New and unconventional approaches for advancing resolution in biological transmission electron microscopy by improving macromolecular specimen preparation and preservation

Resolution in transmission electron microscopy (TEM) now is limited by the properties of specimens, rather than by those of instrumentation. The long-standing difficulties in obtaining truly high-resolution structure from biological macromolecules with TEM demand the development, testing, and application of new ideas and unconventional approaches. This review concisely describes some new concepts and innovative methodologies for TEM that deal with unsolved problems in the preparation and preservation of macromolecular specimens. The selected topics include use of better support films, a more protective multi-component matrix surrounding specimens for cryo-TEM and negative staining, and, several quite different changes in microscopy and micrography that should decrease the effects of electron radiation damage; all these practical approaches are non-traditional, but have promise to advance resolution for specimens of biological macromolecules beyond its present level of 3–10 Å (0.3–1.0 nm). The result of achieving truly high resolution will be a fulfillment of the still unrealized potential of transmission electron microscopy for directly revealing the structure of biological macromolecules down to the atomic level.