Khoury Christopher G, Vo-Dinh Tuan
Fitzpatrick Institute for Photonics, Duke University, Durham, NC 27708, USA ; Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
J Phys Chem C Nanomater Interfaces. 2008;2008(112):18849-18859. doi: 10.1021/jp8054747.
The controlled synthesis of high-yield gold nanostars of varying sizes, their characterization and use in surface-enhanced Raman scattering (SERS) measurements are reported for the first time. Gold nanostars ranging from 45 to 116-nm in size were synthesized in high-yield, physically modeled and optically characterized using transmission and scanning electron microscopy and UV-Visible absorption spectroscopy. The nanostar characterization involved both studying morphology evolution over time and size as a function of nucleation. The nanostars properties as substrates for SERS were investigated and compared with respect to size. As the overall star size increases, so does the core size, the number of branches and branch aspect ratio; the number of branch tips per star surface area decreases with increasing size. The stars become more inhomogeneous in shape, although their yield is high and overall size remains homogeneous. Variations in star size are also accompanied by shifts of the long plasmon band in the NIR region, which hints towards tuning capabilities that may be exploited in specific SERS applications. The measured SERS enhancement factors suggest an interesting correlation between nanostar size and SERS efficiencies, and were relatively consistent across different star samples, with the enhancement factor estimated as 5×10 averaged over the 52-nm nanostars for 633-nm excitation.
首次报道了不同尺寸高产率金纳米星的可控合成、表征及其在表面增强拉曼散射（SERS）测量中的应用。合成了尺寸在45至116纳米之间的高产率金纳米星，利用透射电子显微镜、扫描电子显微镜和紫外-可见吸收光谱对其进行了物理建模和光学表征。纳米星的表征包括研究随时间的形态演变以及作为成核函数的尺寸。研究了纳米星作为SERS基底的性质，并就尺寸进行了比较。随着纳米星整体尺寸的增加，核心尺寸、分支数量和分支纵横比也增加；每单位表面积的分支尖端数量随尺寸增加而减少。尽管纳米星的产率很高且整体尺寸保持均匀，但它们的形状变得更加不均匀。纳米星尺寸的变化还伴随着近红外区域长等离子体带的移动，这暗示了在特定SERS应用中可能利用的调谐能力。测量的SERS增强因子表明纳米星尺寸与SERS效率之间存在有趣的相关性，并且在不同的纳米星样品中相对一致，对于633纳米激发，在52纳米纳米星上平均估计增强因子为5×10 。
