Green synthesis of cellulose nanocrystal/ZnO bio-nanocomposites exerting antibacterial activity and downregulating virulence toxigenic genes of food-poisoning bacteria

Abstract

Recently, cellulose nanocrystals (CNs) have attracted wide attention owing to their superior properties compared to their bulk materials. For example, they represent an outstanding model for fabricating green metallic/metal oxide nanoparticles (NPs). In this study, two CNs (carboxylated CNs and sulfated CNs) extracted from agro-wastes of palm sheath fibers were used as templates for the facile and green synthesis of ZnO NPs by employing the sono-co-precipitation method. The obtained nanomaterials were characterized using TEM, EDX, UV–visible, DLS, FT-IR, and XRD analysis. As a result, the size and concentration of synthesized ZnO NPs were inversely proportional to one another and were affected by the CNs utilized and the reaction temperature used. Contagious diseases incited by multifarious toxigenic bacteria present severe threats to human health. The fabricated bio-nanocomposites were evaluated in terms of their antimicrobial efficacy by agar well diffusion method and broth microdilution assay, showing that CN–ZnO bio-nanocomposites were effective against the tested Gram-negative (Escherichia coli and Salmonella) and Gram-positive (Listeria monocytogenes and Staphylococcus aureus) bacteria. The influence of the subinhibitory concentrations of these suspensions on the expression of the most critical virulence toxin genes of the tested strains was effective. Significant downregulation levels were observed through toxigenic operons to both fabricated CN–ZnO bio-nanocomposites with a fold change ranging from 0.004 to 0.510, revealing a decline in the capacity and virulence of microorganisms to pose infections. Therefore, these newly fabricated CNS–ZnO bio-nanocomposites could be employed rationally in food systems as a novel preservative to inhibit microbial growth and repress the synthesis of exotoxins.

Boosting brackish water treatment via integration of mesoporous γ-Al2O3NPs with thin-film nanofiltration membranes

“…In addition, both the octahedral and tetrahedral coordination of the γ-phase of Al 2 O 3 NPs can be inferred from the shoulder that appeared at 758 cm −1 , the line at 950 cm −1 for Al IV , and the peaks at 563, 622, and 758 cm −1 assigned to Al VI 41 . However, the observation of three absorption peaks at 1640, 1540, and 1416 cm −1 can be an indication of the potential covalently bonded carboxylate groups (comprise bridging carboxylates) covering the Al 2 O 3 NPs surface 42 . Accordingly, after calcination at a temperature of 800 °C, carboxylate groups' remains, and this consequently forms organic substituted Al 2 O 3 NPs.…”

Nanotechnological approaches for management of soil-borne plant pathogens

“…These compounds are considered as environment friendly as these are biodegradable and are abundantly found in nature. Dawwam et al (2022) green synthesized cellulose nanocrystals (CNs) using agrowastes obtained from palm sheath fibers and ZnONPs were synthesized using sono-co-precipitation method. The CNS-ZnO bionanocomposite were evaluated for antibacterial activity against gram negative (Escherichia coli and Salmonella) and Gram-positive (Listeria monocytogenes and Staphylococcus aureus) bacteria which possess ability to persist in soil.…”

Biogenic silver-doped mesoporous silica nanoparticles for multifunctional eco-designed textile printing

“…From Fig. 3b, the main diffraction peaks at Bragg angles (2θ°) of 15.6° and 22.14° of the RH are attributed to the diffraction patterns from the crystal structure of the cellulose content [55]. On the other hand, the broad peak at Bragg angles (2θ°) of ca 22° in the diffraction profiles of the extracted SiO 2 NPs is characteristic of the amorphous phase of mesoporous SiO 2 NPs [3,10].…”