Gold nanorods (GNRs) as plasmonic metal nanoparticles are valuable for optical applications due to their tunable plasmonic properties. However, conventional colloidal GNRs face significant optical instability during storage, which limits their practical use. In this work, we developed a highly dispersible GNR powder using an octadecyl trimethylammonium bromide (C₁₈TAB)-assisted freeze-drying method, preserving the optical and chemical sensing properties of GNRs for over 4 months. Compared with C₁₆TAB, C₁₈TAB significantly enhances the GNRs dispersibility even at lower concentrations. Our study demonstrates that C₁₈TAB forms a sponge-like crystal structure that prevents aggregation during the freeze-drying process. The resulting GNR powder retains its plasmonic features and water dispersibility, achieving near-identical optical properties to those of fresh GNR solutions. This stability enabled creation of a liquid-free colorimetric test kit with a long shelf life. This work marks a significant step forward in the use of GNRs as standard analytical reagents, opening new avenues for real-world applications.

中文翻译：

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用于光学传感器的高度单分散稳定金纳米棒粉末


金纳米棒 （GNR） 作为等离子体金属纳米颗粒，由于其可调等离子体特性，在光学应用中很有价值。然而，传统的胶体 GNR 在储存过程中面临明显的光学不稳定性，这限制了它们的实际使用。在这项工作中，我们使用十八烷基三甲基溴化铵 （C₁₈TAB） 辅助冷冻干燥方法开发了一种高度分散的 GNR 粉末，将 GNR 的光学和化学传感特性保持 4 个月以上。与 C₁₆TAB 相比，即使在较低浓度下，C₁₈TAB 也能显著提高 GNR 的分散性。我们的研究表明，C₁₈TAB 形成海绵状晶体结构，可防止冷冻干燥过程中聚集。所得的 GNR 粉末保留了其等离子体特性和水分散性，实现了与新鲜 GNR 溶液几乎相同的光学特性。这种稳定性使创建具有较长保质期的无液体比色检测试剂盒成为可能。这项工作标志着使用 GNR 作为标准分析试剂向前迈出了重要一步，为实际应用开辟了新的途径。