A simple chemical reduction method was employed to synthesize Cu-Ag and Ag-Cu core-shell nanostructures inside polyvinyl alcohol (PVA) matrix at room temperature. The core-shell nanostructures have been synthesized by varying the two different concentrations (i.e. 0.1 and 0.01 M) of the respective metal ions in equimolar ratios using successive reduction with hydrazine hydrate (HH) as a reducing agent. The core-shell nanostructures have been further characterized by different characterization techniques. The UV-visible spectroscopy exhibit the respective shift in the band positions suggesting the formation of core-shell nanostructures, which was further confirmed by field emission transmission electron microscopy-high-angle-annular dark field elemental mapping. The effect of metal ion concentration of the core-shell nanostructure on various gram positive & gram negative bacteria like E. coli, S. aureus, K. pneumoniae, P. aeruginosa and one fungal species Aspergillus fumigatus was observed by performing MIC and MBC/MFC study. Cu-Ag core-shell nanostructures were found to be effective antibacterial agent against all tested Gram-positive and Gram-negative bacteria, whereas Ag-Cu core-shell nanostructures were more efficient against a particular fungal species known as Aspergillus fumigatus. The highest value of MIC (75 µg/mL) for D1 was noted against S. aureus and E. coli whereas the lowest value (20 µg/mL) was observed with P. aeruginosa. While in case of E1 the highest value of MIC (100 µg/mL) was noted against S. aureus and P. aeruginosa whereas the lowest value (15 µg/mL) was observed with A. fumigatus. Also, field effect scanning electron microscope (FESEM) images of untreated and core-shell nanoparticles treated micro-organisms showed that 0.1 M Ag-Cu and 0.1 M concentration Cu-Ag core-shell nanostructure can successfully break the cell wall of the fungi A. fumigatus and bacteria P. aeruginosa respectively. Thus the present study concludes that, Cu-Ag & Ag-Cu core-shell nanostructures damage the cell structure of micro-organisms and inhibits their growth. Hence, the present Cu-Ag & Ag-Cu core-shell nanostructure acts as good antimicrobial agent against the bacteria and fungi respectively.

中文翻译：

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原位合成 PVA 的 Ag-Cu 和 Cu-Ag 核壳纳米结构的选择性抗真菌和抗菌活性。

在室温下，采用简单的化学还原方法在聚乙烯醇 (PVA) 基质内合成 Cu-Ag 和 Ag-Cu 核壳纳米结构。核壳纳米结构是通过使用水合肼 (HH) 作为还原剂连续还原以等摩尔比改变两种不同浓度（即 0.1 和 0.01 M）的相应金属离子来合成的。核壳纳米结构已通过不同的表征技术进一步表征。紫外-可见光谱表现出带位置的相应偏移，表明核壳纳米结构的形成，这通过场发射透射电子显微镜-高角度-环形暗场元素映射进一步证实。核壳纳米结构的金属离子浓度对各种革兰氏阳性和革兰氏阴性细菌如大肠杆菌、金黄色葡萄球菌、肺炎克雷伯菌、铜绿假单胞菌和一种真菌种类烟曲霉的影响通过进行 MIC 和 MBC/ MFC 研究。发现 Cu-Ag 核壳纳米结构对所有测试的革兰氏阳性和革兰氏阴性细菌都是有效的抗菌剂，而 Ag-Cu 核壳纳米结构对称为烟曲霉的特定真菌物种更有效。D1 的最高 MIC 值 (75 µg/mL) 是针对金黄色葡萄球菌和大肠杆菌，而最低值 (20 µg/mL) 是针对铜绿假单胞菌。而在 E1 的情况下，针对金黄色葡萄球菌和铜绿假单胞菌的 MIC 最高值 (100 µg/mL) 而最低值 (15 µg/mL) 在 A. 熏烟。此外，未经处理和核壳纳米粒子处理的微生物的场效应扫描电子显微镜 (FESEM) 图像表明，0.1 M Ag-Cu 和 0.1 M 浓度的 Cu-Ag 核壳纳米结构可以成功破坏真菌 A 的细胞壁. fumigatus 和细菌 P. aeruginosa 分别。因此，本研究得出结论，Cu-Ag 和 Ag-Cu 核壳纳米结构会破坏微生物的细胞结构并抑制其生长。因此，本发明的 Cu-Ag 和 Ag-Cu 核壳纳米结构分别作为对细菌和真菌的良好抗菌剂。1 M浓度的Cu-Ag核壳纳米结构可以分别成功地破坏真菌A. fumigatus和细菌P. aeruginosa的细胞壁。因此，本研究得出结论，Cu-Ag 和 Ag-Cu 核壳纳米结构会破坏微生物的细胞结构并抑制其生长。因此，本发明的 Cu-Ag 和 Ag-Cu 核壳纳米结构分别作为对细菌和真菌的良好抗菌剂。1 M浓度的Cu-Ag核壳纳米结构可以分别成功地破坏真菌A. fumigatus和细菌P. aeruginosa的细胞壁。因此，本研究得出结论，Cu-Ag 和 Ag-Cu 核壳纳米结构会破坏微生物的细胞结构并抑制其生长。因此，本发明的 Cu-Ag 和 Ag-Cu 核壳纳米结构分别作为对细菌和真菌的良好抗菌剂。