Focused Ion Beam techniques for the analysis of biological samples: a revolution in ultramicroscopy?

Focused ion Beam (FIB) is a novel technique that allows easy target cell selection, fast operation, high resolution, 3D imaging and sample manipulation during imaging. The FIB technique of microscopy and nanomachining, that is widely spread in semiconductor technology, is reshuffled to open new horizons in the field of life sciences at cellular and subcellular level. FIB is a source of ions which can be precisely oriented and focused on the sample, supported also by an electron source. The resolution can be as low as 15 nm. Two different operation modes are available: "cutting" and "etching" operations of very high precision and at the same time the resulting secondary ions and electrons provide follow up sample imaging. FIB tomography ability has been tested to provide information on cell characterisation, cell division time sequence, view of inner structures and investigation of membrane structural properties. We compare the performances and the advantages of different high-resolution microscopy techniques: Soft X-ray Contact Microscopy (SXCM), Focused Ion Beam (FIB) and Transmission Electron Microscopy (TEM). These have been used to image Saccharomyces cerevisiae yeast cells, a rather well known sample of great biological interest. TEM is an established technique used as a benchmark for comparison.