State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
College of Science, Nanjing Forestry University, Nanjing 210037, China.
Nanoscale. 2019 Oct 28;11(40):18543-18549. doi: 10.1039/c9nr04032c. Epub 2019 Oct 9.
Attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is a powerful technique that provides structural and functional information during dynamic reactions in aqueous solutions. One existing limitation is the sensitivity to extract the signals of trace-level analytes from the background water in situ and in real time. Here, we proposed a novel ATR-SEIRAS platform that integrated a large-scale triangle gold antenna array onto a conventional ATR-IR platform to increase the sensitivity of this analytical technique. A square centimeter level well-ordered gold antenna array was fabricated onto an Si prism via nanosphere lithography. The size-dependent antenna array resonance had weak correlation with the incident polarization and antenna orientation, allowing antenna array-enhanced IR detection without the requirement of a microscope. In addition, the antenna resonance shift that occurred due to analyte adsorption-induced refractive index variation could be minimized benefiting from the high refractive index of Si (3.4). As a demonstration, we dynamically monitored the adsorption of the trace levels of proteins on top of the antenna array with a real signal enhancement factor larger than 300. Our platform opens an avenue to apply antenna array-enhanced IR spectroscopy in an aqueous environment measured via commercial IR instruments, which is extremely promising for the interfacial applications that require signal enhancement.
衰减全反射表面增强红外吸收光谱（ATR-SEIRAS）是一种强大的技术，可在水溶液中的动态反应过程中提供结构和功能信息。目前存在的一个限制是，从原位和实时的背景水中提取痕量分析物信号的灵敏度。在这里，我们提出了一种新颖的 ATR-SEIRAS 平台，即将大规模三角形金天线阵列集成到常规 ATR-IR 平台上，以提高该分析技术的灵敏度。通过纳米球光刻在 Si 棱镜上制造了一平方厘米级别的有序金天线阵列。尺寸相关的天线阵列共振与入射偏振和天线方向的相关性较弱，允许在无需显微镜的情况下进行天线阵列增强的红外检测。此外，由于分析物吸附诱导折射率变化引起的天线共振位移可以最小化，这得益于 Si（3.4）的高折射率。作为一个演示，我们动态监测了在天线阵列顶部的痕量蛋白质的吸附，实际信号增强因子大于 300。我们的平台为通过商业红外仪器在水相环境中应用天线阵列增强的红外光谱开辟了道路，这对于需要信号增强的界面应用极具前景。
