Department of Chemistry and Biochemistry, Wilfrid Laurier University, 75 University Avenue W, Waterloo, Ontario, Canada N2L 3C5.
Centre for Nanostructure Imaging, Department of Chemistry, University of Toronto, 80 St. George St. Rm. 50, Toronto M5S 3H6, Canada.
Nanoscale. 2016 Nov 3;8(43):18282-18290. doi: 10.1039/c6nr07397b.
In this work, we use silver decahedral nanoparticle (AgDeNP) seeds to synthesize pentagonal silver stars (AgStDeNPs) and study the sensing properties of these nanoparticles. The regrowth process of AgStDeNPs is kinetically-controlled, so the purity of the seed NPs is critical to avoid secondary deposition in the highly non-equilibrium reduction. To control the regrowth process, surface blocking with sodium polyacrylate (PANa) was implemented. PANa moderates rough silver nanostructures typically obtained by reduction with ascorbic acid. To modulate polymer binding to the surface and thus to tune surface blocking, pH served as a key synthetic parameter. Under optimal regrowth conditions, new sliver was deposited on the highest energy sites of the decahedra - the vertices of the rims - to yield pentagonal stars. The universality of this regrowth process was established with several different seed particles. The sharpness and size of the stellated tips are tunable by the amount of added silver. Gold deposition onto AgStDeNPs enables the preparation of diverse structures with enhanced stability. Ease of transformation, e.g. rounding, of star branches opens a promising venue for enhanced SPR sensing. Also, AgStDeNPs enable femtomolar detection of 5,5-dithiobis(2-nitrobenzoic acid) in SERS.
在这项工作中，我们使用银十面体纳米颗粒（AgDeNP）种子来合成五角形银星（AgStDeNPs），并研究这些纳米颗粒的传感特性。AgStDeNPs 的再生过程是动力学控制的，因此种子 NPs 的纯度对于避免在高度非平衡还原过程中的二次沉积至关重要。为了控制再生过程，我们采用了聚丙烯酸钠（PANa）进行表面封锁。PANa 缓和了通常通过抗坏血酸还原得到的粗糙银纳米结构。为了调节聚合物与表面的结合，从而调节表面封锁，pH 值作为一个关键的合成参数。在最佳的再生条件下，新的银沉积在十面体的高能点上——边缘的顶点——以生成五角星形。通过添加的银量可以调整五角星形的尖锐度和尺寸。金沉积到 AgStDeNPs 上可以制备具有增强稳定性的各种结构。通过改变星状分支的形状，例如变圆，可以为增强的 SPR 传感开辟一个有前景的途径。此外，AgStDeNPs 可以在 SERS 中检测到 5,5-二硫代双（2-硝基苯甲酸）的飞摩尔浓度。
