银纳米颗粒及其复合物的生物制备和性能表征

发布时间：2018-03-14 22:34

本文选题：银纳米粒子　切入点：(Ag/Ag~+/Ag~(3+))复合纳米粒子　出处：《陕西科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：银纳米颗粒(AgNPs)及其复合纳米颗粒具有优异的导电性能、良好的抗菌性、小尺寸效应及量子尺寸效应等,使其广泛应用于医疗、电子、食品等行业。AgNPs的制备方法主要有物理法,化学法和生物法。与物理法和化学法相比,生物法因具有高效、快速、简单易行、环境友好及价格低廉等诸多优点而倍受人们关注。目前微生物法研究较多,植物法却鲜为报道,为了开拓新的AgNPs及复合NPs的植物制备法,本研究选取绿茶、银杏叶、苹果渣及石榴皮提取液为还原剂和稳定剂合成AgNPs及其复合NPs。主要研究内容及其结果如下:(1)绿茶、银杏叶、苹果渣、石榴皮等植物水提取液与AgNO_3溶液混合,制备AgNPs或(Ag/Ag~+/Ag~(3+))NPs;借助UV-vis、XRD和TEM等仪器对所得纳米粒子进行表征,利用FTIR分析检测植物提取液合成纳米粒子前后含有的大分子物质变化;通过单因素实验确定了植物法合成AgNPs及其复合物的适宜条件。结果表明:以绿茶提取液为原料,合成条件为:料液比1:30(g/mL),AgNO_3浓度为10 mmol/L,反应液体积比为1:5(mL/mL),所得AgNPs的平均尺寸为13.6 nm;以苹果渣提取液为原料,合成条件为:料液比1:20(g/mL),AgNO_3浓度为15 mmol/L,反应液体积比为1:4(mL/mL),得到平均尺寸为16.0 nm的AgNPs;且这两种植物提取液合成的AgNPs结晶度较高,形貌规整,呈球形或近似球形,大小均匀,颗粒分散。以银杏叶提取液为原料,合成条件为:料液比1:50(g/mL),AgNO_3浓度为5 mmol/L,反应液体积比为1:8(mL/mL),制备的(Ag/Ag~+/Ag~(3+))NPs均匀分散结晶度较高,为球形或近似球形,其中AgNPs的平均尺寸为13.8 nm,AgONPs的平均尺寸为24.6 nm;以石榴皮提取液为原料,得到(Ag/Ag~+/Ag~(3+))NPs,合成条件为:溶液pH=8,AgNO_3浓度为10 mmol/L,料液比为1:15(g/mL),得到的复合NPs较分散,结晶度较好,尺寸分布在18~35 nm之间;FTIR分析表明,植物提取物中的多酚类,黄酮类,维生素,蛋白质等大分子物质在纳米粒子的形成过程起还原和保护作用。(2)以Vc作为对比,测定了植物水提取物对·OH、O_2~-·及DPPH自由基的清除率,确定提取物抗氧化性的强弱;测定了合成条件下Ag~+的还原率;测定了研究所得AgNPs在溶液中的稳定性。结果表明,绿茶提取液的抗氧化性强于Vc,对自由基有很强的清除能力,其余3种植物提取物的稍弱;植物提取物对4种自由基清除率的实验结果表明,绿茶、银杏叶等被选取的4种植物提取物对DPPH自由基的清除效果最好;通过测定可得Ag~+的还原率或转化率均可达到99%以上;合成的AgNPs在溶液中较稳定。(3)利用抑菌圈法和MIC值检验了合成的AgNPs及(Ag/Ag~+/Ag~(3+))NPs对E.coli和S.aureus的抑菌性能,结果表明,AgNPs对革兰氏阳性菌和革兰氏阴性菌的生长均有较好的抑制能力,且(Ag/Ag~+/Ag~(3+))NPs的抑菌能力约是AgNPs的2~3倍;AgNPs或(Ag/Ag~+/Ag~(3+))NPs对E.coli和S.aureus的MIC值约为1.15×10~(-4) mol/L或约为2.90×10~(-5) mol/L。纳米粉体经200,350,500°C热处理后,观察其XRD图谱变化及对其衍射峰参数的分析发现,AgNPs及其复合NPs的尺寸均增大,结晶度均提高,且(Ag/Ag~+/Ag~(3+))NPs中Ag~+和Ag~(3+)的存在形态均遭到破坏;借助ESEM观察发现,纳米粉体存在形貌发生改变;通过SEM观测发现,随着温度的升高纳米粒子开始聚集,AgNPs的平均粒径由15 nm左右增大至100 nm左右,(Ag/Ag~+/Ag~(3+))NPs的平均粒径由20 nm左右增大至130 nm左右。500°C热处理后,AgNPs及其复合NPs的抑菌性能均明显减弱,处理前的抑菌能力基本是处理后的2~3倍;热处理后,AgNPs对E.coli或S.aureus的MIC增大至2.31×10~(-4) mol/L左右,(Ag/Ag~+/Ag~(3+))NPs的MIC值增大至5.80×10~(-5)mol/L左右。所以,温度会影响或改变纳米粒子的存在形态、尺寸、结晶度和抑菌性能。对比AgNPs及(Ag/Ag~+/Ag~(3+))NPs热处理前后的FTIR吸收峰发现,多酚类,黄酮类,蛋白质等大分子物质相应的吸收峰均消失,说明这些大物质分子覆盖在纳米粒子表面,且被高温分解。(4)通过对纳米粒子的形成机理及抑菌机理的探索发现,AgNPs及(Ag/Ag~+/Ag~(3+))NPs合成过程中遵循生物大分子与Ag~+发生吸附、还原和络合的过程;其抑菌机理具有与菌体细胞多位点结合的特点;该机理为植物法合成AgNPs及复合NPs提供新思路和理论基础。
[Abstract]:Silver nanoparticles (AgNPs) excellent conductive properties and composite nano particles have good antibacterial property, small size effect and quantum size effect, which is widely used in medical, electronic, food and other industries.AgNPs preparation methods mainly include physical method, chemical method and biological method and physical method and compared. Chemical method, biological method is efficient, fast, simple, environmentally friendly and low price and many other advantages. At present, people pay more attention to microbial research more, but plant method is