroin solution. However, most of them take too much time and effort to liquefy. Here, we report that a regenerated silk fibroin solution could be prepared within seconds through acid proteolysis for the first time. The solubilized fibroin could be applied to advanced tissue engineering. Our method shortened the production time to one day (more than 10 times) compared to the general fibroin solution preparation method. It was confirmed that the initial protein affinity nearly doubled from 0.028 to 0.076 μg·mm^-2 in FF(ac) compared to FF(aq). A fibroin nanofiber layer having a volumetric hierarchical structure was prepared by electrospinning an acid-proteolyzed fibroin solution, followed by gas foaming. In vitro results of cell adhesion and proliferation capacity of the gas-foamed scaffold were not significantly different compared to the two-dimensional (2D) fibroin nanofiber membrane, overcoming the limitations of volumetric nanofiber scaffolds. We are confident that our research will greatly contribute to the development of regenerative engineering using other proteins.

Cellulose-Acetate Coating by Integrating Ester Group with Zinc Salt for Dendrite-Free Zn Metal Anodes

Zinc (Zn) metal is considered a potential anode owing to its high theoretical capacity, safety, and low cost. However, the dendrites and corresponding side reactions in aqueous electrolytes hinder their further development in environmentally-friendly energy storage. Herein, ion-affiliative cellulose acetate (CA) coating with Zn(CF₃ SO₃ )₂ is constructed on Zn anode (CAZ@Zn). Owing to the complexation effect between the polar ester group (CO) and Zn salt (Zn²⁺ ), the CAZ polymer coating enhances the hydrophilicity of the Zn anode and reduces the interfacial resistance, allowing the rapid Zn²⁺ diffusion and homogenizing the Zn deposition in an aqueous electrolyte to suppress zinc dendrite formation and growth. Therefore, the symmetric CAZ@Zn//CAZ@Zn battery achieves reversible plating/stripping over 2800 h at 1 mA cm^-2 with 1 mAh cm^-2 , about sevenfold higher than bare Zn. The full cell fabricated with an optimized Zn anode and the NH₄ V₄ O₁₀ cathode achieves substantially stable performance, superior to that of bare Zn. This work provides a straightforward, effective, and scalable method to suppress the zinc dendrites and corresponding side reactions for aqueous Zn-ions batteries.

Solution plasma synthesis of bacterial cellulose acetate derived from nata de coco waste incorporated with polyether block amide

Cellulose acetate (CA), one of the most important cellulose derivatives, is used in various applications especially in membranes, films, fibers, filters, and polymers. Because of the tough and flexible character and resistance to acids of CA, bacterial cellulose acetate (BCA) has been used as reinforcement for high performance separator purposes. In this study, BCA was synthesized through the heterogeneous acetylation in acetic solution with H₂SO₄ as catalyst by solution plasma process (SPP) of bacterial cellulose (BC) extracted form nata de coco waste. The SPP was considered as mild, simple, and fast method for many kinds of synthesis. The solution plasma time was studied to obtain considerably high DS values (in this work, DS = 1.95). The high DS values are an important feature when considering an environmental factor, good liquid transport and excellent absorption. Furthermore, the BCA incorporated with poly ether block amide by electrospinning method is successfully fabricated as nanofibrous membranes. The proposed PEBAX/BCA nanofibrous membranes display superior sufficient porosity (74.7%), exceptional liquid electrolyte uptake (364.6%), sufficient thermal dimensional stability at 150 °C, great electrochemical stability (discharge capacity at 0.2C = 102.14 mAh g^-1), and high ionic conductivity (9.12 × 10^-3 S/cm). Furthermore, the PEBAX/BCA nanofibrous membranes can be used as high-performance separators enhancing its safety for Li-ion battery applications.

Facile fabrication of composite cellulose fibrous materials for efficient and consecutive dyeing wastewater treatment

Fabricating dye adsorbents with efficient adsorption properties is of great significance in the treatment of printing and dyeing wastewater. Herein, composite materials of polydopamine decorated cellulose fibrous nonwovens (PDA@CF NWs) were fabricated by constructing a PDA functional layer on the surface of cellulose fibers via in situ polymerization. In addition, a three-dimensional adsorbent of 3D PDA@CF NWs with good hydrophilicity, structural stability, and compression resistance could be obtained using a facilely laminating and traditional loop bonding reinforcing technique. Attributed to the efficient and uniform loading of an active PDA functional layer, the resulting PDA@CF NWs exhibited a relatively large adsorption capacity of around 91 mg g⁻¹ towards the template dye of methylene blue within a fast equilibrium time of 2 h, which was superior to most of the fibrous adsorbents. In addition, the treatment column of 3D PDA@CF NWs exhibited a breakthrough capacity of 40.9 mg g⁻¹, reaching nearly 50% of the static saturated dye-binding capacity. More importantly, the 3D PDA@CF NWs column could effectively and continuously separate the mixture of different dyes under gravity, highlighting an excellent practical performance. Thus, the PDA@CF NWs are expected to provide a promising candidate for environment-friendly, large-scale and efficient treatment of industrial printing and dyeing wastewater.

Composite materials of polydopamine decorated cellulose fibrous nonwovens were fabricated for efficient and consecutive dyeing wastewater treatment.

A multifunctional, one-step gas foaming strategy for antimicrobial silver nanoparticle-decorated 3D cellulose nanofiber scaffolds

Creating nanoparticle-decorated nanofibers in a single step can greatly speed up and scale up the production of scaffolds for various applications. In this study, we report a facile multifunctional method for the simultaneous foaming and synthesis of silver nanoparticles-covered three-dimensional cellulose using sodium borohydride (NaBH4). The physicochemical properties of the 3D cellulose-Ag scaffold were evaluated and compared to 2D CA membranes, including morphology (porous 3D vs flat 2D), mechanical properties (22.72 vs <13 MPa Young's modulus), antibacterial effect (27 vs 0 mm zone of inhibition), and biocompatibility. The findings suggest that our method enables the scaffold to be easily manufactured-indicating it can be used to scale-up manufacturing processes-with high bioactivity, antibacterial effect, and biocompatibility, showing potential as a 3D structure production method for tissue engineering and other relevant applications.