Schiff base synergized with protonation of PEI to achieve smart antibacteria of nanocellulose packaging films

Preparation of amino-functionalized yeast/yam starch composite adsorption gel and its mechanism for the adsorption of Congo red and copper ions

Water resource pollution is a major global challenge that poses a serious threat to human health and the environment. In this study, glutaraldehyde was used to cross-link polyethyleneimine (PEI) with yeast and starch. The PEI-modified yeast was attached to the yam starch adsorption gel using the gel properties of starch to prepare a novel starch-based composite adsorbent material (NH2(Gl)-YSA@SZ410). Owing to its porous interconnected structure, the material exhibited optimal adsorption performance, wettability, and mechanical properties. NH2(Gl)-YSA@SZ410 could remove Congo red (CR), Cu2+, and coexisting pollutants (CR and Cu2+ mixture) from solutions. At 308 K, in single CR- or Cu2+-contaminated solutions, the maximum adsorption capacities were 293.52 and 50.34 mg/g, respectively, whereas in the binary-pollutant system, the maximum adsorption capacities were 363.15 and 149.50 mg/g, respectively. Additionally, an in-depth study of single-pollutant and binary-pollutant systems was conducted using adsorption kinetics, isotherms, and adsorption mechanisms. Theoretical calculations indicated that CR and Cu2+ interacted with NH2(Gl)-YSA@SZ410 composite materials through forces such as hydrogen bonding and electrostatic interactions. Furthermore, NH2(Gl)-YSA@SZ410 exhibited excellent stability and practicality. The adsorbent can be effectively applied to wastewater containing both heavy metals and dyes, offering novel ideas for biobased adsorbents.

UV-induced plasma welding and interface customization strategy of cellulose nanofiber/silver nanowire composite electrode for advanced flexible photoelectric applications

Significant advancements in flexible photoelectric devices have been achieved through extensive research on flexible transparent conductive electrodes (FTCEs) based on silver nanowires (AgNWs). However, two key challenges that need to be addressed are the high contact resistance of AgNWs and poor interface adhesion between AgNWs and the flexible substrate. In this study, we present a composite electrode comprising polydopamine-grafted cellulose nanofibers (PDA-TCNF) and AgNWs, fabricated through an interface customization strategy combined with UV-induced plasma welding. To enhance interfacial crosslinking, N, N-bis(acryloyl)cysteamine (BACA) was introduced as a surface adsorbate for AgNWs. The composite electrode exhibited rapid plasma welding of AgNWs under low-intensity UV irradiation. The optimized PDA-TCNF/AgNW-S/3 electrode demonstrated a sheet resistance of 7.26 Ω sq.-1 with a remarkable light transmittance of 85.7 %. The interface customization strategy facilitated enhanced diffusion of silver atoms at AgNW junctions during UV-induced heating, thereby strengthening their welding capability. These electrodes serve as high-performance FTCEs for electroluminescent devices and transparent electric heaters. Our work proposes a simple method to fabricate superior FTCEs by integrating nanocellulose with AgNWs, offering a promising environmentally friendly material for flexible optoelectronic applications.

Structural Elucidation of Heteropolysaccharides from the Peach-Shaped Dictyophora indusiata and Its Anti-Inflammatory Activity

Dictyophora indusiata is commonly utilized as a functional food in China and other Asian countries. The peach-shaped phase of this fungus is nutritionally and taste-wise similar to its mature fruiting bodies. However, there is limited research on the polysaccharides found in the peach-shaped D. indusiata. A heteropolysaccharide was extracted from the volva of peach-shaped D. indusiata (DIVP). Analyses using high-performance gel permeation chromatography, methylation and NMR revealed that DIVP comprises glucose, glucuronic acid, galactose, and mannose. Its structure features a backbone that consists of →3)-β-D-Glcp-(1→ units with branches at →4)-β-D-Glcp-(1→, →6)-α-D-Galp-(1→ and terminal α-Manp-(1→ residues. Physicochemical assessments including X-ray diffraction, thermal, zeta potential and viscosity characterization indicated that DIVP is a semi-crystalline polymer exhibiting excellent physical and thermal stability. Cytokine antibody array and proteome profiler human phosphokinase analyses demonstrated that DIVP downregulates the expression levels of cytokines and alters the phosphorylation status of 16 proteins in human U937 macrophages induced by lipopolysaccharides, indicating its anti-inflammatory activity. These findings suggest that the polysaccharide from the volva of peach-shaped D. indusiata is primarily composed of β-1,3-glucan, which exhibits stable physicochemical properties and anti-inflammatory activity, providing a foundation for its potential use as an anti-inflammatory agent or functional food.

