4 - Making the invisible visible: part 2 – without visible light

Summary

Seeing is Believing.

(Manfred Von Heimendahl in Electron Microscopy of Materials: an Introduction, 1981. © Elsevier)

GENERAL IDEA

Here we discuss the miscellaneous experimental techniques that allow us to monitor single biological molecules using physical approaches which do not rely primarily on visible light.

Introduction

There now exist several methods which permit measurement of the presence of single biological molecules using physical principles which do not rely primarily on the detection of visible light. These include a variety of scanning probe microscopy techniques, including atomic force microscopy, which are discussed in detail in the first section of this chapter. In addition, significant advances in our understanding of single-molecule biology have come from methods using electron microscopy, which is one of the pioneering techniques used for obtaining structural information on fixed single-molecule samples. Recent advances in the measurement of small ion currents through both solid-state and native physiological nanometre length scale pores have furthered our knowledge of many areas of single-molecule bioscience. Furthermore, Raman spectroscopy has now advanced to a level of sensitivity such that measurements of single biological molecules are feasible. And finally, there are several microscopy methods which allow us to deduce the position of single molecules using primarily infrared optical tweezers.