Quantitative two-color fluorescence cross-correlation spectroscopy in the analysis of polymerase chain reaction.

We present results of an approach in which low-density labeled DNA itself provides an amplification of the cross-correlated fluorescent signal in the two-color cross-correlation function. Tetramethylrhodamine-4-dUTP and Cy5-dCTP are incorporated by polymerase chain reaction at multiple positions of the same 217 bp target DNA. We call this novel approach the 'two-color FCS signal amplification'. The signal amplification is an example for interactions of two ligands with different colors at multiple positions of the same target.