纳米银的合成及其抗菌机制研究

发布时间：2018-05-25 03:20

本文选题：纳米银 + 抑菌　；参考：《苏州大学》2015年硕士论文

【摘要】：纳米银是以纳米技术为基础研制而成的新型抗菌产品,比Ag+具有更稳定的物理化学特性,由于小尺寸效应、量子效应和具有极大的比表面积,因而具有传统无机抗菌剂无法比拟的抗菌效果,使银所具有的强效消毒杀菌功能更是有了质的飞跃,且效力持久、安全性高,不易产生耐药性。生物合成纳米银,具有安全性高、绿色环保、成本低廉等特点,在绿色合成纳米银领域有着广阔的应用前景。本文分别采用化学方法和生物方法合成纳米银,研究其抑菌活性,并探讨了抑菌机理。化学合成纳米银利用抗坏血酸作为还原剂,通过二氧化硅的包裹,成功的得到平均粒径为92.9 nm的核壳型银-二氧化硅纳米粒(Ag-Si O2 NPs)。该纳米粒子可抑制人类病原菌白色念珠菌以及植物病原菌香石竹镰刀菌的生长。通过常量肉汤稀释法,确定了Ag-Si O2 NPs对白色念珠菌的IC50为2μg/ml。通过杯碟法测定对植物病原菌香石竹镰刀菌的抑制,最低抑菌浓度(MIC)为4μg/ml。本实验首次利用红豆杉细胞的提取液作为原料,绿色合成了粒径为3-5 nm均一度良好的纳米银,p H=10,反应时间60 min为反应最佳条件。抑菌实验表明,用红豆杉合成的纳米银对人类病原菌有较强的抑制作用,尤其是革兰氏阳性菌,对于金黄色葡萄球菌(Staphylococcus aureus)和枯草芽孢杆菌(Bacillus subtilis)的最低抑菌浓度低至1μg/ml;对于革兰氏阴性菌大肠埃希菌(Escherichia coil)的最低抑菌浓度为8μg/ml,对乙型副伤寒沙门菌(Salmonella paratyphi B)的最低抑菌浓度为4μg/ml。最后我们探讨了纳米银对人类病原菌白色念珠菌(Candida albicans)、植物病原菌香石竹镰刀菌(Fusarium oxysporum)的抑菌机制,为纳米银抑菌应用供理论依据。研究结果表明:(1)Ag-Si O2 NPs独特的核壳型结构可以缓慢释放银离子,当引入半胱氨酸螯合培养基中释放的Ag+后,依然有较强的抑菌能力,说明Ag-Si O2 NPs的抑菌作用是Ag+和纳米级别粒子共同作用的结果。(2)进一步研究了Ag-Si O2 NPs对成膜白色念珠菌的抑制能力。结果表明,Ag-Si O2 NPs不仅对生物膜形成初期有抑制作用,对成熟期的菌膜仍然有良好的抑菌效果,说明Ag-Si O2 NPs可以不受胞外基质的阻碍,抑制生物膜的形成和发展。(3)在Ag-Si O2 NPs作用下,镰刀菌菌丝体的生长呈现异常状态,且无法正常分生孢子,说明Ag-Si O2纳米粒可能会促使镰刀菌畸变,使其无法正常生长,繁殖,失去侵染植物能力。(4)通过流式细胞仪检测发现,抑菌过程中有活性氧(ROS)的产生,同时我们测得线粒体膜电位△Ψm明显下降,呈一定的时间剂量依赖关系。Ag-Si O2 NPs处理镰刀菌后,细胞内抗氧化酶如过氧化氢酶、总超氧化物歧化酶、过氧化物酶的活力呈现上升以后再下降的趋势,结果说明:纳米银可能通过刺激菌体产生ROS,导致菌体氧化还原态势显著变化,诱导菌体线粒体膜电位△Ψm下降,从而造成菌体的死亡。本论文探讨了纳米银合成的化学方法和生物方法,我们首次报道了利用红豆杉细胞绿色合成纳米银的方法。通过研究纳米银的抑菌机制,揭示了纳米银诱导菌体活性氧产生,以及对菌体生物膜形成的破坏、孢子萌发和菌体生长的抑制,为纳米银抗菌研究提供了新型合成方法和较深入的抗菌机制。
[Abstract]:Nano silver is a new type of antibacterial product developed on the basis of nanotechnology. It has more stable physical and chemical properties than Ag+. Because of its small size effect, quantum effect and great specific surface area, it has the antiseptic effect incomparable with the traditional inorganic antiseptic, and makes the sterilizing and sterilizing function of silver more qualitative. The biosynthesis of nano silver, which has the characteristics of high safety, green environmental protection, low cost and so on, has a broad application prospect in the field of green synthesis of nano silver. In this paper, the antibacterial activity of nano silver was combined with chemical methods and biological methods, and the antibacterial mechanism was studied and the antibacterial mechanism was discussed. The chemical synthesis of silver nanoparticles using ascorbic acid as a reducing agent, through the inclusion of silica, has successfully obtained a nucleated shell type silver silica nanoparticles (Ag-Si O2 NPs) with an average particle size of 92.9 nm. This nanoparticle can inhibit the growth of Candida albicans and plant pathogenic fungus Fusarium oxycariensis. Ag-Si O2 NPs was used to determine the IC50 of Candida albicans to 2 mu g/ml. by cup disc method. The minimum inhibitory concentration (MIC) was 4 u g/ml.. The extraction solution of Taxus cells was used for the first time as raw material. The green synthesis of nano silver with