About High Resolution Microscopy Techniques

The MicroXCT-200 is an x-ray transmission microscope that provides 3D tomograms based on contrast generated through x-ray attenuation. This bench top unit has a high spatial resolution (0.5μm) and can visualize internal structures of harvested tissues to see critical features or defects without cutting/sectioning specimens, that is, by keeping the specimens intact! A variety of specimens from rocks, insects, plants, softer and harder tissues, and other synthetic variants can be imaged using the MicroXCT-200.

The MicroXCT-200 complements high resolution imaging techniques such as, atomic force microscopy, and light microscopy techniques within the Division of Biomaterials and Bioengineering, and fosters newer opportunities through interdepartmental and campus wide collaborations.

This facility is also open to outside users within the UC systems, other universities, and companies.

The approximate operable energy range of this system is ~30kV-90kV, and the available magnifications are: 2X, 4X, 10X, 20X, and 40X

The UCSF Bioengineering and Biomaterials High Resolution Correlative Imaging Facility also houses the Sigma 500 scanning electron microscope. The Sigma 500 is a variable pressure system, with scanning electron, scanning transmission, and back scattered electron imaging modes.

Sigma 500 allows users to examine biological specimens without coating a conductive layer. Specimen preparation is straightforward and the variable pressure mode of the system allows non-invasive/less destructive imaging. The use of backscattered electrons helps differentiate components consisting of higher and lower atomic masses, and provides insights into elemental information within tissues.

In addition to the scanning mode, Sigma 500's transmission mode allows users to acquire images like a traditional transmission electron microscope (TEM). That is, internal structures of specimens prepared to image using TEM also can be revealed by STEM mode on the Sigma 500. While traditional TEM usually holds one grid, the STEM sample holder accommodates 12 grids and facilitates high throughput. The sample navigation facilitated by a camera will identify the region of interest for correlative imaging, using light and electron microscopy techniques on the same specimen. This system facilitates high throughput and enables multi-length scale correlation of data sets acquired from light and X-ray microscopy techniques.

The multiple length-scale correlation between cells, tissues and organs using this electron microscope is key to gaining insights into pathologies, and subsequently can lead to novel clinical interventions.

The Bioengineering and Biomaterials High Resolution Correlative Imaging Facility is directed by Dr. Sunita Ho and managed by Dr. Ling Chen. The instrument is housed on the eighth floor of Health Science West, 513 Parnassus Ave. and is open to all investigators at UCSF ($83/hour) and community at large through recharge.