College of Optical and Electronic Technology, China Jiliang University, 310018 Hangzhou, China.
Chinese Academy of Inspection and Quarantine (CAIQ), No. A 3, Gaobeidian Road, Chaoyang District, Beijing 100123, China.
Langmuir. 2021 Jan 19;37(2):939-948. doi: 10.1021/acs.langmuir.0c03323. Epub 2021 Jan 4.
Controllable synthesis of novel metal nanoparticles and effective capture of hotspots are of great significance for SERS (surface-enhanced Raman spectroscopy) detection. Therefore, in this paper, a green controllable synthesis method of gold nanoparticle was achieved via epigallocatechin gallate reduction. Different morphologies of gold nanoparticles were synthesized just by changing the solution pH values, and the growth kinetics of AuNPs (gold nanoparticles) were systematically studied. The synthetic AuNPs were put in a droplet to study dynamic variations of self-assembly SERS hotspots from the liquid sol state to the solid dry state. The addition of halogen ions in the droplet can controllably regulate the self-assembly three-dimensional hotspot model of gold nanoparticles in the evaporation process of a droplet, during which the most enhancement effect can be easily captured. The dynamically changing images of nanoparticles in the process were graphically described based on the internal interaction forces of a droplet. Two stronger areas in the changes of SERS intensity were achieved with a high concentration of halogen ions, while only one maximum intensity area was obtained with a low concentration of halogen ions added. This method can effectively avoid complex and unpredictable microenvironments of SERS substrates in the liquid drop, further improving the reproducibility of SERS detection as well as broadening it to biological applications.
可控合成新型金属纳米粒子并有效捕获热点，对于 SERS（表面增强拉曼光谱）检测具有重要意义。因此，本文通过儿茶素没食子酸酯还原法实现了金纳米粒子的绿色可控合成。通过改变溶液 pH 值，可合成出不同形貌的金纳米粒子，并对 AuNPs（金纳米粒子）的生长动力学进行了系统研究。将合成的 AuNPs 放入液滴中，研究了自组装 SERS 热点从液态溶胶到固态干燥状态的动态变化。在液滴蒸发过程中，加入卤素离子可控制地调节金纳米粒子的自组装三维热点模型，在此过程中可以很容易地捕获到增强效果最佳的状态。基于液滴内部相互作用力，以图形方式描述了纳米粒子在过程中的动态变化。在高浓度卤素离子存在下，SERS 强度的变化出现了两个较强的区域，而在低浓度卤素离子存在下，只得到一个最大强度区域。该方法可以有效地避免液滴中 SERS 基底复杂且不可预测的微环境，进一步提高了 SERS 检测的重现性，并将其扩展到生物应用领域。
