Department of Life Science , University of Seoul , 163 Siripdae-ro , Dongdaemun-gu, Seoul 02504 , Republic of Korea.
Department of Chemical Engineering , Konkuk University , Seoul , 05029 , South Korea.
Anal Chem. 2018 Apr 17;90(8):5023-5031. doi: 10.1021/acs.analchem.7b04674. Epub 2018 Apr 4.
Surface-enhanced Raman scattering (SERS) has recently been considered as one of the most promising tools to directly analyze small molecules without labels, owing to advantages in sensitivity, specificity, and speed. However, collecting reproducible SERS signals from small molecules on substrates or in solutions is challenging because of random molecular adsorption on surfaces and laser-induced molecular convection in solutions. Herein, we report a novel and efficient way to collect SERS signals from solution samples using three-dimensional nanoplasmonic wells spontaneously formed by interfacial reactions between liquid polydimethylsiloxane (PDMS) and small droplets of metal ion solutions (e.g., HAuCl and AgNO). A SERS signal is easily maximized at the center near the bottom of the well due to spherical feature of the fabricated wells and electromagnetic field enhancement by the metallic nanoparticles (e.g., Au and Ag) integrated on their surfaces. Through the systematic control over the volume, concentration, and composition of the metal ion solution, optical functions of the nanoplasmonic wells were optimized for SERS, which was further amplified by exploiting the plasmonic couplings with colloidal nanoparticles. By using the optimized nanoplasmonic wells and the detection protocol, we successfully obtained intrinsic spectra of biomolecules (e.g., adenine, glucose, amyloid β) and toxic environmental molecules (e.g., 1,1'-diethyl-2,2'-cyanine iodide and chloromethyliothiazolinone/methylisothiazolinone) as well as Raman active molecules, such as rhodamine 6G and 1,2-bis(4-pyridyl)ethylene at a low concentrations down to the picomolar level. Our detection platform provides a powerful way to develop highly sensitive sensors and high-throughput analyzing protocols for fieldwork applications as well as diagnosing diseases.
表面增强拉曼散射（SERS）最近被认为是一种最有前途的工具，可以在无需标记的情况下直接分析小分子，因为其具有灵敏度、特异性和速度方面的优势。然而，由于表面上的随机分子吸附和溶液中的激光诱导分子对流，从小分子在基底或溶液中收集重现性的 SERS 信号是具有挑战性的。在此，我们报道了一种从溶液样品中收集 SERS 信号的新颖且有效的方法，该方法使用液体聚二甲基硅氧烷（PDMS）与金属离子溶液（例如 HAuCl 和 AgNO）小液滴之间的界面反应自发形成的三维纳米等离子体井。由于所制造的井的球形特征和表面上集成的金属纳米粒子（例如 Au 和 Ag）的电磁场增强，很容易在井底部附近的中心处最大化 SERS 信号。通过系统地控制金属离子溶液的体积、浓度和组成，优化了纳米等离子体井的光学功能，通过与胶体纳米粒子的等离子体耦合进一步放大了该功能。通过使用优化的纳米等离子体井和检测方案，我们成功地获得了生物分子（例如腺嘌呤、葡萄糖、淀粉样 β）和有毒环境分子（例如 1,1'-二乙基-2,2'-氰化碘和氯甲基异噻唑啉酮/甲基异噻唑啉酮）以及拉曼活性分子（例如罗丹明 6G 和 1,2-双（4-吡啶基）乙烯）的本征光谱，其浓度低至皮摩尔级。我们的检测平台为开发用于现场应用以及诊断疾病的高灵敏度传感器和高通量分析协议提供了一种强大的方法。
