Viruses are infections species that infect a large spectrum of living systems. Although displaying a wide variety of shapes and sizes, they are all composed of nucleic acid encapsulated into a protein capsid. After virions enter the host cell, they replicate to produce multiple copies of themselves. They then lyse the host, releasing virions to infect new cells. The high proliferation rate of viruses is the underlying cause of their fast transmission among living species. Although many viruses are harmless, some of them are responsible for severe diseases such as AIDS, viral hepatitis, and flu. Traditionally, electron microscopy is used to identify and characterize viruses. This approach is time- and labor-consuming, which is problematic upon pandemic proliferation of previously unknown viruses, such as H1N1 and COVID-19. Herein, we demonstrate a novel diagnosis approach for label-free identification and structural characterization of individual viruses that is based on a combination of nanoscale Raman and infrared spectroscopy. Using atomic force microscopy–infrared (AFM-IR) spectroscopy, we were able to probe structural organization of the virions of Herpes Simplex Type 1 viruses and bacteriophage MS2. We also showed that tip-enhanced Raman spectroscopy (TERS) could be used to reveal protein secondary structure and amino acid composition of the virus surface. Our results show that AFM-IR and TERS provide different but complementary information about the structure of complex biological specimens. This structural information can be used for fast and reliable identification of viruses. This nanoscale bimodal imaging approach can be also used to investigate the origin of viral polymorphism and study mechanisms of virion assembly.

中文翻译：

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使用原子力显微镜红外光谱（AFM-IR）和尖端增强拉曼光谱（TERS）对单个病毒颗粒进行纳米级结构表征。

病毒是感染多种生物的感染物种。尽管显示出各种各样的形状和大小，但它们都由包裹在蛋白质衣壳中的核酸组成。病毒体进入宿主细胞后，它们复制以产生自身的多个副本。然后，他们裂解宿主，释放病毒体以感染新细胞。病毒的高增殖率是其在活物种之间快速传播的根本原因。尽管许多病毒是无害的，但其中一些病毒可导致艾滋病，病毒性肝炎和流感等严重疾病。传统上，电子显微镜用于识别和表征病毒。这种方法既费时又费力，这对于以前未知的病毒（例如H1N1和COVID-19）的大流行扩散是有问题的。在这里 我们展示了一种基于纳米级拉曼光谱和红外光谱技术的无标签识别和单个病毒结构特征的新颖诊断方法。使用原子力显微镜-红外（AFM-IR）光谱，我们能够探测1型单纯疱疹病毒和MS2噬菌体的病毒的结构组织。我们还表明，可以使用尖端增强拉曼光谱（TERS）揭示病毒表面的蛋白质二级结构和氨基酸组成。我们的结果表明，AFM-IR和TERS提供了有关复杂生物标本结构的不同但互补的信息。该结构信息可用于快速可靠地识别病毒。