Optimisation of stimuli-responsive films based on dynamic α,β-unsaturated imines from chitosan and trans-2-hexenal to enhance the antimicrobial acid-response

Trans-2-hexenal (HX) is a potent antimicrobial which can be reversibly stabilised in chitosan (CS) films forming α,β-unsaturated imines. The hydrolysis of the imines promoted by acid environments triggers the release of HX to the media exerting its antimicrobial activity. It is known that besides imines, the electrophilic β-alkene carbon of HX can form Michael adducts with primary amino groups of chitosan. However, the formation of nucleophile-C bonds is undesired since these bonds are barely hydrolysed and limit the release of HX and by hence, the effectivity of the film. Thus, the aim of this work has been to optimise the formation of trans-2-hexenal-imine-chitosan films employing response surface methodology in order to favour the formation of conjugated imines avoiding Michael adducts. The optimisation of the reaction parameters indicated that synthesis temperature of 10 °C and without the use of an acid catalyst favours the formation of conjugated imines. Spectroscopic techniques, elemental analysis and swelling behaviour in various media were used to characterise the optimised films. The release kinetics of HX and the antimicrobial activity of the films were also studied. The present work provided relevant information to increase the antimicrobial efficacy of trans-2-hexenal-imine-chitosan films for the development of active food packaging.

Chitosan-based antibacterial AIE luminogens for bioimaging and dual-mode detecting of nitrite in food samples

The polysaccharides are abundant in nature and are typically considered harmless. They can be chemically modified to exhibit a diverse range of fluorescent behaviors. Moreover, these characteristics render polysaccharides particularly promising future for the development of environmentally friendly materials, such as chemical sensors. In this study, a chitosan-based dual-mode sensor (CS-DAS) with aggregation-induced emission (AIE) properties was designed for both fluorometric and colorimetric detection of nitrite. The unique AIE property of CS-DAS enables enhanced fluorescence in aggregated states, overcoming conventional quenching limitations. CS-DAS also showed high selectivity and sensitivity for nitrite detection. By fluorescence and colorimetry, the limits of detection were calculated to be 0.021 μM (1.45 mg/kg) and 0.027 μM (1.86 mg/kg), respectively. This sensor was successfully utilized for the detection of nitrite in sausage samples. Additionally, it exhibited significant antibacterial activity against typical Gram-positive and Gram-negative bacteria. Moreover, CS-DAS showed low cytotoxicity, demonstrating its potential as an excellent fluorescent probe for cell imaging applications.

Composite Films Based on Linear Polyethyleneimine Polymer and Starch or Polysaccharides from DDGS: Synthesis, Characterization, and Antimicrobial Studies

Different films were synthesized from starch or polysaccharides extracted from distillers dried grains with soluble (DDGS) in combination with different percentages of linear polyethyleneimine (PEI) hydrochloride polymer to assess the mechanical and antimicrobial properties of the resulting composites. Moreover, a simple method for the extraction of the polysaccharide content from DDGS is reported. The materials obtained were characterized by ATR-FTIR, NMR, and XPS spectroscopy, swelling capacity, and by organic elemental analysis. In particular, the stability of the film prepared with only DDGS in copper ion solutions was improved by the incorporation of PEI. 13C HRMAS NMR studies evidenced the incorporation of the PEI polymer in the new films. Moreover, the release of PEI molecules from the films was studied by 1H NMR experiments in D2O to explain the antimicrobial properties of the PEI-based films against Staphylococcus aureus, with the DDGS-10% PEI films being the most active surface. Furthermore, the incorporation of copper ions into the different films enhanced their antimicrobial activity. Additionally, the starch-10% PEI film exhibited good swelling capacity in deionized water (~1500%), which decreased with the addition of salts (~250%). Instead, the DDGS-10% PEI film showed low swelling capacity in deionized water (~80%), with this capacity increasing with the addition of salts (~250%). The mechanical properties of the films improved considerably when 3% PEI was used.