a good uniformity of diameter of 3-5 nm, P H=10, reaction Time 60 min was the best reaction condition. Bacteriostasis experiment showed that nanoscale silver synthesized by Taxus had strong inhibitory effect on human pathogenic bacteria, especially Gram-positive bacteria, the minimum inhibitory concentration for Staphylococcus aureus (Staphylococcus aureus) and Bacillus subtilis (Bacillus subtilis) was low to 1 u g/ml; The minimum inhibitory concentration of Escherichia coli (Escherichia coil) was 8 u g/ml, and the minimum inhibitory concentration for Salmonella paratyphi B was 4 u g/ml.. Finally, we explored the Bacteriostasis of nanoscale silver to human pathogen Candida albicans (Candida albicans), and the pathogen of plant pathogen (Fusarium oxysporum). The mechanism is the theoretical basis for the antibacterial application of nano silver. The results show that: (1) the unique nuclear shell structure of Ag-Si O2 NPs can release silver ions slowly. After introducing the Ag+ released in the cysteine chelate medium, it still has strong bacteriostasis. It shows that the Bacteriostasis of Ag-Si O2 NPs is the joint of Ag+ and nanoscale particles. Fruit. (2) further study the inhibition ability of Ag-Si O2 NPs on the membrane of Candida albicans. The results show that Ag-Si O2 NPs not only has inhibitory effect on the early stage of biofilm formation, but also has good bacteriostasis effect on the membrane of mature period, indicating that Ag-Si O2 NPs can not be hindered by extracellular matrix and inhibits the formation and development of biofilm. (3) Ag-Si O. Under the action of 2 NPs, the growth of Fusarium mycelium is abnormal and can not be normal conidia. It shows that Ag-Si O2 nanoparticles may induce the aberration of Fusarium, so that it can not grow normally, reproduce and lose the ability to infect plants. (4) it was found by flow cytometry that the production of active oxygen (ROS) in the process of bacteriostasis, and we have measured it. The mitochondrial membrane potential delta m decreased obviously, and the activity of intracellular antioxidant enzymes such as catalase, total superoxide dismutase and peroxidase decreased after a certain time dose dependence of.Ag-Si O2 NPs, and the results showed that nano silver may produce ROS by stimulating the mycelium and lead to the mycelium. In this paper, the chemical methods and biological methods for the synthesis of nano silver were discussed. We first reported the method of using the green synthesis of silver in the Taxus cells. The antibacterial mechanism of nano silver was studied and the nano silver lure was revealed. The production of the active oxygen of the mycelium, the destruction of the biofilm formation, the germination of the spores and the inhibition of the growth of the mycelium, provide a new synthesis method and a more thorough antibacterial mechanism for the antibacterial study of nano silver.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

【引证文献】