seldom reported, in order to open up a new AgNPs and NPs composite plant preparation method, this study selected Green Tea, Ginkgo biloba, apple pomace as follows pomegranate peel extract as the reducing agent and stabilizer synthesis of AgNPs composite NPs. and its main contents and results: (1) Green Tea, Ginkgo biloba extract, apple pomace, and AgNO_3 mixed solution of pomegranate and other water plants, the preparation of AgNPs (or Ag/Ag~+ /Ag~ (3+) NPs); with the help of UV-vis, the nanoparticles were characterized by XRD and TEM instruments, detection and analysis of plant extracts macromolecules changes before and after the synthesis of nanoparticles using FTIR liquid containing plant; synthesis of AgNPs and its composite suitable conditions were determined by single factor experiments. The results showed that: Green Tea extracts the raw material, the synthesis conditions were: liquid ratio (g/mL), AgNO_3 1:30 concentration was 10 mmol/L, the volume of reaction liquid ratio of 1:5 (mL/mL), the average size of the AgNPs was 13.6 nm; apple pomace extract as raw material, the synthesis conditions were: liquid ratio (g/mL), AgNO_3 1:20 concentration was 15 mmol/L the reaction volume, liquid ratio 1:4 (mL/mL), the average size is 16 nm AgNPs; and the two plant extracts synthesized AgNPs high degree of crystallinity, morphology, spherical or nearly spherical, uniform size, particle dispersion. Ginkgo biloba extract as raw material, synthesis conditions As the ratio of material to liquid, the concentration of AgNO_3 (g/mL) 1:50 is 5 mmol/L, the volume of reaction liquid ratio of 1:8 (mL/mL), the preparation of (Ag/Ag~+/Ag~ (3+) NPs) dispersed high degree of crystallinity, spherical or nearly spherical, the average size of AgNPs is 13.8 nm, the average size of 24.6 AgONPs nm; to extract of pomegranate peel as raw material, obtained (Ag/Ag~+/Ag~ (3+) NPs), the synthesis conditions are: solution pH=8, AgNO_3 concentration was 10 mmol/L, the ratio of liquid to 1:15 (g/mL), compound NPs obtained more dispersed, good crystallinity and size distribution in 18~35 nm; FTIR analysis showed that polyphenols class, plant extracts, flavonoids, vitamin, protein and other substances in the formation of nanoparticles process reduction and protection. (2) using Vc as contrast, plant water extract on OH determination of scavenging O_2~- and DPPH free radicals, determine the antioxidative activity of strength; Determination of synthesis under the condition of Ag~+ The reduction rate of income; stability of AgNPs in solution were determined. The results showed that the extraction of antioxidant Green Tea liquid is stronger than Vc, has a strong ability to scavenge free radicals, the other 3 kinds of plant extracts. Green Tea; plant extracts of 4 kinds of free radical scavenging rate of the experimental results