We show that laser-tweezers Raman spectroscopy of eukaryotic cells with a significantly larger diameter than the tight focus of a single beam laser trap leads to optical trapping of the cell by its optically densest part, i.e. typically the cell's nucleus. Raman spectra of individual optically trapped monocytes are compared with location-specific Raman spectra of monocytes adhered to a substrate. When the cell's nucleus is stained with a fluorescent live cell stain, the Raman spectrum of the DNA-specific stain is observed only in the nucleus of individual monocytes. Optically trapped monocytes display the same behavior. We also show that the Raman spectra of individual monocytes exhibit the characteristic Raman signature of cells that have not yet fully differentiated and that individual primary monocytes can be distinguished from transformed monocytes based on their Raman spectra. This work provides further evidence that laser tweezers Raman spectroscopy of individual cells provides meaningful biochemical information in an entirely nondestructive fashion that permits discerning differences between cell types and cellular activity.

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单个单核细胞的拉曼光谱显示单核细胞的单光束光学捕获发生在它们的细胞核上

我们展示了真核细胞的激光镊子拉曼光谱，其直径明显大于单光束激光陷阱的紧密焦点，导致细胞被其光密部分（即通常是细胞核）光学捕获。将单个光学捕获的单核细胞的拉曼光谱与粘附在基质上的单核细胞的位置特异性拉曼光谱进行比较。当细胞核用荧光活细胞染料染色时，DNA 特异性染料的拉曼光谱只能在单个单核细胞的细胞核中观察到。光学捕获的单核细胞表现出相同的行为。我们还表明，单个单核细胞的拉曼光谱表现出尚未完全分化的细胞的特征拉曼特征，并且可以根据其拉曼光谱将单个原代单核细胞与转化的单核细胞区分开来。这项工作提供了进一步的证据，证明单个细胞的激光镊子拉曼光谱以完全无损的方式提供了有意义的生化信息，可以辨别细胞类型和细胞活动之间的差异。