October 1, 2007

NSLS Receives NIH Grant for a New Infrared Imaging Microscope

The NSLS has received a Shared Instrumentation Grant from National Institutes of Health (NIH) for $296,000 to purchase a state-of-the-art infrared imaging microscope system – a new endstation that will soon add new capabilities to the facility’s infrared programs. The Bruker Vertex 80v Fourier transform infrared (FTIR) spectrometer and Hyperion 3000 Imaging Microscope will be uniquely coupled to the synchrotron IR source to allow for faster data collection and improved spatial resolution for numerous studies.

In the life sciences, infrared imaging probes the molecular chemistry of biological cells and tissues, which is strongly affected by the process of disease. With the high brightness of synchrotron light, individual cells within a tissue or cell culture can be probed with sub-cellular resolution. Since the technique does not rely on stains or labels, it can be applied toward understanding a wide range of diseases, including plaque formation in Alzheimer’s disease, bone brittleness in osteoporosis, scar tissue formation in heart disease, and tumor growth in cancer.

Figure 1. (A) Bright field visible image of a human oral mucosa cell. (B) Synchrotron FPA image of the protein (Amide I) absorbance in the oral mucosa cell. The sample was illuminated with a low magnification objective (36X, 0.6 NA) for long working distance and collected with a high magnification (74X, 0.6 NA) objective. A 64x64 pixel MCT FPA detector was used to image the cell, where the resulting field of view on the FPA was 35x35 m with 0.54 m per pixel. The IR image (192x192 pixels) was generated in 72 minutes (200 scans, 6 cm-1 resolution). Scale bar is 20 m.

In a Fourier transform infrared microspectroscopy (FTIRM) experiment, an aperture confines the beam to the sample’s area of interest and a second aperture is used after the sample to define the region being sensed by the single-pixel IR detector. Currently, most synchrotron IR microscopes operate in the FTIRM configuration; however, data collection is time-consuming because single-element IR detectors are used. Images of just one biological cell can take more than an hour to collect, and subcellular imaging of significant regions of tissue can take several days.

The Hyperion 3000 microscope has a 128x128 pixel focal point array (FPA) detector so that “full-field” Fourier transform infrared imaging (FTIRI) can be performed. The instrument was tested at NSLS Beamline U10 with a customized set of optics designed by NSLS physicist, Larry Carr. With this configuration, the pixel resolution was 0.54 µm and an oral mucosa cell was imaged in 72 minutes (Figure 1). A conventional synchrotron IR microscope would have taken 25 days to collect at this pixel resolution. The high quality of synchrotron IR data, resulting from the brightness of the source, may allow one to mathematically correct for diffraction effects and improve the spatial resolution of FTIRI over regions of modest size. With the synchrotron, it’s anticipated that the resolution limit may be extended down to about 1 m.

The Hyperion 3000 is much needed for the users of the NSLS infrared imaging programs. For example, the program at U10B is currently 2-fold oversubscribed, despite offering 75% of its time to General Users. Beamlines U2A and U2B are also fully subscribed. While current IR users have been highly productive, it is expected that the FTIRI microscope will dramatically increase user access, improve productivity, and enable experiments that are not feasible with the current instrumentation.

The new FTIRI system is expected to arrive in October of 2007 and will be commissioned at Beamline U4IR. It should be available for general users beginning in the spring of 2008.

ARTICLE BY: Lisa Miller