Ultrasmall silver nanoclusters (Ag NCs) with rich surface chemistry and good biocompatibility are promising in antibacterial application, however, further development of Ag NCs for practical settings has been constrained by their relatively weak antibacterial activity. Using the nutritionally-rich medium for bacteria (e.g., Luria-Bertani (LB) medium) to coat active Ag NCs could further improve their antibacterial activity. Here, we provide a delicate design of a highly efficient Ag NCs@ELB antibacterial agent (ELB denotes the extract of LB medium) by anchoring Ag NCs inside the ELB species via light irradiation. The as-designed Ag NCs with bacterium-favored nutrients on the surface can be easily swallowed by the bacteria, boosting the production of the intracellular reactive oxygen species (ROS, about 2-fold of that in the pristine Ag NCs). Subsequently, a higher concentration of ROS generated in Ag NCs@ELB leads to enhanced antibacterial activity, and enables to reduce the colony forming units (CFU) of both gram-positive and gram-negative bacteria with 3–4 orders of magnitude less than that treated with the pristine Ag NCs. In addition, the Ag NCs@ELB also shows good biocompatibility. This study suggests that surface engineering of active species (e.g., Ag NCs) with nutritionally-rich medium of the bacteria is an efficient way to improve their antibacterial activity.

中文翻译：

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通过光辐照将超小型Ag纳米团簇嵌入Luria-Bertani提取物中以增强抗菌活性

具有丰富的表面化学特性和良好的生物相容性的超小型银纳米簇（Ag NCs）在抗菌应用中很有前景，但是，由于其相对较弱的抗菌活性，实际应用中的Ag NCs的进一步开发受到了限制。使用营养丰富的细菌培养基（例如Luria-Bertani（LB）培养基）覆盖活性Ag NCs可以进一步提高其抗菌活性。在这里，我们通过光照射将Ag NCs锚定在ELB物种内部，从而提供了高效的Ag NCs @ ELB抗菌剂（ELB表示LB培养基的提取物）的精细设计。设计好的表面上具有细菌营养成分的Ag NCs可以很容易地被细菌吞噬，从而提高了细胞内活性氧的含量（ROS，约为原始Ag NCs的2倍）。随后，较高浓度的Ag NCs @ ELB中产生的ROS会增强抗菌活性，并能减少革兰氏阳性菌和革兰氏阴性菌的菌落形成单位（CFU），其含量要比后者低3-4个数量级。用原始的Ag NCs处理。另外，Ag NCs @ ELB也显示出良好的生物相容性。这项研究表明，利用细菌的营养丰富的培养基对活性物种（例如Ag NCs）进行表面工程改造是提高其抗菌活性的有效方法。Ag NCs @ ELB也显示出良好的生物相容性。这项研究表明，利用细菌的营养丰富的培养基对活性物种（例如Ag NCs）进行表面工程改造是提高其抗菌活性的有效方法。Ag NCs @ ELB也显示出良好的生物相容性。这项研究表明，利用细菌的营养丰富的培养基对活性物种（例如Ag NCs）进行表面工程改造是提高其抗菌活性的有效方法。