A Simple and Cost-Effective FeCl3-Catalyzed Functionalization of Cellulose Nanofibrils: Toward Adhesive Nanocomposite Materials for Medical Implants

In the present work, we explored Lewis acid catalysis, via FeCl3, for the heterogeneous surface functionalization of cellulose nanofibrils (CNFs). This approach, characterized by its simplicity and efficiency, facilitates the amidation of nonactivated carboxylic acids in carboxymethylated cellulose nanofibrils (c-CNF). Following the optimization of reaction conditions, we successfully introduced amine-containing polymers, such as polyethylenimine and Jeffamine, onto nanofibers. This introduction significantly enhanced the physicochemical properties of the CNF-based materials, resulting in improved characteristics such as adhesiveness and thermal stability. Reaction mechanistic investigations suggested that endocyclic oxygen of cellulose finely stabilizes the transition state required for further functionalization. Notably, a nanocomposite, containing CNF and a branched low molecular weight polyethylenimine (CNF-PEI 800), was synthesized using the catalytic reaction. The composite CNF-PEI 800 was thoroughly characterized having in mind its potential application as coating biomaterial for medical implants. The resulting CNF-PEI 800 hydrogel exhibits adhesive properties, which complement the established antibacterial qualities of polyethylenimine. Furthermore, CNF-PEI 800 demonstrates its ability to support the proliferation and differentiation of primary human osteoblasts over a period of 7 days.

Current progress in functionalization of cellulose nanofibers (CNFs) for active food packaging

There is a growing interest in utilizing renewable biomass resources to manufacture environmentally friendly active food packaging, against the petroleum-based polymers. Cellulose nanofibers (CNFs) have received significant attention recently due to their sustainability, biodegradability, and widely available sources. CNFs are generally obtained through chemical or physical treatment, wherein the original surface chemistry and interfacial interactions can be changed if the functionalization process is applied. This review focuses on promising and sustainable methods of functionalization to broaden the potential uses of CNFs in active food packaging. Novel aspects, including functionalization before, during and after cellulose isolation, and functionalization during and after material processing are addressed. The CNF-involved structural construction including films, membranes, hydrogels, aerogels, foams, and microcapsules, is illustrated, which enables to explore the correlations between structure and performance in active food packaging. Additionally, the enhancement of CNFs on multiple properties of active food packaging are discussed, in which the interaction between active packaging systems and encapsulated food or the internal environment are highlighted. This review emphasizes novel approaches and emerging trends that have the potential to revolutionize the field, paving the way for advancements in the properties and applications of CNF-involved active food packaging.

Unlocking sustainable solutions: Nanocellulose innovations for enhancing the shelf life of fruits and vegetables - A comprehensive review

Regarding food security and waste reduction, preserving fruits and vegetables is a vital problem. This comprehensive study examines the innovative potential of coatings and packaging made of nanocellulose to extend the shelf life of perishable foods. The distinctive merits of nanocellulose, which is prepared from renewable sources, include exceptional gas barrier performance, moisture retention, and antibacterial activity. As a result of these merits, it is a good option for reducing food spoilage factors such as oxidation, desiccation, and microbiological contamination. Nanocellulose not only enhances food preservation but also complies with industry-wide environmental objectives. This review explores the many facets of nanocellulose technology, from its essential characteristics to its use in the preservation of fruits and vegetables. Furthermore, it deals with vital issues including scalability, cost-effectiveness, and regulatory constraints. While the use of nanocellulose in food preservation offers fascinating potential, it also wants to be cautiously careful to assure affordability, effectiveness, and safety. To fully use the potential of nanocellulose and advance the sustainability plan in the food business, collaboration between scientists, regulatory bodies, and industry stakeholders is important as we stand on the cusp of a revolutionary era in food preservation.