The invention describes the preparation and use of fluorescent stains for nucleic acids derived from unsymmetrical cyanine dyes. In particular, the invention describes unsymmetrical cyanine dyes having a saturated or unsaturated cyclic substituent. The dyes of the invention possess superior fluorescent characteristics when complexed with nucleic acids, and have utility in any application which requires detection of nucleic acids. The presence of the cyclic substituent results in improved permeability in a wide range of living cells, resulting in improved detection of intracellular nucleic acids.
a series of unsymmetrical cyaninedyes plays a critical role in the fluorescence enhancement. Four newly designed unsymmetrical cyaninedyes showed negligible intrinsic fluorescence in the free state and strong fluorescence upon binding to double‐stranded DNA (dsDNA) with a quantum yield of 0.53 to 0.90, which is 2 to 3 times higher than previous unsymmetrical cyaninedyes. A detailed analysis of the