The present invention provides methods for determining the presence of immobilized 
nucleic acid employing unsymmetrical 
cyanine dyes that are derivatives of 
thiazole orange, a 
staining solution and select fluorogenic compounds that are characterized as being essentially non-genotoxic. The methods comprise immobilizing 
nucleic acid, single or 
double stranded DNA, 
RNA or a combination thereof, on a 
solid or 
semi solid support, contacting the immobilized 
nucleic acid with an unsymmetrical 
cyanine dye compound and then illuminating the immobilized nucleic acid with an appropriate 
wavelength whereby the presence of the nucleic acid is determined. The 
cyanine dye compounds are typically present in an aqueous 
staining solution comprising the dye compound and a 
tris acetate or 
tris borate buffer wherein the solution facilitates the contact of the dye compound and the immobilized nucleic acid. Typically the 
solid or semi-
solid support is selected from the group consisting of a polymeric gel, a membrane, an array, a glass bead, a 
glass slide, and a polymeric 
microparticle. Preferably, the polymeric gel is 
agarose or 
polyacrylamide. The methods employing the non-genotoxic compounds represent an improvement over commonly used methods employing 
ethidium bromide wherein the present methods retain the advantages of 
ethidium bromide, ease of use and low cost, but without the disadvantageous, known 
mutagen requiring special handling and waste procedures.