Ag QDs对耐药沙门氏菌的细胞壁的损伤研究

The Effect of Ag Quantum Dots on Cell Wall of Drug-Resistant Salmonella spp.

摘要: 因有机抗生素滥用使细菌产生耐药，所以探寻高效且不产生耐药的抑菌剂已成为21世纪的最大挑战之一，无机抑菌剂纳米Ag对细菌甚至耐药菌都具有强的抑制性能，但纳米银的抑制活性和粒径相关，粒径越小，表面能越高，抑菌活性越强，但粒径越小越易团聚从而降低其性能。为此，本研究利用Ag可与供电子基团N原子的强配位性，将制备的Ag量子点(Ag QD)负载在聚多巴胺表面合成超小粒径的Ag QDs复合材料，通过透射电镜(TEM)，X射线衍射(XRD)，X射线光电子能谱分析(XPS)等对其形貌和晶型进行分析，以耐药沙门氏菌为模式菌研究Ag QDs的抑菌活性，并探究其抑菌机制。结果表明，相比单独的纳米Ag，将~3 nm Ag量子点分散在聚多巴胺表面可提高其稳定性，抑菌性能研究中显示，制备的Ag QDs在30 min内，浓度为300 μg/mL时对耐药沙门氏菌的抑菌效率为99%以上，且可高效的损害沙门氏菌的细胞壁，诱使细菌内部的K⁺，Ca²⁺和Mg²⁺离子泄露而使细菌产生不可逆死亡。因此，Ag QDs复合材料高效的抑菌活性有望应用于抑菌敷料等医疗领域。

Abstract: Due to the abuse of organic antibiotics, bacteria are resistant to antibiotics, so it has become one of the biggest challenges in the 21st century to explore efficient and non-resistant bacteriostatic agents. Inorganic bacteriostatic agent nano-Ag has strong inhibitory properties against bacteria and even drug-resistant bacteria, but the inhibitory activity of nano-Ag is related to particle size. The smaller the particle size, the higher the surface energy, the stronger the bacteriostatic activity, but the smaller the particle size, the easier it is to agglomerate and reduce its performance. Therefore, in this study, the prepared Ag quantum dots (Ag QDs) were loaded on the surface of polydopamine to synthesize Ag QDs composites with ultra-small particle size by using the strong coordination of Ag with the electron-donating group N atom. The morphology and crystal form were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), etc. The antibacterial activity of Ag QDs was studied by using drug-resistant Salmonella as a model bacterium, and its antibacterial mechanism was explored. The results showed that the dispersion of ~3 nm Ag quantum dots on the surface of polydopamine could improve its stability compared with single nano-Ag. The antibacterial performance study showed that the prepared Ag QDs had an antibacterial efficiency of more than 99% against drug-resistant Salmonella within 30 min at a concentration of 300 μg/mL, and could efficiently damage the cell wall of Salmonella, inducing the leakage of K⁺, Ca²⁺ and Mg²⁺ ions inside the bacteria and causing irreversible death of the bacteria. Therefore, the efficient antibacterial activity of Ag QDs composites is expected to be applied in medical fields such as antibacterial dressings.