Antibacterial tragacanth gum-based nanocomposite films carrying ascorbic acid antioxidant for bioactive food packaging

The Food-Materials Nexus: Next Generation Bioplastics and Advanced Materials from Agri-Food Residues

The most recent strategies available for upcycling agri-food losses and waste (FLW) into functional bioplastics and advanced materials are reviewed and the valorization of food residuals are put in perspective, adding to the water-food-energy nexus. Low value or underutilized biomass, biocolloids, water-soluble biopolymers, polymerizable monomers, and nutrients are introduced as feasible building blocks for biotechnological conversion into bioplastics. The latter are demonstrated for their incorporation in multifunctional packaging, biomedical devices, sensors, actuators, and energy conversion and storage devices, contributing to the valorization efforts within the future circular bioeconomy. Strategies are introduced to effectively synthesize, deconstruct and reassemble or engineer FLW-derived monomeric, polymeric, and colloidal building blocks. Multifunctional bioplastics are introduced considering the structural, chemical, physical as well as the accessibility of FLW precursors. Processing techniques are analyzed within the fields of polymer chemistry and physics. The prospects of FLW streams and biomass surplus, considering their availability, interactions with water and thermal stability, are critically discussed in a near-future scenario that is expected to lead to next-generation bioplastics and advanced materials.

Green Synthesis and Characterization of Carboxymethyl Cellulose Fabricated Silver-Based Nanocomposite for Various Therapeutic Applications

Purpose

The current study proposed the simple, eco-friendly and cost-effective synthesis of carboxymethyl cellulose (CMC) structured silver-based nanocomposite (CMC-AgNPs) using Syzygium aromaticum buds extract.

Methods

The CMC-AgNPs were characterized by ultraviolet (UV) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transmission infra-red (FTIR), energy-dispersive X-ray (EDX), and dynamic light scattering (DLS) techniques. The synthesized nanocomposites were evaluated for their bactericidal kinetics, in-vivo anti-inflammatory, anti-leishmaniasis, antioxidant and cytotoxic activities using different in-vitro and in-vivo models.

Results

The spherical shape nanocomposite of CMC-AgNPs was synthesized with the mean size range of 20–30 nm, and the average pore diameter is 18.2 nm while the mean zeta potential of −31.6 ± 3.64 mV. The highly significant (P < 0.005) antibacterial activity was found against six bacterial strains with the ZIs of 24.6 to 27.9 mm. More drop counts were observed in Gram-negative strains after 10 min exposure with CMC-AgNPs. Significant damage in bacterial cell membrane was also observed in atomic force microscopy (AFM) after treated with CMC-AgNPs. Nanocomposite showed highly significant anti-inflammatory activity in cotton pellet induced granuloma model (Phase I) in rats with the mean inhibitions of 43.13% and 48.68% at the doses of 0.025 and 0.05 mg/kg, respectively, when compared to control. Reduction in rat paw edema (Phase II) was also highly significant (0.025 mg/kg; 42.39%; 0.05 mg/kg, 47.82%). At dose of 0.05 mg/kg, CMC-AgNPs caused highly significant decrease in leukocyte counts (922 ± 83), levels of CRP (8.4 ± 0.73 mg/mL), IL-1 (177.4 ± 21.3 pg/mL), IL-2 (83.7 ± 11.5 pg/mL), IL-6 (83.7 ± 11.5 pg/mL) and TNF-α (18.3 ± 5.3 pg/mL) as compared to control group. CMC-AgNPs produced highly effective anti-leishmaniasis activity with the viable Leishmania major counts decreased up to 36.7% within 24 h, and the IC₅₀ was found to be 28.41 μg/mL. The potent DPPH radical scavenging potential was also observed for CMC-AgNPs with the IC₅₀ value of 112 μg/mL. Furthermore, the cytotoxicity was assessed using HeLa cell lines with the LC₅₀ of 108.2 μg/mL.

