Large-area periodic arrays of gold nanostars derived from HEPES-, DMF-, and ascorbic-acid-driven syntheses
Large-area periodic arrays of gold nanostars derived from HEPES-, DMF-, and ascorbic-acid-driven syntheses
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DOI：
10.1039/d0nr04141f
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发表时间：
2020-08-21
期刊：
影响因子：
6.7
通讯作者：
Neretina, Svetlana
中科院分区：
文献类型：
--
作者：
Demille, Trevor B.;Hughes, Robert A.;Neretina, Svetlana
由于臂从中心核心辐射，金纳米星代表了一类独特而迷人的纳米材料，从这些材料中可以获得非凡的等离子体性质。尽管它们与传感应用相关，但在真正周期性的阵列中，缺乏在大面积平面表面上制造均匀的纳米恒星群体的方法。在这里，通过形成近半球金种的六角形图案并随后将它们暴露在有利于胶体纳米STAR形成的液态化学环境中，展示了纳米STAR阵列的制备。三种不同的胶体纳米STAR方案被瞄准，其中HEPES、DMF和抗坏血酸代表了它们各自氧化还原化学中的关键试剂。只有DMF驱动的合成被证明很容易适应基于底物的平台，但当应用合成控制，如反应动力学、Ag(+)离子的添加和pH调节时，其他方法产生了类似纳米STAR的结构。因为纳米星是从近半球的种子中衍生出来的，所以它们获得了一种独特的几何形状，类似于传统的纳米星，但在其中段附近被截断了。对这种几何结构的等离子体激元性质的模拟表明，这种结构可以展示出比标准纳米STAR几何结构大七倍的最大近场强度，这一发现得到了表面增强拉曼散射(SERS)测量的证实，该测量显示了大的增强因子。这项研究将纳米恒星添加到可用于大面积周期阵列的纳米结构几何库中，并为具有更大增强作用的SERS衬底的纳米制造提供了一条潜在的途径。
With arms radiating from a central core, gold nanostars represent a unique and fascinating class of nanomaterials from which extraordinary plasmonic properties are derived. Despite their relevance to sensing applications, methods for fabricating homogeneous populations of nanostars on large-area planar surfaces in truly periodic arrays is lacking. Herein, the fabrication of nanostar arrays is demonstrated through the formation of hexagonal patterns of near-hemispherical gold seeds and their subsequent exposure to a liquid-state chemical environment that is conducive to colloidal nanostar formation. Three different colloidal nanostar protocols were targeted where HEPES, DMF, and ascorbic acid represent a key reagent in their respective redox chemistries. Only the DMF-driven synthesis proved readily adaptable to the substrate-based platform but nanostar-like structures emerged from the other protocols when synthetic controls such as reaction kinetics, the addition of Ag(+)ions, and pH adjustments were applied. Because the nanostars were derived from near-hemispherical seeds, they acquired a unique geometry that resembles a conventional nanostar that has been truncated near its midsection. Simulations of plasmonic properties of this geometry reveal that such structures can exhibit maximum near-field intensities that are as much as seven-times greater than the standard nanostar geometry, a finding that is corroborated by surface-enhanced Raman scattering (SERS) measurements showing large enhancement factors. The study adds nanostars to the library of nanostructure geometries that are amenable to large-area periodic arrays and provides a potential pathway for the nanofabrication of SERS substrates with even greater enhancements.