The evolving threat of antibiotic resistance development in pathogenic bacteria necessitates the continued cultivation of new technologies and agents to mitigate associated negative health impacts globally. It is no surprise that infection prevention and control are cited by the Centers for Disease Control and Prevention (CDC) as two routes for combating this dangerous trend. One technology that has gained great research interest is antimicrobial photodynamic inactivation of bacteria, or APDI. This technique permits controllable activation of antimicrobial effects by combining specific light excitation with the photodynamic properties of a photosensitizer; when activated, the photosensitizer generates reactive oxygen species (ROS) from molecular oxygen via either a type I (electron transfer) or type II (energy transfer) pathway. These species subsequently inflict oxidative damage on nearby bacteria, resulting in suppressed growth and cell death. To date, small molecule photosensitizers have been developed, yet the scalability of these as widespread sterilization agents is limited due to complex and costly synthetic procedures. Herein we report the use of brominated carbon nanodots (BrCND) as new photosensitizers for APDI. These combustion byproducts are easily and inexpensively collected; incorporation of bromine into the nanodot permits photosensitization effects that are not inherent to the carbon nanodot structure alone—a consequence of triplet character gained by the heavy atom effect. BrCND demonstrate both type I and type II photosensitization under UV-A irradiation, and furthermore are shown to have significant antimicrobial effects against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus and Listeria monocytogenes as well. A mechanism of “dark” toxicity is additionally reported; the pH-triggered release of reactive nitrogen species is detected from a carbon nanodot structure for the first time. The results described present the BrCND structure as a competitive new antimicrobial agent for controllable sterilization of bacteria.

中文翻译：

---

抗菌碳纳米点：溴化碳纳米点对细菌的光动力灭活和暗抗菌作用

病原菌抗生素耐药性的威胁不断演变，需要继续培育新技术和药剂，以减轻全球相关的负面健康影响。毫不奇怪，美国疾病控制与预防中心 (CDC) 将感染预防和控制列为对抗这一危险趋势的两条途径。一项引起广泛研究兴趣的技术是细菌光动力抗菌灭活（APDI）。该技术通过将特定的光激发与光敏剂的光动力学特性相结合，可以可控地激活抗菌作用；激活后，光敏剂通过I 型（电子转移）或 II 型（能量转移）途径从分子氧产生活性氧 (ROS) 。这些物种随后对附近的细菌造成氧化损伤，导致生长受到抑制和细胞死亡。迄今为止，小分子光敏剂已经被开发出来，但由于合成过程复杂且昂贵，这些作为广泛灭菌剂的可扩展性受到限制。在此，我们报告了使用溴化碳纳米点（BrCND）作为 APDI 的新型光敏剂。这些燃烧副产品可以轻松且廉价地收集；将溴掺入纳米点可以产生碳纳米点结构所不具备的光敏效应——这是重原子效应获得的三重态特征的结果。BrCND 在 UV-A 照射下表现出 I 型和 II 型光敏性，并且对革兰氏阴性大肠杆菌、革兰氏阳性金黄色葡萄球菌和单核细胞增生李斯特氏菌均具有显着的抗菌作用。另外还报道了“暗”毒性的机制；首次从碳纳米点结构中检测到 pH 值触发的活性氮物质的释放。所描述的结果表明 BrCND 结构作为一种有竞争力的新型抗菌剂，可用于细菌的可控灭菌。