Biological Applications of Scanning Tunneling Microscopy

The scanning tunneling microscope (STM) is a new and exciting method of direct surface analysis. Following the microscope’s first construction by Binnig and Rohrer in 1982 (1 ,2 )—for which they won the 1986 Nobel Prize for Physics—the instrument has been extensively used to investigate the surface properties of many inorganic conducting materials. In recent years, the microscope has been utilized to investigate biological molecules deposited on suitable conducting surfaces, providing atomic resolution images of single molecules, with no conformational averaging as occurs for spectroscopic techniques associated with the study of bulk molecules. These studies show that the technique is a potentially valuable biophysical tool complementary to the other well established methods that are extensively reviewed in this volume. To date, high resolution images of biological systems, such as DNA (3 ), globular macromolecules, such as vicilin (4 ), and phospholipid membranes (5 ) have been obtained, with the body of scientific literature increasing rapidly with time. This chapter reports on the basis of the use of the technique for imaging biologicals, the equipment required, and how STM imaging is undertaken.