Choi Yoonho, Kang Sehyeon, Cha Song-Hyun, Kim Hyun-Seok, Song Kwangho, Lee You Jeong, Kim Kyeongsoon, Kim Yeong Shik, Cho Seonho, Park Youmie
College of Pharmacy, Inje University, 197 Inje-ro, Gimhae, Gyeongnam, 50834, Republic of Korea.
Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
Nanoscale Res Lett. 2018 Jan 17;13(1):23. doi: 10.1186/s11671-018-2436-2.
A green synthesis of gold and silver nanoparticles is described in the present report using platycodon saponins from Platycodi Radix (Platycodon grandiflorum) as reducing agents. Platycodin D (PD), a major triterpenoidal platycodon saponin, was enriched by an enzymatic transformation of an aqueous extract of Platycodi Radix. This PD-enriched fraction was utilized for processing reduction reactions of gold and silver salts to synthesize gold nanoparticles (PD-AuNPs) and silver nanoparticles (PD-AgNPs), respectively. No other chemicals were introduced during the reduction reactions, providing an entirely green, eco-friendly, and sustainable method. UV-visible spectra showed the surface plasmon resonance bands of PD-AuNPs at 536 nm and PD-AgNPs at 427 nm. Spherically shaped nanoparticles were observed from high-resolution transmission electron microscopy with average diameters of 14.94 ± 2.14 nm for PD-AuNPs and 18.40 ± 3.20 nm for PD-AgNPs. Minor triangular and other polygonal shapes were also observed for PD-AuNPs along with spherical ones. Atomic force microscopy (AFM) images also demonstrated that both nanoparticles were mostly spherical in shape. Curvature-dependent evolution was employed to enhance the AFM images and precisely measure the sizes of the nanoparticles. The sizes were measured as 19.14 nm for PD-AuNPs and 29.93 nm for PD-AgNPs from the enhanced AFM images. Face-centered cubic structures for both nanoparticles were confirmed by strong diffraction patterns from high-resolution X-ray diffraction analyses. Fourier transform infrared spectra revealed the contribution of -OH, aromatic C=C, C-O, and C-H functional groups to the synthesis. Furthermore, the catalytic activity of PD-AuNPs was assessed with a reduction reaction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. The catalytic activity results suggest the potential application of these gold nanoparticles as catalysts in the future. The green strategy reported in this study using saponins as reducing agents will pave new roads to develop novel nanomaterials with versatile applications.
本报告描述了一种绿色合成金和银纳米颗粒的方法，该方法使用桔梗（桔梗）中的桔梗皂苷作为还原剂。通过对桔梗水提取物进行酶促转化，富集了主要的三萜类桔梗皂苷桔梗皂苷D（PD）。该富含PD的级分分别用于处理金盐和银盐的还原反应，以合成金纳米颗粒（PD-AuNPs）和银纳米颗粒（PD-AgNPs）。在还原反应过程中未引入其他化学物质，提供了一种完全绿色、环保且可持续的方法。紫外可见光谱显示PD-AuNPs的表面等离子体共振带在536nm处，PD-AgNPs的表面等离子体共振带在427nm处。高分辨率透射电子显微镜观察到球形纳米颗粒，PD-AuNPs的平均直径为14.94±2.14nm，PD-AgNPs的平均直径为18.40±3.20nm。PD-AuNPs除了球形外，还观察到少量三角形和其他多边形形状。原子力显微镜（AFM）图像也表明，两种纳米颗粒大多为球形。采用曲率相关演化来增强AFM图像并精确测量纳米颗粒的尺寸。从增强的AFM图像中测得PD-AuNPs的尺寸为19.14nm，PD-AgNPs的尺寸为29.93nm。高分辨率X射线衍射分析的强衍射图谱证实了两种纳米颗粒的面心立方结构。傅里叶变换红外光谱揭示了-OH、芳香族C=C、C-O和C-H官能团对合成的贡献。此外，在硼氢化钠存在下，通过4-硝基苯酚还原为4-氨基苯酚的反应评估了PD-AuNPs的催化活性。催化活性结果表明这些金纳米颗粒未来作为催化剂的潜在应用。本研究报道的使用皂苷作为还原剂的绿色策略将为开发具有多种应用的新型纳米材料铺平道路。
