High-yield production of rod-like and spherical nanocellulose by controlled enzymatic hydrolysis of mechanically pretreated cellulose

Nanocellulose Composite Films in Food Packaging Materials: A Review

Owing to the environmental pollution caused by petroleum-based packaging materials, there is an imminent need to develop novel food packaging materials. Nanocellulose, which is a one-dimensional structure, has excellent physical and chemical properties, such as renewability, degradability, sound mechanical properties, and good biocompatibility, indicating promising applications in modern industry, particularly in food packaging. This article introduces nanocellulose, followed by its extraction methods and the preparation of relevant composite films. Meanwhile, the performances of nanocellulose composite films in improving the mechanical, barrier (oxygen, water vapor, ultraviolet) and thermal properties of food packaging materials and the development of biodegradable or edible packaging materials in the food industry are elaborated. In addition, the excellent performances of nanocellulose composites for the packaging and preservation of various food categories are outlined. This study provides a theoretical framework for the development and utilization of nanocellulose composite films in the food packaging industry.

Preparation of nanocellulose and its applications in wound dressing: A review

Nanocellulose, as a nanoscale polymer material, has garnered significant attention worldwide due to its numerous advantages including excellent biocompatibility, thermal stability, non-toxicity, large specific surface area, and good hydrophilicity. Various methods can be employed for the preparation of nanocellulose. Traditional approaches such as mechanical, chemical, and biological methods possess their own distinct characteristics and limitations. However, with the growing deterioration of our living environment, several green and environmentally friendly preparation techniques have emerged. These novel approaches adopt eco-friendly technologies or employ green reagents to achieve environmental sustainability. Simultaneously, there is a current research focus on optimizing traditional nanocellulose preparation methods while addressing their inherent drawbacks. The combination of mechanical and chemical methods compensates for the limitations associated with using either method alone. Nanocellulose is widely used in wound dressings owing to its exceptional properties, which can accelerate the wound healing process and reduce patient discomfort. In this paper, the principle, advantages and disadvantages of each preparation method of nanocellulose and the research findings in recent years are introduced Moreover, this review provides an overview of the utilization of nanocellulose in wound dressing applications. Finally, the prospective trends in its development alongside corresponding preparation techniques are discussed.

Enzymatic pretreatment for cellulose nanofiber production: Understanding morphological changes and predicting reducing sugar concentration

Enzymatic pretreatment plays a crucial role in producing cellulose nanofibers (CNFs) before fibrillation. While previous studies have explored how treatment severity affects CNF characteristics, there remains a lack of suitable parameters to monitor real-time enzymatic processes and fully comprehend the link between enzymatic action, fibrillation, and CNF properties. This study focuses on evaluating the impact of enzyme charge (using a monocomponent endoglucanase) and treatment time on cellulose fiber morphology and reducing sugar generation. For the first time, a random forest (RF) model is developed to predict reducing sugar concentration based on easily measurable process conditions (e.g., stirrer power consumption) and fiber/suspension characteristics like fines content and apparent viscosity. Polarized light optical microscopy was found to be a suitable technique to evaluate the morphological changes that fibers experience during enzymatic pretreatment. The research also revealed that endoglucanases initially induce surface fibrillation, releasing fine fibers into the suspension, followed by fiber swelling and shortening. Furthermore, the effect of enzymatic pretreatment on resulting CNF characteristics was studied at two fibrillation intensities, indicating that a high enzyme charge and short treatment times (e.g., 90 min) are sufficient to produce CNFs with a nanofibrillation yield of 19-23 % and a cationic demand ranging from 220 to 275 μeq/g. This work introduces a well-modeled enzymatic pretreatment process, unlocking its potential and reducing uncertainties for future upscaling endeavors.

Hydrophobic enzymatic cellulose nanocrystals via a novel, one-pot green method

Cellulose nanocrystals (CNCs) are a rapidly growing bionanomaterial with remarkable properties that have been harnessed in various applications, including mechanical reinforcement, biomedical materials, and coatings. However, for non-water-based applications, hydrophobization of CNCs while preserving their integrity is crucial. In this study, we propose a new eco-friendly, one-pot surface esterification method for hydrophobizing enzymatic CNCs in aqueous suspension without solvent exchange. By establishing an appropriate set of reaction conditions, it was possible to create a miscibility gradient that enabled a low-cost, and renewable fatty acid to be utilized as an acyl donor and solvent, allowing direct hydrophobic modification of the as-produced aqueous suspension of enzymatic CNC. FT-IR and AFM-IR analyses confirmed the formation of ester groups, while 13C NMR confirmed the emergence of carboxyl groups. XPS revealed a high degree of surface substitution (0.39) in the modified CNC, while a substantial increase in contact angle (from 40 to approximately 90°) quantitatively confirmed the high efficiency of the enzymatic CNC's hydrophobic modification. Additionally, important properties such as morphology remained practically unchanged, except for a slight increase in thermal stability and crystallinity of the CNCs. Therefore, hydrophobic enzymatic CNCs were successfully produced via a simple, scalable, and environmentally friendly approach without compromising their properties. These hydrophobic CNCs have the potential to enhance nanocomposite compatibility, improve packaging performance for electronics and foods, optimize adhesion in coatings, and offer advancements in cosmetics and drug delivery. However, comprehensive studies are needed to confirm their applicability across these sectors.