cyanine dye bioconjugates useful for diagnostic imaging and therapy are disclosed . the conjugates include several cyanine dyes with a variety of bis - and tetrakis homologes . the compounds are be conjugated to bioactive peptides , carbohydrates , hormones , drugs , or other bioactive agents . the small size of the compounds allows more favorable delivery to tumor cells as compared to larger molecular weight imaging agents . the various dyes are useful over the range of 350 to 1 , 300 nm , the exact range being dependent upon the particular dye . the use of a biocompatible organic solvent such as dimethylsulfoxide helps to maintain the fluorescence of the compounds . the inventive compounds are useful for diagnostic imaging and therapy , in endoscopic applications for the detection of tumors and other abnormalities , for localized therapy , for photoacoustic tumor imaging , detection and therapy , and for sonofluorescence tumor imaging , detection and therapy .