Botany and Microbiology Department, Faculty of Science, Benha University, Benha, Egypt, P.O. 13518.
Cellulose and Paper Department, National Research Centre, 33 El-Bohouth St. (Former El-Tahrir St.), Dokki, Giza, P.O. 12622, Egypt.
Sci Rep. 2022 Oct 7;12(1):16848. doi: 10.1038/s41598-022-21087-6.
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.
最近，由于其优于块状材料的性能，纤维素纳米晶体（CNs）引起了广泛的关注。例如，它们代表了制造绿色金属/金属氧化物纳米颗粒（NPs）的杰出模型。在这项研究中，两种从棕榈鞘纤维农业废料中提取的 CNs（羧基化 CNs 和硫酸化 CNs）被用作模板，通过超声共沉淀法，通过简单且绿色的方法合成 ZnO NPs。通过 TEM、EDX、UV-可见、DLS、FT-IR 和 XRD 分析对所获得的纳米材料进行了表征。结果表明，合成 ZnO NPs 的尺寸和浓度成反比，并且受到所使用的 CNs 和反应温度的影响。由多种产毒细菌引起的传染病对人类健康构成严重威胁。通过琼脂孔扩散法和肉汤微量稀释法评估了所制备的生物纳米复合材料的抗菌功效，表明 CN-ZnO 生物纳米复合材料对测试的革兰氏阴性（大肠杆菌和沙门氏菌）和革兰氏阳性（李斯特菌和金黄色葡萄球菌）细菌有效。这些悬浮液的亚抑菌浓度对测试菌株的最关键毒力毒素基因的表达具有影响。通过产毒操纵子观察到明显的下调水平，两种制备的 CN-ZnO 生物纳米复合材料的折叠变化范围为 0.004 至 0.510，表明微生物感染能力和毒力下降。因此，这些新制备的 CNS-ZnO 生物纳米复合材料可以合理地用作食品系统中的新型防腐剂，以抑制微生物生长并抑制外毒素的合成。
