Figure 1

Three potential methods by which combined single-molecule force and fluorescence measurements can probe biomolecular interactions. (a) An optical trap; (b) dual optical traps; (c) an atomic force microscope (AFM). Labeling of a biomolecule, anchoring to a fixed surface and excitation using evanescent-wave illumination – that is, total internal reflection fluorescence (TIRF) microscopy – permit the simultaneous detection of single-molecule fluorescence and force.