Department of Industrial Chemistry, Tokyo University of Science , 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan.
Langmuir. 2013 Dec 3;29(48):15058-64. doi: 10.1021/la403431n. Epub 2013 Nov 20.
We propose a general strategy for fabricating ultrasmall attoliter-sized (10(-18) L) one-dimensional (1D) aligned nanocup arrays embedded in poly(dimethylsiloxane) (PDMS) films based on a combination of colloidal soft-lithography and wrinkle processing. The nanocup consists of a metallic shell (silver-single or double-layer silver/gold type) with a thickness of several tens of nanometers and whose diameter was ca. 500 nm and cavity depth was ca. 250 nm. First, monodisperse polystyrene (PS) colloids (d = 500 nm) were arranged onto a sinusoidally wrinkled PDMS substrate. Then, the colloid particle arrays were transferred onto another flat PDMS substrate, and a metal film was vacuum deposited over the array to form a nanostructured surface consisting of half-shell metal-coated colloid particle arrays. After the metal-coated PS array was gently transferred onto another soft PDMS substrate prepared by nonthermal curing, the attached films were thermally cured. After that, both films were carefully separated to selectively transfer the metal-coated PS particle arrays, since the metallic shell on the PS surface can adhere to the soft PDMS. Finally, the PS colloids were removed by plasma etching, leaving behind the 1D hemispherical metallic shells, called here the "metallic nanocup array structure". This structure was evaluated by performing atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy measurements. We further demonstrate chemical modification of the inner nanocup surface through construction of a self-assembled monolayer, and we also fill them with nanomaterials (silica nanoparticles) to demonstrate their application to size-selecting devices. The obtained metallic nanocup arrays could be components in a new class of chemical and/or biological nanoreactors with small reaction vessels, surface-enhanced Raman scattering (SERS)-based sensors, and size separators for nanoparticles.
我们提出了一种在聚二甲基硅氧烷（PDMS）薄膜中制造超小的皮升（10(-18) L）一维（1D）排列纳米杯阵列的通用策略，该策略基于胶体软光刻和褶皱处理的结合。纳米杯由厚度为几十纳米的金属壳（银单层或双层银/金类型）组成，直径约为 500nm，腔深约为 250nm。首先，将单分散聚苯乙烯（PS）胶体（d = 500nm）排列在正弦形褶皱的 PDMS 基底上。然后，将胶体粒子阵列转移到另一个平坦的 PDMS 基底上，并在阵列上真空沉积金属膜，形成由半壳金属涂覆胶体粒子阵列组成的纳米结构表面。在将金属涂覆的 PS 阵列轻轻转移到通过非热固化制备的另一个软 PDMS 基底上之后，将附着的薄膜进行热固化。之后，小心地将两个薄膜分离以选择性地转移金属涂覆的 PS 粒子阵列，因为 PS 表面上的金属壳可以粘附在软 PDMS 上。最后，通过等离子体蚀刻去除 PS 胶体，留下一维半球形金属壳，称为“金属纳米杯阵列结构”。通过原子力显微镜、扫描电子显微镜和 X 射线光电子能谱测量对该结构进行了评估。我们进一步通过构建自组装单层来修饰纳米杯的内表面，并填充纳米材料（二氧化硅纳米粒子）以展示其在尺寸选择器件中的应用。获得的金属纳米杯阵列可以成为具有小反应容器的新型化学和/或生物纳米反应器、基于表面增强拉曼散射（SERS）的传感器以及纳米颗粒尺寸分离器的组件。
