Departamento de Química Física and Unidad Asociada CSIC-Universidade de Vigo, 36310 Vigo, Spain.
Langmuir. 2010 Sep 21;26(18):14943-50. doi: 10.1021/la102559e.
Gold nanostars are multibranched nanoparticles with sharp tips, which display extremely interesting plasmonic properties but require optimization. We present a systematic investigation of the influence of different parameters on the size, morphology, and monodispersity of Au nanostars obtained via seeded growth in concentrated solutions of poly(vinylpyrrolidone) in N,N-dimethylformamide. Controlled prereduction of Au(3+) to Au(+) was found to influence monodispersity (narrower plasmon bands), while the [HAuCl(4)]/[seed] molar ratio significantly affects the morphology and tip plasmon resonance frequency. We also varied the size of the seeds (2-30 nm) and found a clear influence on the final nanostar dimensions as well as on the number of spikes, while synthesis temperature notably affects the morphology of the particles, with more rounded morphologies formed above 60 °C. This rounding effect allowed us to confirm the importance of sharp tips on the optical enhancing behavior of these nanoparticles in surface-enhanced raman scattering (SERS). Additionally, the sensitivity toward changes in the local refractive index was found to increase for larger nanostars, though lower figure of merit (FOM) values were obtained because of the larger polydispersity.
金纳米星是具有尖锐尖端的多分支纳米粒子，具有非常有趣的等离子体特性，但需要进行优化。我们系统地研究了不同参数对在 N,N-二甲基甲酰胺中聚（N-乙烯基吡咯烷酮）的浓缩溶液中通过种子生长获得的 Au 纳米星的尺寸、形态和单分散性的影响。受控的 Au(3+)预还原被发现会影响单分散性（更窄的等离子体带），而 [HAuCl(4)]/[种子]摩尔比则显著影响形态和尖端等离子体共振频率。我们还改变了种子的尺寸（2-30nm），发现它们对最终纳米星的尺寸以及刺的数量有明显的影响，而合成温度显著影响颗粒的形态，高于 60°C 时形成更圆的形态。这种变圆效应使我们能够确认在表面增强拉曼散射（SERS）中这些纳米粒子的尖锐尖端对光学增强行为的重要性。此外，发现较大的纳米星对局部折射率变化的敏感性增加，但由于较大的多分散性，获得的品质因数（FOM）值较低。
