“Luminescent-off/on” sensing mechanism of antibiotic-capped gold nanoclusters to phosphate-containing metabolites and its antibacterial characteristics

Gold-based nanomaterials have broad applications in analysis, catalysts, antibiotics, and tissue imaging. In this article, the water-soluble, monodispersed gold nanoclusters (AuNC) have been synthesized using vancomycin (van) as a temple and reducing agent. Van-bound gold nanoclusters (AuNC@Van) exhibit a high tendency to undergo fluorescence quenching in the presence of Fe2+/H2O2. The fluorescence quenching mechanism has been investigated in detail. We find that the luminescence of AuNC@Van is quenched when chelating with iron ions, which are the main product of the Fenton reaction. In successive experiments, we found that the luminescence of the gold nanoclusters can be switched on in the presence of phosphate-containing molecules and some antioxidants, which suggests the possibility of using the AuNC@Van − Fe2+/H2O2 complexes as selective luminescent switches for phosphate-containing metabolites and antioxidants, particularly adenosine triphosphate. The total assay duration can be completed within 1 min. Our method shows great accuracy when it is used to detect the total phosphate-containing metabolite capacity in a human plasma sample. The prepared AuNC@Van had low toxicity to the HepG2 cell in the tested concentration range. In addition, for the first time, AuNC@Van was used in an antimicrobial application, and AuNC@Van has good antimicrobial activities towards both Gram-negative and Gram-positive bacteria.

金基纳米材料在分析、催化、抗菌和组织成像等方面具有广泛应用。在本文中，以万古霉素（van）为模板和还原剂合成了水溶性、单分散的金纳米团簇（AuNC）。万古霉素结合的金纳米团簇（AuNC@Van）在Fe²⁺/H₂O₂存在的情况下表现出高度的荧光猝灭倾向。对荧光猝灭机制进行了详细研究。我们发现，当与铁离子螯合时，AuNC@Van的发光会被猝灭，铁离子是芬顿反应的主要产物。在后续实验中，我们发现金纳米团簇的发光在含磷酸盐分子和一些抗氧化剂存在的情况下可以被开启，这表明将AuNC@Van - Fe²⁺/H₂O₂复合物用作含磷酸盐代谢物和抗氧化剂（特别是三磷酸腺苷）的选择性发光开关的可能性。整个检测过程可在1分钟内完成。我们的方法在用于检测人血浆样本中含磷酸盐代谢物的总含量时显示出很高的准确性。所制备的AuNC@Van在测试浓度范围内对HepG2细胞毒性较低。此外，AuNC@Van首次被用于抗菌应用，并且对革兰氏阴性菌和革兰氏阳性菌都具有良好的抗菌活性。