Ionic Liquid-Mediated Homogeneous Esterification of Cinnamic Anhydride to Xylans

Xylan cinnamoylation for reinforcing poly (butylene adipate-co-terephthalate): Molecule design and interaction optimization

PBAT composites with biomass fillers have gained considerable attention as alternatives to non-biodegradable plastics. This work employed xylan derivatives as fillers for PBAT composites. Xylan was modified by introducing cinnamoyl side groups which limit the hydrogen bonding and construct π-π stacking interactions with PBAT chains. The resultant xylan cinnamates (XCi) show degree of substitution (DS) of 0.55-1.89, glass-transition temperatures (Tg) of 146.5-175.0 °C and increased hydrophobicity, which can be simply controlled by varying the molar ratio of reactants. NMR results demonstrate that the C3-OH of xylopyranosyl unit is more accessible to cinnamoylation. XCi fillers (30-50 wt%) were incorporated into PBAT through melt compounding. The filler with a DS of 0.97 exhibited the optimal reinforcing effect, showing superior tensile strength (19.4 MPa) and elongation at break (330.9 %) at a high filling content (40 wt%), which is even beyond the neat PBAT. SEM and molecular dynamics simulation suggest improved compatibility and strengthened molecular interaction between XCi and PBAT, which explains the suppressed melting/crystallization behavior, the substantial increase in Tg (-34.5 → -1.8 °C) and the superior mechanical properties of the composites. This research provides valuable insights into the preparation of high-performance composites by designing the molecular architecture of xylan and optimizing the associated interactions.

Synthesis and antitumor activity of bagasse xylan derivatives modified by graft-esterification and cross-linking

A crucial aspect in achieving sustainable development of biomass materials is the modification of renewable polysaccharides to create various high-value functional materials. In this paper, bagasse xylan (BX) was used as a raw material to introduce benzyl methacrylate (BMA) through graft copolymerization reaction to generate the intermediate product BX-g-BMA. Subsequently, the target product (CA-BX-g-BMA) was synthesized by catalytic esterification of BX-g-BMA with citric acid (CA) in AmimCl ionic liquid. Meanwhile, the characterization and bioactivity studies of CA-BX-g-BMA were carried out. The graft copolymerization and esterification reactions induced significant changes in the morphological structure of BX and obviously improved its thermal stability and crystallinity. The application of density functional theory (DFT), molecular electrostatic potential (MEP) and molecular docking has revealed that CA-BX-g-BMA possesses multiple active sites, strong biological activity and a strong binding affinity to 6RCF tumor protein with a binding energy of -32.26 kJ/mol. The in vitro antitumor activity of this novel derivative was tested by MTT assay, and the results showed that CA-BX-g-BMA was non-toxic to normal cells and inhibited MDA-MB-231 (breast cancer cells) by up to 32.16 % ± 4.89 %, which is approximately 11 times higher than that of BX. The exploration of these properties is essential to promote future multidisciplinary applications of BX derivatives.

Green Approaches on Modification of Xylan Hemicellulose to Enhance the Functional Properties for Food Packaging Materials-A Review

Based on the environmental concerns, the utilisation of hemicelluloses in food packaging has become a sustainable alternative to synthetic polymers and an important method for the efficient utilisation of biomass resources. After cellulose, hemicellulose is a second component of agricultural and forestry biomass that is being taken advantage of given its abundant source, biodegradability, nontoxicity and good biocompatibility. However, due to its special molecular structure and physical and chemical characteristics, the mechanical and barrier properties of hemicellulose films and coatings are not sufficient for food packaging applications and modification for performance enhancement is needed. Even though there are many studies on improving the hydrophobic properties of hemicelluloses, most do not meet environmental requirements and the chemical modification of these biopolymers is still a challenge. The present review examines emerging and green alternatives to acetylation for xylan hemicellulose in order to improve its performance, especially when it is used as biopolymer in paper coatings or films for food packaging. Ionic liquids (ILs) and enzymatic modification are environmentally friendly methods used to obtain xylan derivatives with improved thermal and mechanical properties as well as hydrophobic performances that are very important for food packaging materials. Once these novel and green methodologies of hemicellulose modifications become well understood and with validated results, their production on an industrial scale could be implemented. This paper will extend the area of hemicellulose applications and lead to the implementation of a sustainable alternative to petroleum-based products that will decrease the environmental impact of packaging materials.

Synthesis, Characterization and Bioactivity Evaluation of a Novel Nano Bagasse Xylan/Andrographolide Grafted and Esterified Derivative

In the in-depth research that has been conducted on nanometer biomaterials, how to use the biomass resources with high activity and low toxicity to prepare nanomaterials for biomedical applications has attracted much attention. To realize efficient and comprehensive utilization of biomass, bagasse xylan/andrographolide (BX/AD) was ued as a raw material and glycyrrhetinic acid (GA) as an esterification agent to synthesize bagasse xylan/andrographolide esterified derivative (GA-BX/AD). Then, the bagasse xylan/andrographolide grafted and esterified derivative (GA-BX/AD-g-IA) was synthesized by the graft crosslinking reactions using itaconic acid (IA) as graft monomer. The better synthesis conditions were optimized by single factor experiments, the degree of esterification substitution (DS) was 0.43, and the grafting rate (G) of the product reached 42%. The structure and properties of the product were characterized by FTIR, XRD, DTG, SEM, and ¹H NMR. The results showed that the product morphology was significantly changed, and the nanoparticles were spherical with a particle size of about 100 nm. The anti-cancer activity of the product was measured. The molecular docking simulations revealed that the product had good docking activity with human glucocorticoid protein (6CFN) with a binding free energy of 14.38 kcal/mol. The MTT assay showed that the product had a strong inhibitory effect on the growth of human liver cancer cells (BEL-7407) and gastric cancer cells (MGC80-3), with inhibition ratio of 38.41 ± 5.32% and 32.69 ± 4.87%. Therefore, this nanomaterial is expected to be applied to the development and utilization of drug carriers and functional materials.

Anionic structural effect on the dissolution of arabinoxylan-rich hemicellulose in 1-butyl-3-methylimidazolium carboxylate-based ionic liquids

The exploration of a highly efficient and environment-friendly solvent for dissolving hemicellulose is significant. In this study, 1-butyl-3-methylimidazolium carboxylate ([Bmim]carboxylate)-based ionic liquids (ILs), including [Bmim]formate, [Bmim]acetate, [Bmim]propionate, and [Bmim]butyrate, were used as solvents to dissolve arabinoxylan-rich hemicellulose from bamboo. The hemicellulose solubility in the ILs was determined as a function of temperature. The interaction between the hemicellulose and the ILs was evaluated by using ¹H and ¹³C NMR techniques. The hemicelluloses regenerated from the saturated IL solutions were characterized. Results showed that the temperature and structure of carboxylate anions deeply affected the hemicellulose solubility. The carboxylate anion played a more important role than the imidazolium cation in hemicellulose dissolution. The hydrogen bond that formed between the ILs and the hydroxyl groups at the XC2 position of xylopyranose units of hemicellulose was stronger than that between the ILs and the hydroxyl groups at XC3 position of xylopyranose units. The hydrogen bond strength between the hemicellulose and the ILs was affected by the alkyl chain of the carboxylate anion and the hemicellulose concentration. The disruption of the inter- and intra-molecular hydrogen bonds in hemicellulose by the ILs was responsible for the hemicellulose dissolution. The main chain of hemicellulose remained nearly unchanged during the dissolution process.

The exploration of a highly efficient and environment-friendly solvent for dissolving hemicellulose is significant.