Photoacoustic imaging (PA imaging or PAI) has shown great promise in the detection and monitoring of
cancer. Although nanocarrier-based
contrast agents have been studied for use in PAI, small molecule
contrast agents are required due to their ease of preparation, costeffectiveness, and low toxicity. Here, we evaluated the usefulness of a novel cyanine
dye IC7-1-Bu as a PAI
contrast agent without conjugated targeting moieties for in vivo
tumor imaging in a mice model. Basic PA characteristics of IC7-1-Bu were compared with
indocyanine green (ICG), a Food and Drug Administration approved
dye, in an aqueous
solution. We evaluated the
tumor accumulation profile of IC7-1-Bu and ICG by in vivo fluorescence imaging. In vivo PAI was then performed with a photoacoustic tomography system 24 and 48 h after
intravenous injection of IC7-1-Bu into
tumor bearing mice. IC7-1-Bu showed about a 2.3-fold higher PA signal in aqueous
solution compared with that of ICG. Unlike ICG, IC7-1-Bu showed high
tumor fluorescence after
intravenous injection. In vivo PAI provided a
tumor to background PA signal ratio of approximately 2.5 after
intravenous injection of IC7-1-Bu. These results indicate that IC7-1-Bu is a promising PAI
contrast agent for
cancer imaging without conjugation of targeting moieties.