Cellulose-Based Nanofibers Processing Techniques and Methods Based on Bottom-Up Approach—A Review

In the past decades, cellulose (one of the most important natural polymers), in the form of nanofibers, has received special attention. The nanofibrous morphology may provide exceptional properties to materials due to the high aspect ratio and dimensions in the nanometer range of the nanofibers. The first feature may lead to important consequences in mechanical behavior if there exists a particular orientation of fibers. On the other hand, nano-sizes provide a high surface-to-volume ratio, which can have important consequences on many properties, such as the wettability. There are two basic approaches for cellulose nanofibers preparation. The top-down approach implies the isolation/extraction of cellulose nanofibrils (CNFs) and nanocrystals (CNCs) from a variety of natural resources, whereby dimensions of isolates are limited by the source of cellulose and extraction procedures. The bottom-up approach can be considered in this context as the production of nanofibers using various spinning techniques, resulting in nonwoven mats or filaments. During the spinning, depending on the method and processing conditions, good control of the resulting nanofibers dimensions and, consequently, the properties of the produced materials, is possible. Pulp, cotton, and already isolated CNFs/CNCs may be used as precursors for spinning, alongside cellulose derivatives, namely esters and ethers. This review focuses on various spinning techniques to produce submicrometric fibers comprised of cellulose and cellulose derivatives. The spinning of cellulose requires the preparation of spinning solutions; therefore, an overview of various solvents is presented showing their influence on spinnability and resulting properties of nanofibers. In addition, it is shown how bottom-up spinning techniques can be used for recycling cellulose waste into new materials with added value. The application of produced cellulose fibers in various fields is also highlighted, ranging from drug delivery systems, high-strength nonwovens and filaments, filtration membranes, to biomedical scaffolds.

Design of experiments for the methylene blue adsorption study onto biocomposite material based on Algerian earth chestnut and cellulose derivatives

Novel bio-composite films based on Algerian earth chestnut i.e. Bunium incrassatum roots (Talghouda, TG) and cellulose derivatives (ethylcellulose; EC and cellulose acetate; AC) are prepared and tested for methylene blue (MB) adsorption from aqueous solutions. The biomaterial films are elaborated by dissolution solvent evaporation technique and are characterized by infrared spectroscopy, X-ray diffraction, SEM and optical microscopy. The pHpzc is also determined. For the adsorption tests, design of experiments based on 23 factorial design is built and followed. So, the effects of TG:EC:AC ratio, pH and MB initial concentration are discussed on the basis of mathematical modelling using Minitab software. Mathematical relations between equilibrium adsorption percentages and capacities versus selected variables were obtained and illustrated by surface plots. The interactive effects between variables have been also identified. The results showed that the MB adsorption percentage exceeded 83% and is mostly affected by pH value. Nevertheless the adsorption capacity is affected by MB initial concentration.

Polysaccharide 3D Printing for Drug Delivery Applications

3D printing, or additive manufacturing, has gained considerable interest due to its versatility regarding design as well as in the large choice of materials. It is a powerful tool in the field of personalized pharmaceutical treatment, particularly crucial for pediatric and geriatric patients. Polysaccharides are abundant and inexpensive natural polymers, that are already widely used in the food industry and as excipients in pharmaceutical and cosmetic formulations. Due to their intrinsic properties, such as biocompatibility, biodegradability, non-immunogenicity, etc., polysaccharides are largely investigated as matrices for drug delivery. Although an increasing number of interesting reviews on additive manufacturing and drug delivery are being published, there is a gap concerning the printing of polysaccharides. In this article, we will review recent advances in the 3D printing of polysaccharides focused on drug delivery applications. Among the large family of polysaccharides, the present review will particularly focus on cellulose and cellulose derivatives, chitosan and sodium alginate, printed by fused deposition modeling and extrusion-based printing.

Porous Cellulose-Collagen Scaffolds For Soft Tissue Regeneration: Influence of Cellulose Derivatives On Mechanical Properties And Compatibility With Adipose-Derived Stem Cells.

This study deals with cellulose derivatives in relation to the collagen fibrils in composite collagen-cellulose scaffolds for soft tissue engineering. Two types of cellulose, i.e., oxidized cellulose (OC) and carboxymethyl cellulose (CMC), were blended with collagen (Col) to enhance its elasticity, stability and sorptive biological properties, e.g. hemostatic and antibacterial features. The addition of OC supported the resistivity of the Col fibrils in a dry environment, while in a moist environment OC caused a radical drop. The addition of CMC reduced the mechanical strength of the Col fibrils in both environments. The elongation of the Col fibrils was increased by both types of cellulose derivatives in both environments, which is closely related to tissue like behaviour. In these various mechanical environments, the ability of human adipose-derived stem cells (hADSCs) to adhere and proliferate was significantly greater in the Col and Col/OC scaffolds than in the Col/CMC scaffold. This is explained by deficient mechanical support and loss of stiffness due to the high swelling capacity of CMC. Although Col/OC and Col/CMC acted differently in terms of mechanical properties, both materials were observed to be cytocompatible, with varying degrees of further support for cell adhesion and proliferation. While Col/OC can serve as a scaffolding material for vascular tissue engineering and for skin tissue engineering, Col/CMC seems to be more suitable for moist wound healing, e.g. as a mucoadhesive gel for exudate removal, since there was almost no cell adhesion.

