Antibacterial Janus cellulose/MXene paper with exceptional salt rejection for sustainable and durable solar-driven desalination.

The scarcity of freshwater resources and increasing demand for drinking water have driven the development of durable and sustainable desalination technologies. Although MXene composites have shown promise due to their excellent photothermal conversion and high thermal conductivity, their high hydrophilicity often leads to salt precipitation and low durability. In this study, we present a novel Cellulose (CF)/MXene paper with a Janus hydrophobic/hydrophilic configuration for long-term and efficient solar-driven desalination. The paper features a dual-layer structure, with the upper hydrophobic layer composed of CF/MXene paper exhibiting convexness to serve as a photothermal layer with exceptional salt rejection properties. Simultaneously, the bottom porous layer made of CF acts as an efficient thermal insulation. This unique design effectively minimizes heat loss and facilitates efficient water transportation. The Janus CF/MXene paper demonstrates a high evaporation rate of 1.11 kg m-2h-1 and solar thermal conversion efficiency of 82.52 % under 1 sun irradiation. Importantly, even after 2500 h of operation in a simulated seawater environment, the paper maintains a stable evaporation rate without significant salt deposition and biodegradation due to an antibacterial rate exceeding 90 %. These findings highlight the potential of the Janus CF/MXene paper for scalable manufacturing and practical applications in solar-driven desalination.

Hemicellulose-based nanoaggregate-incorporated biocompatible hydrogels with enhanced mechanical properties and sustained controlled curcumin release behaviors.

Local drug delivery has generated considerable interest due to its controlled and sustained drug release at the target site on demand. Nanoaggregate-incorporated composite hydrogels are desirable as local drug delivery systems; however, it is difficult to achieve sustained and controlled hydrophobic drug release and superior mechanical properties in one system. Herein, a "smart" composite hydrogel was synthesized by incorporating hemicellulose-based nanoaggregates into a double network consisting of alginate/Ca2+ and polyacrylic acid-co-dimethylaminoethyl methacrylate [P(AA-co-DMAEMA)]. Hemicellulose-based nanoaggregates were assembled from xylan-rich hemicellulose laurate methacrylate (XH-LA-MA) polymers and entrapped into the hydrogel framework via chemical fixation. Another composite hydrogel with physically embedded hemicellulose laurate (XH-LA) nanoaggregates was prepared as a comparison. Accordingly, covalently cross-linked XH-LA-MA nanoaggregates in hydrogels resulted in a denser pore structure and reinforced mechanical properties. Nanoaggregate diffusion analysis revealed that covalent bonding between the nanoaggregates and the hydrogel framework contributed to prolonged diffusion behavior. Curcumin (Cur)-loaded XH-LA-MA composite hydrogels enabled sustained Cur release in simulated body fluid and showed stimulus responsiveness toward ethylenediaminetetraacetic acid (EDTA) and/or glutathione (GSH). All the composite hydrogels were biocompatible, as verified by Cell Counting Kit-8 (CCK-8) assay against NIH/3T3 cells. These composite hydrogels hold great potential as a promising dosage form for biomedical applications.

Rapid transesterification of cellulose in a novel DBU-derived ionic liquid: Efficient synthesis of highly substituted cellulose acetate.

Cellulose acetate (CA) is one of the most important cellulose plastics that has demonstrated extensive applications in many areas. In search of a more sustainable and efficient way to prepare CA, we synthesized a novel ionic liquid, [DBUC8]Cl, based on the commonly used catalyst DBU (1,8-diazabicyclo[5.4.0]undecyquin-7-ene) in a simple manner. [DBUC8]Cl can dissolve cellulose more efficiently than the same type of imidazolyl ionic liquid, owing to the stronger alkalinity of DBU. It is noteworthy that highly substituted CA (DS = 2.82) was successfully synthesized via transesterification with alkenyl ester under mild conditions (80 °C, 40 min) without the addition of a catalyst in this solvent, which is superior to most of the reported work. Furthermore, we confirmed that the synthesized CA had good thermoplasticity, and a transparent cellulose acetate film (CAF) was obtained by hot pressing with a small amount of glycerol. Therefore, we propose a new DBU-derived ionic liquid, which may serve as a versatile platform system for producing cellulose-derived bioplastics more sustainably and efficiently.

