Cyanine and indocyanine dye compounds and bioconjugates are disclosed. The present invention includes several cyanine and indocyanine dyes, including bioconjugates of the same, with a variety of bis- and tetrakis (carboxylic acid) homologues. The compounds of the invention may be conjugated to bioactive peptides, carbohydrates, hormones, drugs, or other bioactive agents. The small size of compounds of the invention allows favorable delivery to tumor cells as compared to larger molecular weight imaging agents. Further, use of a biocompatible organic solvent such as dimethylsulfoxide may be said to assist in maintaining the fluorescence of compounds of the invention. The compounds and bioconjugates herein disclosed are useful in a variety of medical applications including, but not limited to, diagnostic imaging and therapy, endoscopic applications for the detection of tumors and other abnormalities, localized therapy, photoacoustic tumor imaging, detection and therapy, and sonofluorescence tumor imaging, detection and therapy.