Preparation of multi-barrier and multi-functional paper-based materials by chitosan, ethyl cellulose and green walnut husk biorefinery products for sustainable food packaging.

The growing interest in paper-based materials for packaging is driven by their renewable and eco-friendly characteristics. However, their poor barrier performance against water, oil, and gas limits their application in the food packaging industry. In this study, we developed a simple dual-layer coating method to create water- and oil-repellent, gas barrier, antioxidant, and antibacterial paper-based materials using naturally-derived materials, including chitosan (CS), ethyl cellulose (EC), and cascade biorefinery products from green walnut husk (GWHE and CNC). The bottom CS/CNC oil-resistant coating and the top EC/GWHE water-resistant coating were applied to the paper surface. The synergistic effect of these coatings enhances the gas barrier and imparts functional properties to the paper. Compared to uncoated paper, the dual-layer-coated paper demonstrated a 239.1 % increase in tensile index, a higher kit rating value of 12/12, a lower Cobb 60 value of 3.21 mg/m2, a 44.0 % decrease in water vapor permeability (WVP), and a 90.7 % reduction in air permeability (AP). Additionally, this coated paper exhibited good antioxidant and antibacterial properties and favorable biodegradability. This study provides novel insights into the valorization of GWH waste and presents a sustainable strategy for producing high-performance paper-based materials for food packaging applications.

Carboxymethyl cellulose-based multifunctional film integrated with polyphenol-rich extract and carbon dots from coffee husk waste for active food packaging applications.

Sustainable carboxymethyl cellulose (CMC)-based active composite films were developed through the addition of polyphenol-rich extract from coffee husk (CHE) and carbon dots (CDs) prepared using the biowaste residue of CHE extraction. The influences of various CDs contents on the physicochemical and functional characteristics of composite films have been researched. The 6% (w/w) CHE and 3% (w/w) CDs were uniformly dispersed within the CMC matrix to produce a homogenous film with enhanced mechanical properties. The CMC/CHE/CDs3% film exhibited outstanding UV-light blocking, improved water and gas barriers, potent antioxidant activity with above 95% DPPH and ABTS scavenging rates, and effective antibacterial capabilities against L. monocytogenes and E. coli. The food packaging experiment demonstrated that this active composite film slowed the rotting of fresh-cut apples and extended their shelf-life to 7 days at 4 °C storage. Therefore, the obtained multifunctional film showed promise as an environmentally friendly food packaging material.

Gelatin-based multifunctional composite films integrated with dialdehyde carboxymethyl cellulose and coffee leaf extract for active food packaging.

In this study, dialdehyde carboxymethyl cellulose (DCMC, 10 wt% based on gelatin) and varying contents of coffee leaf extract (CLE, 1, 3, 5 and 7 wt% based on gelatin) were incorporated into gelatin (GEL) matrix to develop multifunctional food packaging films. DCMC acted as a physical reinforcing filler through crosslinking with GEL matrix by Schiff-base reaction, CLE served as an active filler to confer film functional properties. The micro-morphology, micro-structure, physicochemical and functional properties of the GEL/DCMC/CLE composite film were investigated. The results demonstrated that mechanical, barrier properties and thermal stability of films were significantly improved by incorporation of CLE. Compared with pure GEL film, the GEL/DCMC/5%CLE film exhibited excellent UV light blocking while kept enough transparency, the best mechanical property, water resistance, water vapor and oxygen barrier, as well as thermal stability. GEL/DCMC/5%CLE film also possessed strong antioxidant activity and some antibacterial activity against E. coli and S. aureus. Packaging application testing demonstrated that the resultant GEL/DCMC/5%CLE film effectively delayed the lipid oxidation of walnut oil and preserved the postharvest freshness of fresh walnut kernels under ambient conditions.

Crosslinked fish scale gelatin/alginate dialdehyde functional films incorporated with carbon dots derived from pomelo peel waste for active food packaging.

