Recently, different nanocrystals have been reported to be the alternative, optimistic, and novel antimicrobial agent against the many antibiotic‐resistant bacteria. Here, ligand‐free CdS and Ag‐doped CdS (Ag/CdS) nanocrystals have been synthesized by chemical methods for the study of the antimicrobial activity on Escherichia coli and Staphylococcus aureus by Kirby–Bauer diffusion method to see the effect against Gram‐positive and Gram‐negative bacteria. These prepared nanocrystals have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD). TEM and SEM images confirm the spherical morphology of both the sample and the respective XRD patterns indicate polycrystalline nature having a cubic zinc blende structure. Antibacterial activities have been tested with CdS and Ag/CdS, considering concentrations ranging from 10 to 200 μg/ml. After 24 h of incubation, the zone of inhibition (ZOI) is measured for each concentration, which shows that both the nanocrystals are ineffective against E. coli but much effective against S. aureus at this low concentration range. Furthermore, Ag/CdS nanocrystals have been found to show much more ZOI than CdS. Differences in the antibacterial activity can be due to the presence of different cell wall in E. coli and S. aureus.

中文翻译：

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银掺杂增强合成的无配体硫化镉纳米晶体的抗菌活性

最近，据报道，不同的纳米晶体是针对许多抗生素耐药细菌的替代、乐观和新型抗菌剂。在这里，通过化学方法合成了无配体的 CdS 和掺杂 Ag 的 CdS (Ag/CdS) 纳米晶体，用于通过 Kirby-Bauer 扩散法研究对大肠杆菌和金黄色葡萄球菌的抗菌活性，以观察对革兰氏阳性菌的作用和革兰氏阴性菌。这些制备的纳米晶体已通过透射电子显微镜 (TEM)、扫描电子显微镜 (SEM) 和 X 射线衍射 (XRD) 进行表征。TEM 和 SEM 图像证实了样品的球形形态，相应的 XRD 图案表明具有立方闪锌矿结构的多晶性质。已用 CdS 和 Ag/CdS 测试了抗菌活性，考虑浓度范围为 10 至 200 μg/ml。孵育 24 小时后，测量每个浓度的抑菌圈 (ZOI)，这表明两种纳米晶体对大肠杆菌均无效，但在此低浓度范围内对金黄色葡萄球菌有效。此外，已发现 Ag/CdS 纳米晶体比 CdS 显示出更多的 ZOI。抗菌活性的差异可能是由于大肠杆菌和金黄色葡萄球菌中存在不同的细胞壁。