Department of Pure and Applied Chemistry, Technology and Innovation Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, UK.
Analyst. 2018 Dec 3;143(24):5965-5973. doi: 10.1039/c8an01249k.
The ability to probe through barriers and tissue non-invasively is an urgent unmet need in both the security and biomedical imaging fields. Surface enhanced Raman spectroscopy (SERS) has been shown to yield superior enhancement in signal over conventional Raman techniques. Furthermore, by utilising a resonant Raman reporter to produce surface enhanced resonance Raman spectroscopy (SERRS), even greater enhancement in chemical signal can be generated. Here we show the benefit of using red-shifted chalcogenpyrylium based Raman reporters for probing through large thicknesses of plastic and tissue barriers using a conventional Raman instrument. In addition, the benefit of using a resonant Raman reporter for superior levels of through barrier detection is demonstrated, and we aim to show the advantage of using resonant nanotags in combination with conventional Raman spectroscopy to probe through plastic and tissue barriers. Raman signals were collected from SERRS active nanotags through plastic thicknesses of up to 20 mm, as well as the detection of the same SERRS nanotags through up to 10 mm of tissue sections using a handheld conventional Raman spectrometer. The ability to detect SERRS-active nanotags taken up into ex vivo tumour models known as multicellular tumour spheroids (MTS), through depths of 5 mm of tissue is also shown. The advantages of applying multivariate analysis for through barrier detection when discriminating analytes with similar spectral features as the barrier is also clearly demonstrated. To the best of our knowledge, this is the first report of the assessment of the maximum level of through barrier detection using a conventional handheld Raman instrument for SERS applications as well as demonstration of the power of resonant nanotags for probing through barriers using conventional Raman spectroscopy.
在安全和生物医学成像领域，能够非侵入式地穿透障碍物和组织进行探测是一个迫切未满足的需求。表面增强拉曼光谱（SERS）已被证明在信号增强方面优于传统的拉曼技术。此外，通过利用共振拉曼报告物产生表面增强共振拉曼光谱（SERRS），可以产生更大的化学信号增强。在这里，我们展示了利用红移的硫属 pyrylium 基拉曼报告物在使用常规拉曼仪器穿透大厚度塑料和组织屏障时的优势。此外，还展示了使用共振拉曼报告物进行卓越的穿透屏障检测的优势，我们旨在展示在结合常规拉曼光谱穿透塑料和组织屏障时使用共振纳米标签的优势。从厚度高达 20 毫米的塑料中收集到 SERRS 活性纳米标签的拉曼信号，以及使用手持式常规拉曼光谱仪穿过 10 毫米厚的组织切片检测到相同的 SERRS 纳米标签的信号。还展示了通过 5 毫米厚的组织穿透已知为多细胞肿瘤球体（MTS）的体外肿瘤模型中摄取的 SERRS 活性纳米标签的检测能力。还清楚地证明了在通过屏障检测中应用多元分析来区分与屏障具有相似光谱特征的分析物的优势。据我们所知，这是首次评估使用常规手持式拉曼仪器进行 SERS 应用的穿透屏障检测的最大水平的报告，以及展示共振纳米标签在使用常规拉曼光谱穿透屏障时的强大功能。
