Centre for Materials for Electronics Technology, Panchawati, Pashan Road, Pune 411008, India.
Nanotechnology. 2020 Nov 27;31(48):485705. doi: 10.1088/1361-6528/ab9da5.
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 and Gram negative bacteria like Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas 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 A. fumigatus. The highest value of MIC (75 µg ml) for Ag-Cu 0.1M core shell nanostructures (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 Cu-Ag 0.1M core shell nanostructures (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 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.
采用简单的化学还原法，在室温下于聚乙烯醇（PVA）基质内合成了 Cu-Ag 和 Ag-Cu 核壳纳米结构。通过使用水合肼（HH）作为还原剂，以不同浓度（即 0.1 和 0.01 M）的两种不同金属离子等摩尔比进行连续还原，合成了核壳纳米结构。通过不同的表征技术进一步对核壳纳米结构进行了表征。紫外-可见光谱显示出各自的能带位置发生了位移，表明形成了核壳纳米结构，这通过场发射透射电子显微镜-高角环形暗场元素映射进一步得到证实。通过进行 MIC 和 MBC/MFC 研究，观察了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烟曲霉）的影响。结果表明，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均具有有效的抗菌作用，而 Ag-Cu 核壳纳米结构对一种特定的真菌烟曲霉更为有效。Ag-Cu 0.1M 核壳纳米结构（D1）对金黄色葡萄球菌和大肠杆菌的 MIC 值最高（75 µg ml），而对铜绿假单胞菌的 MIC 值最低（20 µg ml）。而对于 Cu-Ag 0.1M 核壳纳米结构（E1），对金黄色葡萄球菌和铜绿假单胞菌的 MIC 值最高（100 µg ml），而对烟曲霉的 MIC 值最低（15 µg ml）。此外，未处理和核壳纳米颗粒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 Cu-Ag 核壳纳米结构可以成功破坏真菌烟曲霉和细菌铜绿假单胞菌的细胞壁。因此，本研究得出结论，Cu-Ag 和 Ag-Cu 核壳纳米结构破坏微生物的细胞结构并抑制其生长。因此，本研究中的 Cu-Ag 和 Ag-Cu 核壳纳米结构分别对细菌和真菌表现出良好的抗菌作用。