Conclusion

The current findings demonstrate positive attributes of CMC fabricated AgNPs as a promising antibacterial, anti-inflammatory, anti-leishmaniasis, and antioxidant agent with low cytotoxic potential.

Ionic liquid-based antimicrobial materials for water treatment, air filtration, food packaging and anticorrosion coatings

Efforts to widen the scope of ionic liquids applications across diverse research areas have flourished in the last two decades with developments in understanding and tailoring their physical, chemical, and biological properties. The promising applications of ionic liquids-based materials as antimicrobial systems is due to their ability and flexibility to be tailored in varying sizes, morphologies, and surface charges. Ionic liquids are also considered as greener materials. Common methods for the preparation of ionic liquid-based materials include crosslinking, loading, grafting, and combination of ionic liquids with other polymeric materials. Recent research focuses on the tuning of the biological properties to design novel ionic liquids-based antimicrobial materials. Here, the properties, synthesis and applications of ionic liquids and ionic liquids-based materials are reviewed with focus on antimicrobial activities applied to water treatment, air filtration, food packaging, and anticorrosion.

Biomimetic structure of chitosan reinforced epoxy natural rubber with self-healed, recyclable and antimicrobial ability

Inspired by biomaterials with hard and soft structures, we reported a type of self-healed, recyclable and antimicrobial elastomers material (ECTS) which exhibited both strong mechanical strength and high toughness. ECTS was designed by furfuryl amine modified epoxy natural rubber (ENR-FA) and furaldehyde modified chitosan (CTS-FUR) through Diels-Alder (D-A) reaction. The dynamic loading capacity of the chitosan skeleton, the stress ductility of the matrix and the dynamic cross-linking between the hard and soft components gave the elastomer excellent mechanical strength, toughness and self-healing ability. The tensile strength and the elongation at break could reach up to 7.55 MPa and 487%, respectively. In addition, due to the reversibility of the covalent bond between chitosan framework and rubber matrix, the crosslinking network destroyed by external force could be reestablished under high temperature stimulation. The mechanical properties of the sample could be restored to more than 90% of the original sample, whether it was complete fracture, cyclic damage or recyclable. ECTS exhibited excellent antibacterial activity against both gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa), with antibacterial efficiency more than 99%. So, ECTS might has a promising application prospect in medical materials, intelligent devices, 4D-printing, etc.

Bioactive Carboxymethyl Starch-Based Hydrogels Decorated with CuO Nanoparticles: Antioxidant and Antimicrobial Properties and Accelerated Wound Healing In Vivo

In this study, nanocomposite hydrogels composed of sodium carboxymethylated starch (CMS)-containing CuO nanoparticles (CMS@CuO) were synthesized and used as experimental wound healing materials. The hydrogels were fabricated by a solution-casting technique using citric acid as a crosslinking agent. They were characterized by Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA) to evaluate their physicochemical properties. In addition, swelling, antibacterial activities, antioxidant activities, cytotoxicity, and in vivo wound healing were investigated to evaluate the wound healing potential of the CMS@CuO nanocomposite hydrogels. Growth inhibition of the Gram-positive and Gram-negative pathogens, antioxidant activity, and swelling were observed in the CMS@CuO nanocomposite hydrogels containing 2 wt.% and 4 wt.% CuO nanoparticles. The hydrogel containing 2 wt.% CuO nanoparticles displayed low toxicity to human fibroblasts and exhibited good biocompatibility. Wounds created in rats and treated with the CMS@2%CuO nanocomposite hydrogel healed within 13 days, whereas wounds were still present when treated for the same time-period with CMS only. The impact of antibacterial and antioxidant activities on accelerating wound healing could be ascribed to the antibacterial and antioxidant activities of the nanocomposite hydrogel. Incorporation of CuO nanoparticles in the hydrogel improved its antibacterial properties, antioxidant activity, and degree of swelling. The present nanocomposite hydrogel has the potential to be used clinically as a novel wound healing material.

