每枚納米楊桃大約長550nm,，圖片來自萊斯大學的Leo Vigderman和Eugene Zubarev,。
形似楊桃的納米棒(star-fruit-shaped nanorod)，是研究人員在實驗室中利用橫截面為五葉型的金納米線(gold nanowire)培養(yǎng)出來的,，能夠顯著性地改善化學物檢測技術,。
這項研究可能有助于改善對有機分子---包括諸如癌癥之類的疾病的生物標記物---的檢測。來自美國德克薩斯州休斯敦市萊斯大學的Eugene Zubarev說,，“人們對很多癌癥進行的檢測能否成功取決于所采取的技術能夠檢測到的生物標記物最低濃度,。”
表面增強拉曼光譜(surface-enhanced Raman spectroscopy)是一種比較流行的用于檢測有機分子的技術。當利用表面增強拉曼光譜進行檢測時,，這些納米棒返送回的信號強度比常規(guī)的表面光滑的納米棒的高25倍。拉曼光譜通過測定化合物散射單色光(通常由激光源產(chǎn)生)的方式來確定它們的分子結(jié)構(gòu),。
這些納米楊桃利用金能夠局部增強電磁場的能力來提高返送回的信號強度,。“電磁場將集中在存在的特定缺陷處，比如納米楊桃?guī)в械募怃J的角,，從而有助于檢測極低濃度的有機分子”,，Zubarev說，“如果我們能夠修飾這些納米楊桃的表面粗糙度讓靶標生物分子選擇性地結(jié)合到我們設計出的表面粗糙的納米棒上,，那么我們就能夠開始關注極低濃度的DNA或癌癥生物標記物,。” (生物谷：towersimper編譯)
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.