A multifunctional and environmentally friendly composite film was developed by incorporating pomelo peel-derived carbon dots (PCDs) into a fish scale gelatin (FSG)/alginate dialdehyde (ADA) biopolymer matrix. ADA was used to reinforce the physicomechanical properties of the FSG film via Schiff base crosslinking. PCDs with strong antioxidant and antimicrobial activities were synthesized via a hydrothermal method. The effect of various PCDs content on the surface morphological, physicochemical, and functional characteristics of the composite films was investigated. The results showed that the introduction of PCDs into the FSG/ADA matrix effectively reinforced the mechanical performance, enhanced the water vapor and water resistance, increased UV-light blocking, conferred fluorescence properties, and improved the thermal properties of the composite films. Under 3 wt% PCDs content, the FSG/ADA/PCDs-3 % composite film not only presented significant antioxidant capacity with a radical scavenging rate of 91.71 % for DPPH and approximately 100 % for ABTS, but also exhibited excellent antimicrobial ability against bacteria and fungi. Results of a preservation experiment showed that the prepared FSG/ADA/PCDs-3 % film preserved the physiological qualities of strawberries post-harvest and extended their shelf-life to 7 days at room temperature. Overall, the fabricated FSG/ADA/PCDs composite films are promising for use in eco-friendly active food packaging.

Superhydrophobic cellulose paper with sustained antibacterial activity prepared by in-situ growth of carvacrol-loaded zinc-based metal organic framework nanorods for food packaging application.

Cellulose paper packaging materials have gained considerable attention as substitutes for petroleum-based plastics owing to their biodegradability, renewability, flexibility, and good mechanical strength. However, high hydrophilicity and the absence of essential antibacterial activity limit their application in food packaging. In this study, a facile and energy-saving method was developed to improve the hydrophobicity of cellulose paper and endow it with a long-acting antibacterial effect by integrating cellulose paper substrate with metal-organic frameworks (MOFs). A dense and homogenous coating of regular hexagonal ZnMOF-74 nanorods was in-situ formed on a paper surface by layer-by-layer assembly followed by low-surface-energy polydimethylsiloxane (PDMS) modification to prepare a superhydrophobic PDMS@(ZnMOF-74)5@paper. Excellent anti-fouling, self-cleaning, and antibacterial adhesion performances were obtained for this superhydrophobic paper. In addition, active carvacrol was loaded into the pores of ZnMOF-74 nanorods on PDMS@(ZnMOF-74)5@paper to combine antibacterial adhesion together with bactericidal ability, ultimately resulting in a completely "bacteria-free" surface and sustained antibacterial performance. The resultant superhydrophobic papers not only showed overall migration values within the limit of 10 mg/dm2 but also good stability against various harsh mechanical, environmental, and chemical treatments. This work gave insights into the potential of in-situ-developed MOFs-dopped coating as a functionally modified platform for preparing active superhydrophobic paper-based packaging.

Matrine inhibits synovial angiogenesis in collagen-induced arthritis rats by regulating HIF-VEGF-Ang and inhibiting the PI3K/Akt signaling pathway.

Matrine (Mat) is an alkaloid of tetracycline quinazine, and previous studies have demonstrated its specific effect on relieving rheumatoid arthritis (RA). However, the effect of Mat on joint synovial angiogenesis in the pathogenesis of RA has not been elucidated. In this study, body weight, joint swelling, arthritis index (AI) score, histopathological changes, immunohistochemical, and western blot- were used in collagen-induced arthritis (CIA) rats to detect pro-inflammatory factors and, - expression levels of key cytokines and proteins along the hypoxia-inducible factor (HIF)-endothelial growth factor (VEGF)-angiopoietin (Ang) axis and VEGF-phosphoinositide 3-kinase (PI3K) / protein kinase B (Akt) pathway. In vitro experiments were conducted to observe the effect of Mat on the proliferation, migration and lumen formation of RA-fibroblast-like synovial cells (FLS) and human umbilical vein endothelial cells (HUVECs). Results showed that Mat reduced the degree of paw swelling and AI score in CIA rats, joint synovial tissue proliferation, inflammatory cell infiltration, and neovascularization; moreover, it down-regulated the expression levels of inflammatory factors interleukin-1ß, interferon-γ, and pro-angiogenic factors VEGF, placental growth factor, HIF-α, Ang-1, Ang-2, Tie-2, and phosphorylation-Akt in the ankle joint of CIA rats. In addition, the in vitro experiments showed that Mat inhibited the proliferation and migration of RA-FLS and inhibited the proliferation and lumen formation of HUVECs. Therefore, Mat exerts an anti-angiogenesis effect by regulating the HIF-VEGF-Ang axis and inhibiting the PI3K/Akt signaling pathway. This inhibits the pathogenesis and improve the symptoms of RA, and may be offered as a candidate drug for the treatment of RA.