Femtogram Near-field Infrared Spectrometer for Biological Systems

生物系统Femtogram近场红外光谱仪生物分子，如蛋白质、核酸和脂类，可以用红外光谱进行研究。红外光谱中的峰是由分子本身的化学结构引起的。分子中化学基团的性质通常可以通过其红外光谱来识别。这种光谱也可以作为指纹。红外显微光谱技术将红外光谱技术与高分辨率成像技术相结合。因为这项技术利用了分子的固有性质，所以可以在不使用放射性或荧光标记的情况下获得图像的对比度。红外显微镜的一个传统缺点是，由于涉及的波长较长(与可见光相比)，空间分辨率较差。近场技术的使用使克服衍射极限成为可能，并使研究水中亚微米尺寸的样品成为可能。在国家科学基金的支持下，一种能够获取生物水样红外光谱的台式成像光谱仪正在开发中。光谱仪将按照与原子力显微镜相同的一般原理建造。在这个基本设计的基础上，将增加一个可调红外激光器和红外收集光学元件。由此产生的显微镜将是独一无二的，因为它允许在水下进行红外成像。一旦完成，将使用红外辐射检查单个活细胞。红外光谱仪的开发将为研究单个活细胞提供一个新的窗口，而不需要使用放射性或荧光染色。放射性标记非常敏感，但为了避免环境问题，样品必须小心处理和处置。许多荧光标记是致癌的，可能会扰乱被染色的细胞。除了允许对单个活细胞进行成像外，近场红外光谱仪还有可能根据细菌的特征红外特征识别细菌的类型。如果这一应用成功，该仪器将为检测病原菌提供一种方便的方法。

ABSTRACT9987157Shyamsunder ErramilliBoston UniversityFemtogram Near-field Infrared Spectrometer for Biological Systems Biological molecules like proteins, nucleic acids, and lipids can be studied using infrared spectroscopy. The peaks in an infrared spectrum are caused by the chemical structure of the molecules themselves. The nature of the chemical groups in a molecule can often be recognized by its infrared spectrum. That spectrum can also serve as a fingerprint. Infrared microspectroscopy combines infrared spectroscopy with high-resolution imaging. Because the technique uses an intrinsic property of the molecules, it is possible to get contrast in images without using radioactive or fluorescent labels. One traditional shortcoming of infrared microscopy is that the spatial resolution is poor, due to the longer wavelengths involved (compared to visible light). The use of near-field techniques makes it possible to overcome the diffraction limit and permits the study of sub-micron size samples in water. With support from the National Science Foundation, a table-top imaging spectrometer capable of acquiring the infrared spectrum of an aqueous biological sample is being developed. The spectrometer will be built along the same general principles as an atomic force microscope. To this basic design a tunable infrared laser and infrared collecting optics will be added. The resulting microscope will be unique in that it allows for infrared imaging under water. Once it is complete, single living cells will be examined using infrared radiation. Development of the infrared spectrometer will provide a new window to study single living cells without requiring the use of either radioactive or fluorescent stains. Radioactive labeling is very sensitive, but the samples have to be handled and disposed of carefully, in order to avoid environmental problems. Many fluorescent labels are carcinogenic, and may perturb the cells that are being stained. In addition to allowing the imaging of single living cells, the near-field infrared spectrometer has the potential to identify the type of bacteria from its characteristic infrared signature. If this application is successful, the instrument would provide a convenient method to detect pathogenic bacteria.