Does the Addition of Cellulosic Micro/nanofibrils Improve the Properties of Hydroxypropyl Methylcellulose Films?

Damages to ecosystems, due to the consumption of petroleum-based materials, can be mitigated with the use of biopolymers such as cellulose derivatives. The objective was to evaluate the influence of different proportions of cellulose micro/nanofibrils (MFC/NFC) on the properties of hydroxypropyl methyl cellulose (HPMC) films. Films were prepared using proportions of 0, 25, 50, 75 and 100% (w/w) of MFC/NFC of Pinus sp. in relation to HPMC. The physical, barrier, surface, optical, morphological and mechanical properties were evaluated. Data were analyzed with descriptive statistics, linear regression, principal component analysis and Pearson correlation. Solids content, basis weight and density values increased with higher MFC/NFC amount, while thickness and porosity were reduced. SEM images showed that films with more than 50% MFC/NFC had a more granular surface resulting in reduction of transparency from 80 to 65%. The water vapor penetration did not differ between films and the degradation in water was reduced from 40 to 5% as MFC/NFC was added. There were no differences for contact angle and wettability, but all films showed high resistance to fat penetration. Films with MFC/NFC contents between 75 and 100% showed higher values for tensile strength (50 to 65 MPa) and Young's modulus (6 to 10 MPa) and lower elongation at break (1 to 2%). The experimental results indicated that films with MFC/NFC contents above 50% have potential to be used as packaging material.

Recent Trends in Assessment of Cellulose Derivatives in Designing Novel and Nanoparticulate-Based Drug Delivery Systems for Improvement of Oral Health

Natural polymers are revolutionizing current pharmaceutical dosage forms design as excipient and gained huge importance because of significant influence in formulation development and drug delivery. Oral health refers to the health of the teeth, gums, and the entire oral-facial system that allows us to smile, speak, and chew. Since years, biopolymers stand out due to their biocompatibility, biodegradability, low toxicity, and stability. Polysaccharides such as cellulose and their derivatives possess properties like novel mechanical robustness and hydrophilicity that can be easily fabricated into controlled-release dosage forms. Cellulose attracts the dosage design attention because of constant drug release rate from the precursor nanoparticles. This review discusses the origin, extraction, preparation of cellulose derivatives and their use in formulation development of nanoparticles having multidisciplinary applications as pharmaceutical excipient and in drug delivery, as bacterial and plant cellulose have great potential for application in the biomedical area, including dentistry, protein and peptide delivery, colorectal cancer treatment, and in 3D printable dosage forms.

Polysaccharide-Based Active Coatings Incorporated with Bioactive Compounds for Reducing Postharvest Losses of Fresh Fruits

This review reports recently published research related to the application of polysaccharide-based biodegradable and edible coatings (BECs) fortified with bioactive compounds obtained from plant essential oils (EOs) and phenolic compounds of plant extracts. Combinations of polysaccharides such as starches, pectin, alginate, cellulose derivatives, and chitosan with active compounds obtained from clove, lemon, cinnamon, lavender, oregano, and peppermint have been documented as potential candidates for biologically active coating materials for retardation of quality changes in fresh fruits. Additionally, polysaccharide-based active coatings supplemented with plant extracts such as cashew leaves, pomegranate peel, red roselle, apple fiber, and green tea extracts rich in phenolic compounds and their derivatives have been reported to be excellent substituents to replace chemically formulated wax coatings. Moreover, EOs and plant polyphenolics including alcohols, aldehydes, ketones phenols, organic acids, terpenes, and esters contain hydroxyl functional groups that contribute bioactivity to BECs against oxidation and reduction of microbial load in fresh fruits. Therefore, BECs enriched with active compounds from EOs and plant extracts minimize physiological and microbial deterioration by reducing moisture loss, softening of flesh, ripening, and decay caused by pathogenic bacterial strains, mold, or yeast rots, respectively. As a result, shelf life of fresh fruits can be extended by employing active polysaccharide coatings supplemented with EOs and plant extracts prior to postharvest storage.

Nano-SiO2/hydroxyethyl cellulose nanocomposite used for 210 °C sedimentation control of petroleum drilling fluid

Cellulose derivatives are widely applied in the field of oil and gas exploration. However, this kind of natural polymers always shows poor temperature resistance due to their organic nature. To improve the temperature resistance of hydroxyethyl cellulose (HEC), inorganic nano-SiO2 was introduced onto HEC polymer chains through the silylation coupling technique. And Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectrum (XPS), and thermogravimetic analysis (TGA) were used to analyze the nanocomposite. As a result, nano-SiO2 particle is chemically coupled onto hydroxyethyl cellulose molecule, and nano-SiO2/hydroxyethyl cellulose nanocomposite (RJ-HEC) shows excellent thermal stability comparing with HEC polymer. In experiment, thermal aging tests were utilized, and test results suggest that nano-SiO2/hydroxyethyl cellulose (RJ-HEC) nanocomposite can be utilized as thickening agent of water-based drilling fluid, which shows improved rheology stability at 210 °C and excellent salt (NaCl) tolerance.