Institute of Physical Chemistry and Abbe Center of Photonics , Friedrich Schiller University Jena , Helmholtzweg 4 , 07743 Jena , Germany.
Centre for Applied Research , InfectoGnostics Research Campus Jena , Philosophenweg 7 , 07743 Jena , Germany.
Anal Chem. 2018 Aug 7;90(15):9025-9032. doi: 10.1021/acs.analchem.8b01234. Epub 2018 Jul 23.
Raman spectroscopy in combination with appropriate sample preparation strategies, for example, enrichment of bacteria on metal surfaces, has been proven to be a promising approach for rapidly diagnosing infectious diseases. Unfortunately, the fabrication of the required chip substrates is usually very challenging due to the lack of feasible instruments that can be used for quality control in the surface modification process. The intrinsically weak Raman signal of the biomolecules, employed for the enrichment of the micro-organisms on the chip surface, does not allow for monitoring of the successful immobilization by means of a Raman spectroscopic approach. Within this contribution, we demonstrate how a simple modification of a plain aluminum surface enables enhancement (or a decrease, if desired) of the Raman signal of molecules deposited on that surface. The manipulation of the Raman signal strength is achieved via exploiting interference effects that occur, if the highly reflective aluminum surface is modified with thin layers of transparent dielectrics like aluminum oxide. The thicknesses of these layers were determined by theoretical considerations and calculations. For the first time, it is shown that the interference effects can be used for the detection of biomolecules as well by investigating the siderophore ferrioxamine B. The observed degree of enhancement was approximately 1 order of magnitude. Moreover, the employed aluminum/aluminum oxide layers have been thoroughly characterized using atomic force and scanning electron microscopy as well as X-ray reflectometry and UV-Vis measurements.
拉曼光谱结合适当的样品制备策略，例如在金属表面富集细菌，已被证明是一种快速诊断传染病的有前途的方法。不幸的是，由于缺乏可行的仪器来对表面修饰过程进行质量控制，所需的芯片衬底的制造通常极具挑战性。用于在芯片表面上富集微生物的生物分子的本征弱拉曼信号不允许通过拉曼光谱方法监测成功的固定化。在本研究中，我们展示了如何通过简单地修饰普通的铝表面来增强（如果需要，也可以减少）沉积在该表面上的分子的拉曼信号。通过利用如果高度反射的铝表面用透明电介质（如氧化铝）的薄层进行修饰时会发生的干涉效应来实现对拉曼信号强度的操纵。这些层的厚度是通过理论考虑和计算确定的。首次通过研究铁载体腐胺 B 表明，干涉效应也可用于检测生物分子。观察到的增强程度约为 1 个数量级。此外，使用原子力和扫描电子显微镜以及 X 射线反射率和紫外可见测量对所采用的铝/氧化铝层进行了彻底的表征。
