| Abstract |
Field emission gun scanning electron microscopy (FEG-SEM) is a type of microscopy capable of producing very high resolution images of the surface of a sample. It has a wide range of applications in biological and materials science in which researchers wish to visualise and analyse the surface of a sample over a wide range of magnifications. Field emmision gun scanning electron microscopy can be used to image over a large surface area, can be used to image bulk materials as well as thin films or spots and modern microscopes can image structures as small as one or two nanometres. Conventional FEG-SEM requires samples to be imaged under a high vacuum which means that specimens, for example biological materials which are wet, would produce a lot of vapour which interferes with the images. To visualise biological specimens by conventional FEG-SEM the specimens have to be dried and coated, which can distort images of structures. Another form of SEM, called environmental SEM (ESEM) allows samples to be visualised in low pressure gaseous environments and high humidity which means that biological samples can be imaged in their hydrated state either directly or in the frozen state. In this application we are seeking to replace a conventional SEM which is 27 years old, still requires film processing (does not acquire digital images) and frequently breaks down. We wish to purchase a versatile high resolution low-vacuum FEG-SEM and a cryo-workstation. The microscope is critically required for a large number of current and future projects in biological sciences, in particular research in tissue engineering, biomaterials, structural molecular and cellular biology. The microscope requested, is the most versatile high resolution feild emmision gun electron microscope available with extended low-vacuum capabilities. A major feature is that it does with a single tool, what used to require multiple systems. The scanning electron microscope has three modes of operation: high vacuum, low vacuum and environmental scanning (ESEM). The resolution achievable under different modes is 1-nanometres. The equipment will directly replace the old SEM in the current electron microscope unit in the Faculty of Biological Sciences. No refurbishment will be required. The use of the equipment will be supported by a Faculty funded full time technician. The microscope will be used to image a range of different specimens carried out by numerous researchers and postgraduate students. Examples of specimens that will be imaged include three dimensional collagenous scaffolds which are used in tissue engineering, cells adhering to and growing in tissue engineering scaffolds, nanoparticles produced by biomaterials used in hip and knee replacements, nanoparticles in body tissues and in environmental samples, virus particles, fibrils of proteins that cause disease such as amyloid and prion proteins and proteins that cause muscles to contract and bacteria to move. |