Preparation and Characterization of Biodegradable Composited Films Based on Potato Starch/Glycerol/Gelatin

The use of plastics is resisted worldwide. Therefore, finding alternatives to plastic packaging products is an urgent issue. This work was dedicated to the preparation of biodegradable composited films with potato starch, glycerol, and gelatin. The formulation of the biodegradable film was first optimized via response surface methodology combined with the multi-index comprehensive evaluation method that considered physical properties (thickness, water solution (WS), tensile strength (TS) and elongation at break (E%)) and barrier property (light transmittance (T%)). Results indicated that the optimal conditions were 2.5% starch, 2.0% glycerol, and 1.5% gelatin (based on water). The optimized film presented excellent properties with TS of 4.47 MPa, E% of 109.91%, WS of 43.64%, and T% of 41.21% at 500 nm, and the comprehensive evaluation score of the composite film was 28.68. Moreover, a model verification experiment was further conducted, which proved that the predicted value highly matched experimental values, indicting the credibility and accuracy of the model. The resulting films were further characterized on the basis of rheological measurements, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The rheological measurements proved that the film-forming solution exhibited low shear viscosity and non-Newtonian fluid behavior. FTIR and SEM revealed excellent compatibility among starch, glycerol, and gelatin. Hence, the resulting optimized film may be expected to provide theoretical basis and technical support for the food packing industry.

Pectin-Based Films with Cocoa Bean Shell Waste Extract and ZnO/Zn-NPs with Enhanced Oxygen Barrier, Ultraviolet Screen and Photocatalytic Properties

In this work, pectin-based active films with a cocoa bean shell extract, obtained after waste valorisation of residues coming from the chocolate production process, and zinc oxide/zinc nanoparticles (ZnO/Zn-NPs) at different concentrations, were obtained by casting. The effect of the active additive incorporation on the thermal, barrier, structural, morphological and optical properties was investigated. Moreover, the photocatalytic properties of the obtained films based on the decomposition of methylene blue (MB) in aqueous solution at room temperature were also studied. A significant increase in thermal and oxidative stability was obtained with the incorporation of 3 wt% of ZnO/Zn-NPs compared to the control film. The addition of 5 wt% cocoa bean shell extract to pectin significantly affected the oxygen barrier properties due to a plasticizing effect. In contrast, the addition of ZnO/Zn-NPs at 1 wt% to pectin caused a decrease in oxygen transmission rate per film thickness (OTR.e) values of approximately 50% compared to the control film, resulting in an enhanced protection against oxidation for food preservation. The optical properties were highly influenced by the incorporation of the natural extract but this effect was mitigated when nanoparticles were also incorporated into pectin-based films. The addition of the extract and nanoparticles resulted in a clear improvement (by 98%) in UV barrier properties, which could be important for packaged food sensitive to UV radiation. Finally, the photocatalytic activity of the developed films containing nanoparticles was demonstrated, showing photodegradation efficiency values of nearly 90% after 60 min at 3 wt% of ZnO/Zn-NPs loading. In conclusion, the obtained pectin-based bionanocomposites with cocoa bean shell waste extract and zinc oxide/zinc nanoparticles showed great potential to be used as active packaging for food preservation.

Advances in biogenically synthesized shaped metal- and carbon-based nanoarchitectures and their medicinal applications

Non-spherical metal-based and carbon-based nanostructures have found applications in every facet of scientific endeavors, including engineering and biomedical fields. These nanostructures attract attention because of their biocompatibility and negligible cytotoxicity. Chemical and physical methods have been used for synthesizing earlier generations of metal-based and carbon-based nanostructures with variable architectures, including nanorods, nanowires, nanodots and nanosheets. However, these synthesis strategies utilize organic passivators which are toxic to the environment and the human body. Biogenic synthesis of nanoparticles is becoming increasing popular because of the necessity to develop eco-friendly and non-toxic strategies. Nanoparticles synthesized by natural compounds have immense potential in the biomedical arena. The present review focuses on plant-mediated synthesis of metal-based and carbon-based non-spherical nanoarchitectures and the role of green synthesis in improving their activities for biomedical applications.