DNA measurements by using fluorescence correlation spectroscopy and two-color fluorescence cross correlation spectroscopy.

FCS and FCCS measurements provide two important analytical parameters, the average number of molecules in the detection area and the translational diffusion constant of the molecules at the single molecule level. Considering these properties, FCS and FCCS have been applied to analysis of the cellular environment and dynamic processes of molecules in the living cell. More recently, a systematic approach for the analysis of macromolecule complex formation has focused on the new field of single molecule detection in the post-genome era. In this work, we tested the sensitivities of FCS and FCCS based on the distance between fluorophores in DNA as a model macromolecule complex. The results show that FCCS is not limited by the size of the macromolecular complex even in a very small detection area.