Asymmetric seed passivation for regioselective overgrowth and formation of plasmonic nanobowls
Asymmetric seed passivation for regioselective overgrowth and formation of plasmonic nanobowls
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DOI：
10.1039/d2nr05182f
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发表时间：
2022-11-08
期刊：
影响因子：
6.7
通讯作者：
Skrabalak, Sara E.
中科院分区：
文献类型：
--
作者：
Woessner, Zachary J.;Lewis, George R.;Skrabalak, Sara E.
等离子体纳米粒子（NPs）由于其独特的光电特性在过去的几十年里引起了人们的兴奋，导致它们在各种传感应用和治疗中得到了应用。对称性决定了许多纳米材料的性质，而具有低对称性但仍有定义的纳米结构，与具有高对称性的纳米结构相比，往往表现出明显不同的性质。虽然有许多方法可以操纵对称性，但由于聚合物等表面保护基团能够实现NP种子的区域选择性修饰，可以在过度生长后去除，因此正在发现其用途。具体来说，聚苯乙烯-b-聚丙烯酸（PSPAA）通过与十六烷基三甲基溴化铵（CTAB）配体竞争来非对称钝化立方金种子。通过坍塌的PSPAA进行的不对称钝化导致在种子过度生长过程中，Au立方体只有选定的顶点和面可用于沉积新材料（即Au， Au- ag合金和Au- pd合金）。在低金属前体浓度下，沉积遵循未钝化种子的观察结果，但新材料仅从暴露的种子部分生长。在高金属前驱体浓度下，沉积相与钝化PSPAA相互作用形成纳米碗状结构。通过实验和模拟，研究了纳米碗的光电性能，发现表面增强拉曼光谱（SERS）显示纳米碗的内部和外部可以选择性地功能化。
Plasmonic nanoparticles (NPs) have garnered excitement over the past several decades stemming from their unique optoelectronic properties, leading to their use in various sensing applications and theranostics. Symmetry dictates the properties of many nanomaterials, and nanostructures with low, but still defined symmetries, often display markedly different properties compared to their higher symmetry counterparts. While numerous methods are available to manipulate symmetry, surface protecting groups such as polymers are finding use due to their ability to achieve regioselective modification of NP seeds, which can be removed after overgrowth as shown here. Specifically, poly(styrene-b-polyacrylic acid) (PSPAA) is used to asymmetrically passivate cubic Au seeds through competition with hexadecyltrimethylammonium bromide (CTAB) ligands. The asymmetric passivation via collapsed PSPAA causes only select vertices and faces of the Au cubes to be available for deposition of new material (i.e., Au, Au-Ag alloy, and Au-Pd alloy) during seeded overgrowth. At low metal precursor concentrations, deposition follows observations from unpassivated seeds but with new material growing from only the exposed seed portions. At high metal precursor concentrations, nanobowl-like structures form from interaction between the depositing phase and the passivating PSPAA. Through experiment and simulation, the optoelectronic properties of these nanobowls were probed, finding that the interiors and exteriors of the nanobowls can be functionalized selectively as revealed by surface enhanced Raman spectroscopy (SERS).