不同形态纳米银的制备及其杀菌性能研究

发布时间：2018-06-27 09:04

本文选题：纳米银 + 微波合成法　；参考：《华南理工大学》2014年硕士论文

【摘要】：生活饮用水安全与人体健康息息相关，而细菌超标是造成生活饮用水不安全的首要原因。目前常规饮用水除菌杀菌技术都存在着各自的缺陷，因此，开发饮用水除菌杀菌的新方法、新材料，具有现实意义。纳米银作为一种新型杀菌材料，具有高效、广谱、安全等特性，在饮用水杀菌领域具有潜在应用前景。研究发现纳米银的形貌对其性能有重要影响，然而纳米银形貌与其杀菌性能的关系尚未研究透彻。为此，本论文对纳米银的形貌可控合成、抗菌杀菌性能开展研究，以便为纳米银饮用水杀菌技术的应用提供基础依据，，研究得到以下主要结果和结论：以20mL乙二醇为还原剂，90mg硝酸银为银源，运用微波加热合成法可快速制备银纳米结构。投加氯离子控制合成体系的反应速率，在适当的反应时间内，可选择性合成出不同形貌纳米银。其中，在低NaCl投量水平下（小于0.1mg），获得准球形纳米银颗粒产物；在适中NaCl投量水平下（1mg），产物为以银立方体为主的纳米颗粒；在高NaCl投量水平下（5mg），获得以银纳米线为主的产物。银立方体的最优合成条件为：氯化钠投加量0.5-1mg，反应时间2min；银纳米线的最优合成条件为：氯化钠投加量5mg，反应时间3min30s。用电子显微镜、XRD、UV-Vis、SAED等手段对纳米银形貌、晶体结构的表征结果为，球形纳米银直径为60±15nm，为多晶结构；银立方体的边长为55±10nm，为单晶结构；银纳米线线径60±10nm，线长2-4um，为娈晶结构。三种形态纳米银对大肠杆菌均具有抑菌和杀菌效果，抑菌杀菌效果随纳米银浓度和反应时间的延长而增强。银立方体的杀菌效能最好，球形纳米银次之，银纳米线的杀菌作用最弱。银立方体和球形纳米银对浓度为106CUF/mL的E. coli的最小杀菌浓度分别为75ug/mL和100ug/mL，而银纳米线浓度在0~100ug/mL范围内没有MIC。当纳米银的浓度为50ug/mL时，银立方体可将E. coli的适应期延长超过12h，球形纳米银能延长至9h，而银纳米线仅能延长6h。反应1min，浓度25ug/mL的银立方体和浓度100ug/mL的球形纳米银能完全灭活大肠杆菌，而银纳米线即使当浓度达到100ug/mL时仍不能使细菌完全灭活。纳米银杀菌性能既与其形貌相关，也与其晶面相关。与银纳米颗粒相比，银纳米线限于其一维纳米结构，长径比大，与细菌的接触相对不充分，导致其较弱的杀菌性能；银立方体具有较高反应活性的{100}晶面，杀菌效果较好，而球形纳米银暴露的{111}晶面相对稳定，因而杀菌效果相对较差。三种形态纳米银与细菌接触过程中均能产生活性氧，并能氧化部分谷胱甘肽（GSH），活性氧诱发的氧化应激是纳米银杀菌机制之一；半胱氨酸的加入能极大抑制纳米银的杀菌效能，银离子的释放也是纳米银杀菌机制之一，并且推测银离子释放量的不同是导致不同形态纳米银杀菌性能差异的主要原因。
[Abstract]:Drinking water safety is closely related to human health, and bacteria exceeding the standard is the primary cause of unsafe drinking water. At present, the common drinking water sterilization technology has its own defects. Therefore, it is of practical significance to develop new methods and materials for drinking water sterilization. As a new bactericidal material, silver nanoparticles have the characteristics of high efficiency, wide spectrum and safety, and have potential application prospect in the field of drinking water sterilization. It was found that the morphology of nano-silver had an important effect on its properties, but the relationship between the morphology of nano-silver and its bactericidal properties had not been thoroughly studied. Therefore, in this paper, the morphology of silver nanoparticles controllable synthesis, antibacterial and bactericidal properties of the study, in order to provide a basis for the application of nano-silver drinking water sterilization technology. The main results and conclusions are as follows: silver nanostructures can be prepared rapidly by microwave heating with 20 mL ethylene glycol as reducing agent 90 mg silver nitrate as silver source. The nano-silver with different morphologies can be selectively synthesized by adding chlorine ion to control the reaction rate of the synthesis system and under the appropriate reaction time. At low NaCl dosage (less than 0.1mg), quasi spherical silver nanoparticles were obtained; at moderate NaCl dosage level (1mg), silver cube was the main product; at high NaCl dosage level (5mg), silver nanowires were obtained. The optimum synthesis conditions of silver cube were as follows: dosage of sodium chloride 0.5-1 mg, reaction time 2 min, and the optimum synthesis conditions of silver nanowires were: dosage of sodium chloride 5 mg, reaction time 3 min 30 s. The morphology of silver nanocrystalline was characterized by XRD- UV-Vis-SAED. The results showed that the diameter of spherical nanocrystalline silver was 60 卤15nm, the side length of silver cube was 55 卤10nm, and the diameter of silver nanowire was 60 卤10nm, the length of silver nanowire was 2-4um. The bacteriostatic and bactericidal effects of the three forms of silver nanoparticles on Escherichia coli were enhanced with the prolongation of the concentration and reaction time of silver nanoparticles. Silver cube has the best bactericidal efficacy, spherical silver is the second, silver nanowires have the weakest bactericidal effect. The minimum bactericidal concentration of silver cube and spherical silver nanocrystalline was 75ugr / mL and 100ugr / mL for E. coli with 106CUFP / mL, respectively, while the concentration of silver nanowires was not MICM in the range of 0 ~ 100ugr / mL. When the concentration of silver nanoparticles was 50ugr / mL, the adaptation period of E. coli was prolonged by silver cube for more than 12 hours, the spherical silver nanoparticles for 9 hours, and silver nanowires for only 6 hours. For 1 min, the silver cube of 25ug-mL and the spherical silver of 100ug-mL could completely inactivate Escherichia coli, but the silver nanowires could not completely inactivate the bacteria even when the concentration reached 100ugr / mL. The bactericidal properties of silver nanoparticles are not only related to their morphology, but also to their crystal planes. Compared with silver nanoparticles, silver nanowires are confined to their one-dimensional nanostructures, with large aspect ratio and relatively inadequate contact with bacteria, which leads to their weaker bactericidal properties, and the {100} crystal plane with higher reactivity of silver cube has better bactericidal effect. The {111} crystal plane exposed to spherical silver is relatively stable, so the bactericidal effect is relatively poor. Reactive oxygen species (Ros) and partial glutathione (GSH) can be oxidized during contact with bacteria. Oxidative stress induced by Ros is one of the bactericidal mechanisms of nano-silver, and cysteine can greatly inhibit the bactericidal efficacy of nanocrystalline silver. The release of silver ions is also one of the bactericidal mechanisms of nano-silver, and it is speculated that the difference in the amount of silver ions released is the main reason leading to the differences of bactericidal properties of nano-silver in different forms.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU991.2

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