Abstract: The disclosure is of fluorescent deoxyribonucleic acid intercalating agent derivatives of activated polysaccharides such as cyanogen halide-activated agarose and the like. The derivatives are useful fluorescent stain ingredients of water-insoluble gels used to fractionate deoxyribonucleic acids and deoxyribonucleic acid fragments by gel electrophoresis techniques. As ingredients of electrophoretic grade gels, the derivatives of the invention function as fluorescent stains to provide direct visualization of the deoxyribonucleic acids and their fractions, under the excitation of shortwave, ultraviolet radiation.