【作者】 骆伟洁；

【导师】 朱军；

【作者基本信息】 南京农业大学 ， 微生物学， 2011， 硕士

【摘要】 纳米颗粒的粒径和形状经常受一些外部因素影响,如反应温度、时间、反应前体或者表面活性剂的浓度。如果不控制这些外部因素最终可能会导致纳米颗粒的生长不受控制,还可能失去其纳米尺度的一些特性。我们发现一种基于纳米金的自我催化、自我限制的系统,并且探究了纳米金的类葡萄糖氧化酶活性。纳米金的米曼二氏常数为6.97mM,高于葡萄糖氧化酶的4.87mM,说明它对葡萄糖的亲和力略低于葡萄糖氧化酶。值得注意的是,这种类葡萄糖氧化酶的活性在其他一些纳米材料中都没有发现,比如纳米银、二氧化钛、碳纳米管、四氧化三铁等。我们又对纳米金的这种活性进行了系统的研究。纳米金展示出对pH、温度的高度耐受性,同时在保存中也具有稳定性。而通过研究不同粒径的纳米金(13、20、30、50nm)的活性发现,其活性随着粒径的增加而减少。我们发现纳米金催化葡萄糖氧化时在原位产生过氧化氢,在氯金酸存在的情况下过氧化氢催化以纳米金为种子的生长。这个生长存在两个反馈因素：纳米金粒径增加后活性降低和产生的葡萄糖酸将纳米金表面钝化,实现其自我限制生长。在这个系统中,纳米金的粒径、形状和催化活性受到控制。我们希望这能提供一个纳米材料的可控合成和纳米药物自我调节的新方法,更深入地研究自然界中的自我限制系统。我们希望这能提供一个纳米材料可控合成和纳米药物自我调节的新方法,纳米金的葡萄糖氧化酶活性还能用于检测葡萄糖,从而应用于微生物发酵产物中葡萄糖含量的测定。更多还原

【Abstract】 Size and shape of nanoparticles are generally controlled by external influence factors such as reaction temperature, time, precursor, and/or surfactant concentration. Lack of external influence may eventually lead to unregulated growth of nanoparticles and possibly loss of their nanoscale properties. Here we report a gold nanoparticle (AuNPs)-based self-catalyzed and self-limiting system that exploits the glucose oxidase-like catalytic activity of AuNPs. The Michaelis (?) Menten constant (Km) of AuNPs was calculated to be 6.97 mM, which was slightly higher than GOx (4.87 mM) slightly lower affinity. Of note, the GOx-mimicking activity was not oberved in a range of interrogated nanomaterials, such as silver nanoparticles, TiO2 nanoparticles, carbon nanotubes, and Fe3O4 nanoparticles. We investigated the catalytic activity of AuNPs systematically. Interestingly, AuNPs exhibited superior pH, thermal, and storage stability to natural enzyme GOx. By using AuNPs of different size (13,20,30, and 50nm) at the same concentration, we found that the catalytic activity of AuNPs decreased along with their sizes. We find that the AuNP-catalyzed glucose oxidation in situ produces hydrogen peroxide (H2O2) that induces the AuNPs’seeded growth in the presence of chloroauric acid (HAuC14). This crystal growth of AuNPs is internally regulated via two negative feedback factors, size-dependent activity decrease of AuNPs and product (gluconic acid)-induced surface passivation, leading to a rapidly self-limiting system. Interestingly, the size, shape, and catalytic activities of AuNPs are simultaneously controlled in this system. We expect that it provides a new method for controlled synthesis of novel nanomaterials, design of "smart" self-limiting nanomedicine, as well as in-depth understanding of self-limiting systems in nature.更多还原