TEMPO-oxidized cellulose nanofibril film from nano-structured bacterial cellulose derived from the recently developed thermotolerant Komagataeibacter xylinus C30 and Komagataeibacter oboediens R37-9 strains

Cellulose nanofibril/titanate nanofiber modified with CdS quantum dots hydrogel with 3D porous structure: A stable photocatalytic adsorbent for Cr(VI) removal

A novel cellulose nanofibril/titanate nanofiber modified with CdS quantum dots hydrogel (CTH) was synthesized as an effective, stable, and recyclable photocatalytic adsorbent using cellulose nanofibril (CN), titanate nanofiber (TN), and CdS quantum dots. Within the CTH structure, CN formed an essential framework, creating a three-dimensional (3D) porous structure that enhanced the specific surface area and provided abundant adsorption sites for Cr(VI). Simultaneously, TN modified with CdS quantum dots (TN-CdS) served as a nanoscale Z-type photocatalyst, facilitating the efficient separation of photoinduced electrons and holes, further increasing the photocatalytic efficiency. The morphological, chemical, and optical properties of CTH were thoroughly characterized. The CTH demonstrated the maximum theoretical adsorption capacity of 373.3 ± 14.2 mg/g, which was 3.4 times higher than that of CN hydrogel. Furthermore, the photocatalytic reduction rate constant of the CTH was 0.0586 ± 0.0038 min-1, which was 6.4 times higher than that of TN-CdS. Notably, CTH displayed outstanding stability, maintaining 84.9 % of its initial removal efficiency even after undergoing five consecutive adsorption-desorption cycles. The remarkable performance of CTH in Cr(VI) removal was attributed to its 3D porous structure, comprising CN and TN-CdS. These findings provide novel insights into developing a stable photocatalytic adsorbent for Cr(VI) removal.

Computer chip-inspired design of nanocellulose/carbon dots hydrogel as superior intensifier of nano-sized photocatalyst for effective Cr(VI) removal

Hydrogel, a common carrier of photocatalyst that suffers from compromised catalytic efficiency, is still far from practical application. Herein, based on "computer chip-inspired design", a novel nanocellulose/carbon dots hydrogel (NCH) was fabricated as superior intensifier instead of common carrier of sodium titanate nanofibre (STN), where carbon dots (CDs) enhanced amino group-induced adsorption for Cr(VI), promoted photocatalytic properties of STN via transferring the photogenerated electron-hole pairs and improved amino group-induced desorption for reduced product (Cr(III)) via electrostatic repulsion, showing an efficiency of 1 + 1 > 2. Adsorption and photocatalysis experiments demonstrated superior removal performance of the NCH incorporating STN, as shown by theoretical maximum adsorption capacity of 425.74 mg/g and kinetic constant of 0.0374 min^-1 in the photocatalytic process, which was nearly 6.6 and 7.3 times of STN. A series of experiments was conducted to confirm the novel mechanism of CDs-enhanced adsorption-photocatalysis-desorption synergy. This work not only provides new insights into the fabrication of a superior intensifier for nanosized photocatalyst, but also proposes one new mechanism of CDs-enhanced adsorption-photocatalysis-desorption synergy, which is helpful for designing and optimizing nanosized photocatalyst.

Ionic liquid-mediated regeneration of cellulose dramatically improves decrystallization, TEMPO-mediated oxidation and alkyl/alkenyl succinylation

This work demonstrated a successful strategy that simple ionic liquids (ILs) mediated pretreatment could effectively reduce crystallinity of cellulose from 71 % to 46 % (by C₂MIM.Cl) and 53 % (by C₄MIM.Cl). The IL-mediated regeneration of cellulose greatly promoted its reactivity for TEMPO-catalyzed oxidation, which the resulting COO^- density (mmol/g) increased from 2.00 for non-IL-treated cellulose to 3.23 (by C₂MIM.Cl) and 3.42 (C₄MIM.Cl); and degree of oxidation enhanced from 35 % to 59 % and 62 %, respectively. More significantly, the yield of oxidized cellulose increased from 4 % to 45-46 %, by 11-fold. IL-regenerated cellulose can also be directly subjected to alkyl/alkenyl succinylation without TEMPO-mediated oxidation, producing nanoparticles with properties similar to oxidized celluloses (55-74 nm in size, -70-79 mV zeta-potential and 0.23-0.26 PDI); but in a much higher overall yield (87-95 %) than IL-regeneration-coupling-TEMPO-oxidation (34-45 %). Alkyl/alkenyl succinylated TEMPO-oxidized cellulose showed 2-2.5 times higher ABTS* scavenging ability than non-oxidized cellulose; however, alkyl/alkenyl succinylation also resulted in a significant decline in Fe²⁺ chelating property.