Efficient Cellulose Dissolution and Film Formation Enabled by Superbase Amino Acid Ionic Liquids.

Cellulose is a promising feedstock for the production of sustainable materials. To fully utilize its potential, exploring efficient cellulose solvents is a paramount prerequisite. In this study, ten superbase amino acid ionic liquids (SAAILs) are synthesized using 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with different amino acid anions via a simple neutralization method. The properties of these SAAILs, such as viscosity and glass transition temperature, varied with their cation and anion structures. The ability of the SAAILs to dissolve cellulose is related to their Kamlet-Taft parameters, particularly hydrogen bond basicity (ß). The main driving force for cellulose dissolution in SAAILs is thought to be hydrogen bonding interactions between SAAILs and cellulose hydroxyl groups. Four SAAILs composed of DBN or DBU cations and proline, or aspartic acid anions are identified as promising solvents for preparing regenerated cellulose films (RCFs). The RCF prepared from [DBN]Proline(Pro) showed a favorable combination of high tensile strength (76.9 MPa), high Young's modulus (5201.2 MPa), good transparency (≈70% at 550 nm), and smooth surface morphology. These halogen- and metal-free SAAILs show the potential to provide a new avenue for cellulose processing.

Self-assembly behavior and conformation of amphiphilic hemicellulose-graft-fatty acid micelles.

In this work, a series of amphiphilic hemicellulose-based grafting polymers are synthesized by homogeneous esterification with various hydrophobic chain fatty acids. With the flexible chain conformation of hemicelluloses, the hemicellulose-graft-fatty acid is self-assembled into hard sphere micelles in aqueous solution through hydrophobic interactions. The resultant micelles show apparent hydrodynamic radius (Rh) varying in the range of 34-57 nm and radius of gyration (Rg) varying from 30 to 44 nm. Moreover, the Rh, Rg, zeta potential and critical micelle concentration (CMC) of the micelles gradually decreases with the increasing hydrophobic chain length. The aggregation number of micelles can be tuned by varying alkyl chain lengths. Taking curcumin (Cur) as a model drug, the hemicellulose micelles were investigated as drug carriers, which exhibit a chain length-controlled drug release behavior. Taken together, structure and property tunable hemicellulose-based micelles were obtained, and showed potential of application in pharmaceutical, food, and cosmetics fields.

Green Fabrication of Highly Conductive Paper Electrodes via Interface Engineering with Aminocellulose.

Herein, a novel, facile, and versatile approach to fabricate highly flexible and conductive paper is proposed by electroless deposition (ELD) with the assistance of aminocellulose as the interface layer. The obtained Cu nanoparticles (NPs)-coated cellulose paper is highly conductive with a significant low resistance of 0.38 Ω sq-1 after only 10 min of ELD treatment. This conductive cellulose paper shows excellent stability when it suffers from bending, folding, and tape adhesion cycles. With the same method, the Cu NPs can also be successfully deposited on the polypropylene (PP)-filled hybrid paper. The conductive paper exhibits very smooth and hydrophobic surface with high reflection, which can be used for special electronic devices. In a word, the fabrication of aminocellulose interface permits a controlled ELD of metal nanoparticles on paper substrate, and this mild and low-cost method opens up new opportunities for large-scale production of flexible and wearable electronics.

Quercetin/chitosan-graft-alpha lipoic acid micelles: A versatile antioxidant water dispersion with high stability.

