Biased Diffusion, Optical Trapping, aad Manipulation of Single Molecules in Solution

摘要

The detection of a single molecule in solution has recently aroused considerable interest, both for its analytical utility and for gaining insight into the chemistry and dynamics at the single-molecule level. The ability to manipulate a single molecule in solution has even more exciting possibilities. In this communication, we present our investigation of the diffusional behavior of a single molecule near the focal volume of a confocal fluorescence microscope. We report the first direct optical trapping and manipulation of a single molecule in solution, in particular, a single 1 DNA molecule (approx = 48 kb, isolated from the bacteriophage lambda and purchased from New England Biolabs) labeled with YOYO dye (approx = 1 YOYO per 20 bases) under conditions in which the K DNA sapercoils, Many studies have been made on DNA in which it is stretched or transported by attaching DNA to a polystyrene bead and using an optical tweezer to exert force on the bead. This report uses the same physical principles, but it describes the direct action of the radiation field on DNA.