Centre for Biospectroscopy, School of Chemistry, Monash University, 3800 Victoria, Australia.
Nano Lett. 2011 May 11;11(5):1868-73. doi: 10.1021/nl103004n. Epub 2011 Apr 12.
Tip-enhanced Raman scattering (TERS) is a powerful technique to obtain molecular information on a nanometer scale, however, the technique has been limited to cell surfaces, viruses, and isolated molecules. Here we show that TERS can be used to probe hemozoin crystals at less than 20 nm spatial resolution in the digestive vacuole of a sectioned malaria parasite-infected cell. The TERS spectra clearly show characteristic bands of hemozoin that can be correlated to a precise position on the crystal by comparison with the corresponding atomic force microscopy (AFM) image. These are the first recorded AFM images of hemozoin crystals inside malaria-infected cells and clearly show the hemozoin crystals protruding from the embedding medium. TERS spectra recorded of these crystals show spectral features consistent with a five-coordinate high-spin ferric heme complex, which include the electron density marker band ν(4) at 1373 cm(-1) and other porphyrin skeletal and ring breathing modes at approximately 1636, 1557, 1412, 1314, 1123, and 1066 cm(-1). These results demonstrate the potential of the AFM/TERS technique to obtain nanoscale molecular information within a sectioned single cell. We foresee this approach paving the way to a new independent drug screening modality for detection of drugs binding to the hemozoin surface within the digestive vacuole of the malaria trophozoite.
尖端增强拉曼散射（TERS）是一种在纳米尺度上获取分子信息的强大技术，但该技术仅限于细胞表面、病毒和分离的分子。在这里，我们展示了 TERS 可用于探测疟原虫感染细胞的消化液泡中小于 20nm 空间分辨率的血晶蛋白晶体。TERS 光谱清楚地显示了血晶蛋白的特征谱带，通过与相应的原子力显微镜（AFM）图像比较，可以将其与晶体上的精确位置相关联。这是首次在感染疟原虫的细胞内记录的 AFM 图像，清楚地显示了从包埋介质中突出的血晶蛋白晶体。对这些晶体记录的 TERS 光谱显示出与五配位高自旋铁血红素配合物一致的光谱特征，包括电子密度标记带 ν(4)在 1373cm(-1)和其他卟啉骨架和环呼吸模式约 1636、1557、1412、1314、1123 和 1066cm(-1)。这些结果表明 AFM/TERS 技术有可能在切片单个细胞内获得纳米尺度的分子信息。我们预计这种方法将为检测疟原虫滋养体消化液泡中与血晶蛋白表面结合的药物开辟一种新的独立药物筛选模式。
