摘要
针对纳米ZnO在制备以及使用的过程中极易发生团聚从而影响其抗菌性能这一缺点,设计实验使得纳米ZnO在溶胶凝胶过程中与多孔SiO2进行复合。通过扫描电子显微镜(Scanning electron microscope, SEM)以及透射电子显微镜(Transmission electron microscopy, TEM)等可以发现,ZnO很好地复合在多孔SiO2的骨架上并且分散得较为均匀。通过表面积测试(Brunner‑emmet‑teller measurement, BET)以及光致发光光谱(Photoluminescence spectrum,PL)的测试可以发现,复合材料的比表面积得到提高且光学性能加强。通过菌落计数法探究复合材料与单组分纳米ZnO的抗菌性能差异以及复合材料中纳米ZnO含量的变化导致的抗菌性能的变化。结论证明,当纳米ZnO与多孔SiO2进行复合之后,材料的抗菌性能得到了极大的提高,抑菌率超过了99%。
细菌的感染和传播一直是一个巨大的社会隐患,其对人类的危害与日俱增。自从细菌被发现以来,人类已经与它们斗争了数百
无机抗菌材料主要包括金属抗菌材料和金属氧化物抗菌材料,一般通过生成活性氧离子、释放抗菌离子和纳米颗粒内化等方
作为一种抗菌材料,ZnO不仅价格低廉,而且具有优良的光学性能,能有效吸收光能对微生物进行催化灭活。此外,特别是在水介质中,ZnO可以缓慢释放Z
多孔SiO2材料因其孔隙结构优秀、合成制备方法简单便捷、性能比较稳定等优点可以作为一种良好的催化载体,其骨架结构主要由二氧化硅纳米颗粒组成。这种参考SiO2气凝胶的多孔SiO2材料具有孔隙率高、比表面积高以及密度低等结构特
本文将ZnO纳米颗粒添加到二氧化硅凝胶前驱体中,然后将其混合干燥制备多孔SiO2负载纳米ZnO复合材料,ZnO纳米颗粒负载多孔SiO2网状结构上,增强纳米颗粒的分散性。由于ZnO纳米颗粒的分散性加强,其与细菌的接触面积也因此而增大,此外,ZnO纳米颗粒与光的接触面积也会增大,光催化效率有所提高,综合导致了抗菌性能的增强。采用XRD、EDS、SEM和TEM对多孔SiO2负载纳米ZnO复合材料的物相组成、微观结构进行了表征。采用紫外‑可见吸收光谱和光致发光光谱对多孔SiO2负载纳米ZnO复合材料的光学性能进行测试。最后,在研究复合材料的抗菌性能时,主要抑制的细菌是大肠杆菌和金黄色葡萄球菌。
室温下称取14.2 g 九水合硅酸钠3份,放入3个烧杯中,加入去离子水20 g。将烧杯放入搅拌机中磁力搅拌6 h,使其完全溶解。考虑到ZnO会与盐酸发生反应,在不同烧杯中加入不同含量略过量的ZnO纳米颗粒。第一个烧杯中加入8 g ZnO纳米颗粒,第二个烧杯中加入10 g ZnO纳米颗粒,第三个烧杯中加入12 g ZnO纳米颗粒。通过滴管,向烧杯中逐滴加入3 mol/L的盐酸,直到烧杯中的溶液开始凝胶,然后停止加入。制备了纳米ZnO/SiO2凝胶,接着在烧杯中加入20 ml丙酮溶液,促进复合凝胶在烧杯中的老化。然后在烧杯中加入20 ml无水乙醇,促进复合凝胶的老化和溶剂交换,浸泡时间为12 h;将烧杯放入烘箱中,烘箱温度设置为80 ℃烘干4 h,再将烘箱温度设置为120 ℃烘干2 h,最终成功制备出多孔SiO2负载纳米ZnO复合材料。
通过X射线衍射(X‑ray diffraction,XRD)测定复合材料的物相组成。在XRD表征中,选择铜靶作为辐射源,辐射波长为1.540 56 Å,步长为0.02。衍射过程中2θ角的测量范围为5°~80°。
采用扫描电镜(Scanning electron microscope, SEM) (Hitachi Limited, s‑4800)观察复合材料的微观结构。将导电条提前粘在样品杯上,然后将纳米复合材料固定在导电条上。首先对它们进行喷金处理,然后放在扫描电子显微镜下观察。同时,其内置的X射线能谱仪(Energy disperse spectroscopy,EDS)可以分析复合材料中元素的分布和含量,确定是否有杂质以及各元素的原子百分比。
采用高分辨透射电镜(Transmission electron microscopy,TEM)对复合材料的微观结构进行表征。用超声波和分散剂将粉末分散,并将其滴在载体网上,在电子显微镜下观察。
采用菌落计数法对多孔SiO2负载纳米ZnO复合材料的抗菌性能进行测试和分析。具体的实验方法是参照GB/T 21520─2008《纳米无机材料抗菌性能检测方法》附录A,即对纳米粉体抗菌性能的测定本标准进行测试。试验的具体步骤如下:首先取12 g 琼脂粉体溶解于500 ml去离子水中,而后121 ℃高压蒸气消毒后备用。将琼脂溶液均匀涂覆在培养皿中,待冷却待用。取第5代~第7代的菌液作为实验使用的菌株。取0.01 g的测试样品放置于小试样管中,而后用移液枪取500 μl的菌液滴加进试样管中与测试样品接触抗菌。分别在1、 3、 6和12 h四个时间段使用移液枪吸取100 μl的样品液体滴加在琼脂培养基上,而后使用三角玻棒将琼脂培养基上的样品液体涂覆均匀。将琼脂培养基放置在恒温培养箱中,培养箱的温度设置为37.5 ℃,待12 h后取出琼脂培养基对其上的菌落数进行计数。
(1) |
式中:R为抗菌率,单位为%; A为对照组存活菌落数量,单位为个; B为实验组存活菌落数量,单位为个。
多孔SiO2负载纳米ZnO复合材料的XRD测试结果如

