Urchin-shaped gold nanoparticles (AuNUs) are anisotropic nanomaterials with unique chemical and physical properties of interest for a variety of applications. However, synthesizing AuNUs with controlled sizes and shapes remains challenging. We demonstrate that a combination of sodium borohydride (NaBH₄) and ascorbic acid (AA) as reducing agents can produce an aqueous dispersion of AuNUs after just 9 min at room temperature (25 °C). The AuNUs were size- and shape-controlled using a molar ratio for NaBH₄/AA/HAuCl₄ = 1:1:1 at pH 3. The added aurate was almost entirely (98.8%) consumed in the formation of AuNUs. The resultant AuNU concentration was 1.1 × 10¹⁰ particles/mL. The diameters observed in transmission electron microscopy were 145.1 ± 37.4 nm. The AuNUs had an average of 12 spikes and an average volume of 3.7 × 10⁵ nm³. The partition volume between the spikes and the core of particles was 3:2. The AuNUs had a pink color and exhibited an absorption wavelength maximum at 540 nm. It is assumed that the AuNUs originate from icosahedral seeds and urchin shapes emerge from connecting smaller-sized seeds and larger-sized core particles.

中文翻译：

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通过使用混合硼氢化钠和抗坏血酸还原剂系统控制形状和尺寸制造金纳米海胆

海胆形金纳米粒子 (AuNU) 是各向异性纳米材料，具有独特的化学和物理特性，可用于各种应用。然而，合成具有受控尺寸和形状的 AuNU 仍然具有挑战性。我们证明硼氢化钠 (NaBH ₄ ) 和抗坏血酸 (AA) 作为还原剂的组合可以在室温 (25 °C) 下仅 9 分钟后产生 AuNU 的水分散体。在 pH 3 时，使用 NaBH ₄ /AA/HAuCl ₄ = 1:1:1的摩尔比对 AuNU 进行尺寸和形状控制。添加的金酸盐几乎完全 (98.8%) 在 AuNU 的形成过程中被消耗掉。得到的 AuNU 浓度为 1.1 × 10 ¹⁰颗粒/毫升。在透射电子显微镜中观察到的直径为 145.1 ± 37.4 nm。AuNU 平均有 12 个尖峰，平均体积为 3.7 × 10 ⁵ nm ³。尖峰与颗粒核心之间的分配体积为 3:2。AuNU 呈粉红色，在 540 nm 处表现出最大吸收波长。假设 AuNU 源自二十面体种子，而海胆形状则是通过连接较小尺寸的种子和较大尺寸的核心颗粒而出现的。