Emerging Food Packaging Applications of Cellulose Nanocomposites: A Review

Cellulose is the most abundant biopolymer on Earth, which is synthesized by plants, bacteria, and animals, with source-dependent properties. Cellulose containing β-1,4-linked D-glucoses further assembles into hierarchical structures in microfibrils, which can be processed to nanocellulose with length or width in the nanoscale after a variety of pretreatments including enzymatic hydrolysis, TEMPO-oxidation, and carboxymethylation. Nanocellulose can be mainly categorized into cellulose nanocrystal (CNC) produced by acid hydrolysis, cellulose nanofibrils (CNF) prepared by refining, homogenization, microfluidization, sonification, ball milling, and the aqueous counter collision (ACC) method, and bacterial cellulose (BC) biosynthesized by the Acetobacter species. Due to nontoxicity, good biodegradability and biocompatibility, high aspect ratio, low thermal expansion coefficient, excellent mechanical strength, and unique optical properties, nanocellulose is utilized to develop various cellulose nanocomposites through solution casting, Layer-by-Layer (LBL) assembly, extrusion, coating, gel-forming, spray drying, electrostatic spinning, adsorption, nanoemulsion, and other techniques, and has been widely used as food packaging material with excellent barrier and mechanical properties, antibacterial activity, and stimuli-responsive performance to improve the food quality and shelf life. Under the driving force of the increasing green food packaging market, nanocellulose production has gradually developed from lab-scale to pilot- or even industrial-scale, mainly in Europe, Africa, and Asia, though developing cost-effective preparation techniques and precisely tuning the physicochemical properties are key to the commercialization. We expect this review to summarise the recent literature in the nanocellulose-based food packaging field and provide the readers with the state-of-the-art of this research area.

Biodegradable active packaging: Components, preparation, and applications in the preservation of postharvest perishable fruits and vegetables

The consumption of fresh fruits and vegetables is restricted by the susceptibility of fresh produce to deterioration caused by postharvest physiological and metabolic activities. Developing efficient preservation strategies is thus among the most important scientific issues to be urgently addressed in the field of food science. The incorporation of active agents into a polymer matrix to prepare biodegradable active packaging is being increasingly explored to mitigate the postharvest spoilage of fruits and vegetables during storage. This paper reviews the composition of biodegradable polymers and the methods used to prepare biodegradable active packaging. In addition, the interactions between bioactive ingredients and biodegradable polymers that can lead to plasticizing or cross-linking effects are summarized. Furthermore, the applications of biodegradable active (i.e., antibacterial, antioxidant, ethylene removing, barrier, and modified atmosphere) packaging in the preservation of fruits and vegetables are illustrated. These films may increase sensory acceptability, improve quality, and prolong the shelf life of postharvest products. Finally, the challenges and trends of biodegradable active packaging in the preservation of fruits and vegetables are discussed. This review aims to provide new ideas and insights for developing novel biodegradable active packaging materials and their practical application in the preservation of postharvest fruits and vegetables.

Multifunctional applications of natural polysaccharide starch and cellulose: An update on recent advances

The emergence of clinical complications and therapeutic challenges for treating various diseases necessitate the discovery of novel restorative functional materials. Polymer-based drug delivery systems have been extensively reported in the last two decades. Recently, there has been an increasing interest in the progression of natural biopolymers based controlled therapeutic strategies, especially in drug delivery and tissue engineering applications. However, the solubility and functionalisation due to their complex network structure and intramolecular bonding seem challenging. This review explores the current advancement and prospects of the most promising natural polymers such as cellulose, starch and their derivatives-based drug delivery vehicles like hydrogels, films and composites, in combating major ailments such as bone infections, microbial infections, and cancers. In addition, selective drug targeting using metal-drug (MD) and MD-based polymeric missiles have been exciting but challenging for its application in cancer therapeutics. Owing to high biocompatibility of starch and cellulose, these materials have been extensively evaluated in biomedical and pharmaceutical applications. This review presents a detailed impression of the current trends for the construction of biopolymer-based tissue engineering, drug/gene/protein delivery vehicles.