Natural active compounds with antioxidant properties and other potential health benefits, like quercetin (Qu), have aroused wide concern for developing bio-functional products. However, their applications are hindered by their intrinsic poor water solubility and chemical instability. In this paper, a natural antioxidant alpha lipoic acid (ALA) was grafted onto chitosan (CS) to synthesize a novel graft polymer (CS-graft-ALA). In particular, this graft-polymer could self-assemble into spherical nanomicelles in water, with a low critical micelle concentration (CMC) of 0.0076 mg/mL. As a robust and active nanocarrier, the CS-graft-ALA micelles showed high efficiency in encapsulating Qu and dispersing Qu in water. As found, the antioxidant activity of Qu was effectively enhanced when entrapped within CS-graft-ALA micelles. Moreover, CS-graft-ALA micelles could significantly improve the photo-stability and temperature-stability of Qu. The Qu/CS-graft-ALA micelles with excellent water dispersability, stability and improved antioxidant activity hold a great potential for wide applications.

Rapid self-healing, stretchable, moldable, antioxidant and antibacterial tannic acid-cellulose nanofibril composite hydrogels.

Here, we designed a self-healing composite hydrogel with antioxidant and antibacterial activities by using cellulose nanofibrils (CNF) and tannic acid (TA) as functional additives. Excellent mechanical stability, moldability, stretchability and rapid self-healing ability without any external intervention were realized in one system due to the combined dynamic borate ester bonding between polyvinyl alcohol-borax (PB) and multi-hydrogen bonding between different components. The rheological measurements indicated the incorporation of CNF and TA to PB system substantially affected the viscoelasticity of hydrogels. The unique antioxidant and antibacterial properties were achieved due to the complexation of TA. These high performance multifunctional hydrogels opens a window for a broad application in the field of smart devices and surface engineering.

Self-Assembled Conjugated Polymer/Chitosan-graft-Oleic Acid Micelles for Fast Visible Detection of Aliphatic Biogenic Amines by "Turn-On" FRET.

A fluorescent "turn-on" sensor for fast measurement of aliphatic biogenic amines (BAs) was developed based on fluorescent carboxylated polyfluorene (PFTBTCOOH)/chitosan-graft-oleic acid (CS-graft-OA) micelles. In this system, biobased CS-graft-OA micelles, prepared by graft modification of CS with OA, serve as the vector of the hydrophobic fluorescent probe. Bright turn-on fluorescence was achieved by the intermolecular fluorescence resonance energy transfer of the encapsulated PFTBTCOOH, driven by the formation of an electrostatic complex with aliphatic BAs, which facilitate visual identification. The peak intensity ratio of the PFTBTCOOH/CS-graft-OA micelles toward an increasing amount of aliphatic BAs was calibrated, giving a linear relationship. The fluorescence response of PFTBTCOOH/CS-graft-OA micelles to aliphatic BAs in milk and yogurt matrixes reaches a detection concentration as low as 10 µM, showing that the PFTBTCOOH/CS-graft-OA micelle solution is a potential chemosensor for fast and selective detection of trace aliphatic BAs, which is of great significance to public health and food safety.

Characterization and antioxidant activity of ß-carotene loaded chitosan-graft-poly(lactide) nanomicelles.

ß-Carotene (ß-C) is a well-established natural antioxidant agent, but its poor water-solubility, low chemical stability and low bioavailability limit its application in food, pharmaceuticals and cosmetics industries. Thus it is critical to develop an efficient method to improve the water solubility and stability of ß-C. In this research, amphiphilic chitosan-graft-poly (lactide) (CS-g-PLA) copolymer was synthesized via a homogeneous ring-opening polymerization (ROP) in ionic liquid. The obtained CS-g-PLA copolymer was able to self-assemble into about 14 nm micelles in water at low concentration, and ß-C loaded micelles (ß-C/M) had low ß-C degradation after 15 days. The antioxidant properties of the ß-C/M were investigated by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method and ferric reducing antioxidant power (FRAP) method, respectively. Significantly improved antioxidant activity was observed for ß-C/M in compare with free ß-C. The aqueous dispersion of ß-C/M has potential to be applied in the field of functional food and cosmetics.