每枚纳米杨桃大约长550nm，图片来自莱斯大学的Leo Vigderman和Eugene Zubarev。
形似杨桃的纳米棒(star-fruit-shaped nanorod)，是研究人员在实验室中利用横截面为五叶型的金纳米线(gold nanowire)培养出来的，能够显著性地改善化学物检测技术。
这项研究可能有助于改善对有机分子---包括诸如癌症之类的疾病的生物标记物---的检测。来自美国德克萨斯州休斯敦市莱斯大学的Eugene Zubarev说，“人们对很多癌症进行的检测能否成功取决于所采取的技术能够检测到的生物标记物最低浓度。”
表面增强拉曼光谱(surface-enhanced Raman spectroscopy)是一种比较流行的用于检测有机分子的技术。当利用表面增强拉曼光谱进行检测时，这些纳米棒返送回的信号强度比常规的表面光滑的纳米棒的高25倍。拉曼光谱通过测定化合物散射单色光(通常由激光源产生)的方式来确定它们的分子结构。
这些纳米杨桃利用金能够局部增强电磁场的能力来提高返送回的信号强度。“电磁场将集中在存在的特定缺陷处，比如纳米杨桃带有的尖锐的角，从而有助于检测极低浓度的有机分子”，Zubarev说，“如果我们能够修饰这些纳米杨桃的表面粗糙度让靶标生物分子选择性地结合到我们设计出的表面粗糙的纳米棒上，那么我们就能够开始关注极低浓度的DNA或癌症生物标记物。” (生物谷：towersimper编译)
doi:10.1021/la300218z
PMC:
PMID:
Starfruit-Shaped Gold Nanorods and Nanowires: Synthesis and SERS Characterization
Leonid Vigderman and Eugene R. Zubarev
Recently, branched and star-shaped gold nanoparticles have received significant attention for their unique optical and electronic properties, but most examples of such nanoparticles have a zero-dimensional shape with varying numbers of branches coming from a quasi-spherical core. This report details the first examples of higher-order penta-branched gold particles including rod-, wire-, and platelike particles which contain a uniquely periodic starfruitlike morphology. These nanoparticles are synthesized in the presence of silver ions by a seed-mediated approach based on utilizing highly purified pentahedrally twinned gold nanorods and nanowires as seed particles. The extent of the growth can be varied, leading to shifts in the plasmon resonances of the particles. In addition, the application of the starfruit rods for surface-enhanced Raman spectroscopy (SERS) is demonstrated.
