Lim Soo Hyeon, Park Youmie
College of Pharmacy and Inje Institute of Pharmaceutical Sciences and Research, Inje University, 197 Inje-ro, Gimhae, Gyeongnam 50834, Republic of Korea.
J Nanosci Nanotechnol. 2018 Jan 1;18(1):659-667. doi: 10.1166/jnn.2018.13982.
Green strategies to synthesize gold nanoparticles have attracted a substantial amount of attention because global sustainability is a focal issue in many research areas. In the present study, rosmarinic acid was utilized as a reducing agent to reduce gold ions to gold nanoparticles. The characteristic surface plasmon resonance of gold nanoparticles was observed at 532 nm with a pink-colored colloidal solution. High-resolution transmission electron microscopy (HR-TEM) revealed the presence of spherical nanoparticles along with triangular nanoplates. The average nanoparticle size was determined as 30.46 ± 6.25 nm from HR-TEM images, and the hydrodynamic size was measured as 31.90 nm. An evaluation of the shelf stability indicated that the colloidal solution retained an excellent stability for two weeks at room temperature. A large negative value for the zeta potential (-24.09 ±3.97 mV) also suggested the excellent stability of the colloidal solution. The face-centered cubic structure of gold nanoparticles was confirmed by the strong diffraction peaks in the high-resolution X-ray diffraction analysis. Hydroxyl and ketone functional groups in rosmarinic acid were most likely involved in the synthesis of gold nanoparticles. Catalytic activity was evaluated in 4-nitrophenol, methylene blue and methyl orange reduction reactions in the presence of sodium borohydride. The order of catalytic activity for reduction reactions was methylene blue > methyl orange > 4-nitrophenol. These three reactions were conducted at four different reaction temperatures (room temperature, 30 °C, 40 °C and 50 °C). The catalytic activity was temperature-dependent, and the highest rate constant was obtained in the methylene blue reduction reaction at 50 °C.
由于全球可持续发展是许多研究领域的焦点问题，因此合成金纳米粒子的绿色策略已引起了广泛关注。在本研究中，迷迭香酸被用作还原剂，将金离子还原为金纳米粒子。在532nm处观察到金纳米粒子的特征表面等离子体共振，呈现粉红色胶体溶液。高分辨率透射电子显微镜（HR-TEM）显示存在球形纳米粒子以及三角形纳米片。根据HR-TEM图像确定纳米粒子的平均尺寸为30.46±6.25nm，流体动力学尺寸测量为31.90nm。货架稳定性评估表明，胶体溶液在室温下两周内保持了优异的稳定性。zeta电位的大负值（-24.09±3.97mV）也表明胶体溶液具有优异的稳定性。高分辨率X射线衍射分析中的强衍射峰证实了金纳米粒子的面心立方结构。迷迭香酸中的羟基和酮官能团最有可能参与了金纳米粒子的合成。在硼氢化钠存在下，对4-硝基苯酚、亚甲基蓝和甲基橙还原反应的催化活性进行了评估。还原反应的催化活性顺序为亚甲基蓝>甲基橙>4-硝基苯酚。这三个反应在四个不同的反应温度（室温、30℃、40℃和50℃）下进行。催化活性与温度有关，在50℃下亚甲基蓝还原反应中获得了最高的速率常数。
