School of Materials Science and Engineering, State Key Laboratory for Power Metallurgy , Central South University , Changsha , Hunan 410083 , China.
China Academy of Engineering Physics , Mianyang 621900 , China.
Inorg Chem. 2018 Jul 16;57(14):8599-8607. doi: 10.1021/acs.inorgchem.8b01354. Epub 2018 Jun 28.
Gold nanostars (GNSs) have received considerable attention in surface-enhanced spectroscopies, catalysis, biosensing, photothermal therapy, and photovoltaics because of their unique optical properties arising from the anisotropic structure. GNSs typically consisting of a central core and several protruding tips are usually synthesized by a seed-mediated growth approach, but the growth mechanism and optical properties have yet to be fully understood. Here, we systematically investigate the seed-mediated growth process of GNSs to gain an insight into the growth mechanism and evolution of their optical and photothermal properties. By tailoring the core size, tip length and tip angle, the main localized surface plasmon resonance (LSPR) peak wavelength can be broadly tuned from the visible to near-infrared (NIR) region. Our observations show that the protruding tips grow rapidly away from the central core at the initial growth stage, leading to a red-shift of the main LSPR peak. The preferential deposition of gold atoms onto the gold core takes place at the later growth stage, gradually blue-shifting the main LSPR peak. GNSs exhibit a large molar extinction coefficient ranging from 4.0 × 10 M cm to 4.5 × 10 M cm, the log value of which correlates linearly with the main LSPR peak wavelength and accordingly allows for facile determination of the GNS concentration in a suspension. In addition, GNSs are excellent NIR photothermal materials with the LSPR-dependent photothermal conversion efficiency. The maximum photothermal conversion efficiency of GNSs occurs at a LSPR wavelength of 740 nm, blue-shifted from the incident laser wavelength. Our present work suggests that GNSs exhibit excellent optical and photothermal properties that can be optimized by tailoring the dimensional parameters.
金纳米星（GNSs）由于其各向异性结构引起的独特光学性质，在表面增强光谱学、催化、生物传感、光热疗法和光电领域受到了广泛关注。GNSs 通常由一个中心核和几个突出的尖端组成，通常通过种子介导的生长方法合成，但生长机制和光学性质尚未完全理解。在这里，我们系统地研究了 GNSs 的种子介导生长过程，以深入了解其生长机制以及光学和光热性质的演变。通过调整核尺寸、尖端长度和尖端角度，可以将主要局域表面等离子体共振（LSPR）峰波长从可见光宽调到近红外（NIR）区域。我们的观察表明，在初始生长阶段，突出的尖端从中心核快速生长，导致主要 LSPR 峰红移。在后期生长阶段，金原子优先沉积在金核上，导致主要 LSPR 峰逐渐蓝移。GNSs 表现出从 4.0×10 M cm 到 4.5×10 M cm 范围的大摩尔消光系数，其对数与主要 LSPR 峰波长线性相关，因此可以方便地确定悬浮液中 GNS 的浓度。此外，GNSs 是优异的近红外光热材料，具有与 LSPR 相关的光热转换效率。GNSs 的最大光热转换效率发生在 LSPR 波长为 740nm 处，从入射激光波长蓝移。我们的工作表明，GNSs 表现出优异的光学和光热性质，可以通过调整尺寸参数进行优化。
