BioNEM Laboratory, Experimental and Clinical Medicine Department, University "Magna Graecia" of Catanzaro, 88100 Loc. Germaneto, Catanzaro, Italy.
Analyst. 2013 Nov 12;138(24):7331-40. doi: 10.1039/c3an01665j.
The Raman spectra of biological materials always exhibit complex profiles, constituting several peaks and/or bands which arise due to the large variety of biomolecules. The extraction of quantitative information from these spectra is not a trivial task. While qualitative information can be retrieved from the changes in peaks frequencies or from the appearance/disappearance of some peaks, quantitative analysis requires an examination of peak intensities. Unfortunately in biological samples it is not easy to identify a reference peak for normalizing intensities, and this makes it very difficult to study the peak intensities. In the last decades a more refined mathematical tool, the extended multiplicative signal correction (EMSC), has been proposed for treating infrared spectra, which is also capable of providing quantitative information. From the mathematical and physical point of view, EMSC can also be applied to Raman spectra, as recently proposed. In this work the reliability of the EMSC procedure is tested by application to a well defined biological system: the 20 standard amino acids and their combination in peptides. The first step is the collection of a Raman database of these 20 amino acids, and subsequently EMSC processing is applied to retrieve quantitative information from amino acids mixtures and peptides. A critical review of the results is presented, showing that EMSC has to be carefully handled for complex biological systems.
生物材料的拉曼光谱通常呈现复杂的轮廓，由多种生物分子引起的多个峰和/或带组成。从这些光谱中提取定量信息不是一项简单的任务。虽然可以从峰频率的变化或某些峰的出现/消失中获取定性信息，但定量分析需要检查峰强度。不幸的是，在生物样品中，很难找到一个用于归一化强度的参考峰，这使得研究峰强度变得非常困难。在过去的几十年中，一种更精细的数学工具——扩展乘性信号校正（EMSC）被提出用于处理红外光谱，它也能够提供定量信息。从数学和物理的角度来看，正如最近提出的那样，EMSC 也可以应用于拉曼光谱。在这项工作中，通过应用于一个定义明确的生物系统——20 种标准氨基酸及其在肽中的组合，测试了 EMSC 程序的可靠性。第一步是收集这 20 种氨基酸的拉曼数据库，然后应用 EMSC 处理从氨基酸混合物和肽中检索定量信息。对结果进行了批判性评估，表明对于复杂的生物系统，必须小心处理 EMSC。
