Preclinical evaluation of a novel cyanine dye for tumor imaging with in vivo photoacoustic imaging

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, cost-effectiveness, 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 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 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. Bu. These results indicate that IC7-1-Bu is a promising PAI contrast agent for cancer imaging without conjugation of targeting moieties.