show that, the best of DPPH free radical scavenging effect of 4 kinds of plant extracts of Ginkgo biloba leaves were selected; through the determination of available Ag~+ reduction rate or conversion rate can reach above 99%; the synthesis of AgNPs was stable in solution. (3) using the inhibition zone method and MIC value test of the synthesis of AgNPs and (Ag/Ag~+/Ag~ (3+)) the results showed that the antibacterial properties of NPs, E.coli and S.aureus, AgNPs had better inhibitory ability against gram positive and gram negative bacteria growth, and (Ag/Ag~+/Ag~ (3+)) antibacterial ability of NPs is about 2~3 times of AgNPs; or AgNPs (Ag/Ag~+/Ag~ (3+) NPs) on E.coli and S. The aureus MIC value is about 1.15 * 10~ (-4) or mol/L is about 2.90 * 10~ (-5) mol/L. nano powder by 200350500 DEG C after heat treatment, observe the change of the spectrum and XRD analysis of the diffraction peak parameters, AgNPs and composite NPs size increased, the crystallinity increased, and the (Ag /Ag~+/Ag~ (3+) Ag~+) and Ag~ NPs (3+) forms were destroyed; with the aid of the ESEM observation found that the nano powder has the morphology changes; through SEM observation found that with the increase of temperature of the nanoparticles began to gather, the average particle size of the AgNPs increased from about 15 nm to about 100 nm, (Ag/Ag~+/Ag~ (3+)) NPs average particle size of from about 20 nm increased to 130 nm about.500 DEG C after heat treatment, and the antibacterial properties of AgNPs composite NPs significantly decreased, antibacterial ability before treatment is basically 2~3 times after treatment; after heat treatment, the AgNPs of E.coli or S.aureus increased to 2.31 MIC * 10~ (-4) M About ol/L (Ag/Ag~+/Ag~ (3+) NPs) MIC value increased to 5.80 * 10~ (-5) mol/L. So, the temperature will affect or change the existing form, particle size, crystallinity and antibacterial properties. Comparison of AgNPs and (Ag/Ag~+/Ag~ (3+) NPs) before and after heat treatment of the absorption peak of FTIR found that polyphenols class, flavonoids, proteins and other macromolecules corresponding to the absorption peak disappeared, indicating that these large molecules covered on the surface of nanoparticles, and is decomposed at high temperature. (4) by exploring the formation mechanism and the antibacterial mechanism of the nanoparticles, and AgNPs (Ag/Ag~+/Ag~ (3+)) NPs synthesis followed in the process of biological macromolecules with the occurrence of Ag~+ adsorption, reduction and complexation; its antibacterial mechanism has the characteristics of cell and multilocus combined; the mechanism to provide new ideas and theoretical basis for plant synthesis of AgNPs and NPs composite.

【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O614.122;TB383.1

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