Institut für Physikalische Chemie, Friedrich-Schiller-Universität Jena, Helmholtzweg 4, D-07743 Jena, Germany.
Analyst. 2009 Jun;134(6):1126-32. doi: 10.1039/b821705j. Epub 2009 Apr 9.
Resonance Raman spectroscopy was applied for investigating the malaria pigment hemozoin, which is an important target structure of antimalarial drugs. Morphology-sensitive low wavenumber modes of hemozoin were selectively enhanced with help of excitation wavelengths at lambda = 633 nm and lambda = 647 nm. The assignment of the most prominent bands in the Raman spectra at 343 cm(-1) and 368 cm(-1) was assisted by DFT calculations of the hemozoin dimer. The mode at 343 cm(-1) in the Raman spectrum of hemozoin is strongly enhanced with lambda(exc.) = 647 nm and is represented by a combined, symmetric doming mode of the two hematin units in the hemozoin dimer. The enhancement of this vibration is stronger in the resonance Raman spectrum of hemozoin compared with less crystalline beta-hematin. The selective resonance enhancement of the morphology-sensitive Raman modes of hemozoin is caused by absorption bands in the UV-VIS-NIR spectrum. This absorption spectrum of the crystalline malaria pigment hemozoin shows a strong band at 655 nm. Another broad absorption band at 870 nm is the reason for the strong relative resonance enhancement of the mode at 1372 cm(-1) in the Raman spectrum of crystalline hemozoin with lambda(exc.) = 830 nm. In conclusion, resonance Raman micro-spectroscopy with lambda(exc.) = 647 nm was shown to have great potential as an analytical tool to probe the morphology of hematin samples.
共振拉曼光谱被应用于研究疟色素血晶朊，它是抗疟药物的一个重要靶标结构。借助于 633nm 和 647nm 的激发波长，血晶朊的形态敏感低波数模式得到了选择性增强。在 343cm(-1) 和 368cm(-1) 处的拉曼光谱中最显著带的分配通过对血晶朊二聚体的 DFT 计算得到了辅助。在血晶朊的拉曼光谱中，343cm(-1)处的模式在 lambda(exc.) = 647nm 时被强烈增强，由血晶朊二聚体中两个血红素单元的对称穹顶模式共同表示。与非晶态β-血红素相比，该振动在血晶朊的共振拉曼光谱中的增强更强。血晶朊形态敏感拉曼模式的选择性共振增强是由 UV-VIS-NIR 光谱中的吸收带引起的。这种结晶疟色素血晶朊的吸收光谱在 655nm 处显示出一个强带。另一个在 870nm 处的宽吸收带是导致在 lambda(exc.) = 830nm 时在结晶血晶朊的拉曼光谱中 1372cm(-1)处的模式的相对共振增强很强的原因。总之，lambda(exc.) = 647nm 的共振拉曼微光谱被证明是一种很有潜力的分析工具，可以探测血红素样品的形态。