图1 多孔SiO2负载纳米ZnO复合材料的XRD图谱
Fig.1 XRD pattern of porous SiO2 supported nano ZnO composites

图2 多孔SiO2负载纳米ZnO复合材料的EDS图像
Fig.2 EDS images of porous SiO2 supported nano ZnO composites
从

图3 ZnO纳米颗粒和多孔SiO2负载纳米ZnO复合材料的SEM图像
Fig.3 SEM images of ZnO nanoparticles and porous SiO2 supported nano ZnO composites

图4 不同尺度的多孔SiO2负载纳米ZnO复合材料的TEM图像
Fig.4 TEM images of porous SiO2 supported nano ZnO composites at different scales

图5 不同晶格间距的多孔SiO2负载纳米ZnO复合材料的HRTEM图像
Fig.5 HRTEM images of porous SiO2 supported nano ZnO composites with different lattice spacing

图6 ZnO纳米颗粒及多孔SiO2负载纳米ZnO复合材料的N2吸附-脱附等温线和孔径分布图
Fig.6 N2 adsorption-desorption isotherms and pore size distribution of ZnO nanoparticles and porous SiO2 supported nano ZnO composites
项目 | 比表面积/( | 平均孔径/nm | 孔体积/(c |
---|---|---|---|
ZnO纳米颗粒 | 25.69 | 3.29 | 0.09 |
8 g ZnO 纳米颗粒/多孔SiO2 | 76.22 | 29.65 | 0.30 |
10 g ZnO纳米颗粒/多孔SiO2 | 82.33 | 34.59 | 0.40 |
12 g ZnO纳米颗粒/多孔SiO2 | 94.59 | 35.61 | 0.40 |
通过对ZnO纳米颗粒以及不同含量多孔SiO2负载纳米ZnO复合材料进行光致发光光谱(Photoluminescence spectrum, PL)测试来评估光生电子空穴对的分离效率。通常,低 PL 强度通常表示光生电子空穴对的重组率较低,半导体光催化剂的光催化活性较高。半导体光催化剂的光催化活性取决于光生载流子的捕获和寿命。

图7 ZnO纳米颗粒及不同含量的多孔SiO2负载纳米ZnO复合材料的光致发光光谱图谱
Fig.7 PL profiles of ZnO nanoparticles and porous SiO2 supported nano ZnO composites with different contents

图8 多孔SiO2负载纳米ZnO复合材料的荧光发射衰减图谱
Fig.8 Fluorescence emission attenuation pattern of porous SiO2 supported nano ZnO composites
(2) |
式中τ为复合材料的荧光寿命,单位为纳秒(ns);t1、t2分别为双指数函数拟合中的长寿命、短寿命;A1、A2为前两者的权重系数。
经过计算得出,多孔SiO2负载纳米ZnO复合材料的荧光寿命为3.565 8 ns。由已报道的研
为了评价复合材料在水中的分散性,对复合材料做了亲水性测试,

图9 多孔SiO2负载纳米ZnO复合材料的不同介质的接触角测试
Fig.9 Contact angles of porous SiO2 supported nano ZnO composites with different media
本文中用于抗菌实验的细菌为大肠杆菌以及金黄色葡萄球菌。从

图10 多孔SiO2的抗菌测试:平板计数法
Fig.10 Antibacterial test of porous SiO2: Plate counting method

图11 ZnO的抗菌测试:平板计数法
Fig.11 Antibacterial test of ZnO: Plate counting method
图

图12 8 g ZnO/多孔SiO2复合材料的抗菌测试:平板计数法
Fig.12 Antibacterial test of 8 g ZnO/ porous SiO2 composites: Plate counting method

图13 10 g ZnO/多孔SiO2复合材料的抗菌测试:平板计数法
Fig.13 Antibacterial test of 10 g ZnO/ porous SiO2 composites: Plate counting method

图14 12 g ZnO/多孔SiO2复合材料的抗菌测试:平板计数法
Fig.14 Antibacterial test of 12 g ZnO/ porous SiO2 composites: Plate counting method
由于复合材料中的多孔SiO2几乎不具有抗菌性能,因此复合材料的抗菌性能都来自ZnO纳米颗粒。复合材料的抗菌机理主要有两个方面:一是DNA损伤杀菌机理。当ZnO与细菌接触时,Z
通过在溶胶‑凝胶的前驱体中加入一定量的纳米ZnO,使纳米ZnO充分分散在多孔SiO2中,制备多孔SiO2负载纳米ZnO复合材料。样品的微观结构表征表明,添加的纳米ZnO尺寸为20~30 nm,广泛分布在多孔SiO2的骨架上。与单组分纳米ZnO相比,复合材料的比表面积有了明显提高,光催化性能和抗菌性能均得到了很大的提高,抑菌率可达到99%以上。综上所述,多孔SiO2可以大大增加ZnO纳米颗粒的分散性,增强ZnO的抗菌性能。此外,多孔SiO2由于制备成本低,可广泛应用于涂料和医疗领域。
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