Department of Chemistry, Lehigh University, 6 E. Packer Ave., Bethlehem, Pennsylvania 18015, United States.
Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States.
Anal Chem. 2022 Jan 18;94(2):1425-1431. doi: 10.1021/acs.analchem.1c04756. Epub 2021 Dec 28.
Peak force infrared (PFIR) microscopy achieves nanoscale infrared imaging at sub-10 nm spatial resolution through photothermal mechanical detection of atomic force microscopy (AFM). However, it suffers from a major limitation that only one infrared frequency can be scanned for an AFM frame at a time. To overcome this limitation, we report here dual-color PFIR microscopy that enables simultaneous imaging at two infrared frequencies. This dual-color PFIR microscopy bypasses the limitations of frame drift and distortion of AFM when comparing two images of different infrared frequencies. We benchmark the performance and spatial resolution of this method using structured polymers exhibiting phase separation. We further demonstrate the application of this technique in imaging biological samples by mapping the cell wall of () bacteria. The presence of a bacterial outer membrane was detected without extrinsic labels. This dual-color PFIR microscopy enables simultaneous nondestructive chemical nanoimaging of multiple chemical components and will be useful for potential applications such as dual-channel monitoring of chemical reactions.
峰值力红外（PFIR）显微镜通过原子力显微镜（AFM）的光热机械检测实现了亚 10nm 空间分辨率的纳米级红外成像。然而，它存在一个主要的局限性，即每次 AFM 帧只能扫描一个红外频率。为了克服这一限制，我们在这里报告了双色 PFIR 显微镜，它能够同时在两个红外频率下进行成像。这种双色 PFIR 显微镜在比较两个不同红外频率的图像时，避免了 AFM 图像漂移和失真的限制。我们使用表现出相分离的结构化聚合物来基准该方法的性能和空间分辨率。我们进一步通过绘制 () 细菌的细胞壁来展示该技术在生物样本成像中的应用。无需外部分子标记即可检测到细菌外膜的存在。这种双色 PFIR 显微镜能够同时对多个化学组分进行非破坏性的化学纳米成像，对于化学反应的双通道监测等潜在应用将非常有用。
