Comparison of near‐infrared fluorescent deoxyglucose probes with different dyes for tumor diagnosis in vivo

Glucose plays a central role in the cellular energy metabolism. Malignant tumors exhibit an elevated rate of glycolysis over normal tissues. In this study, two near‐infrared fluorescent dyes, Cypate and ICG‐Der‐02, with different water solubility, were conjugated to 2‐amino‐2‐deoxy‐d ‐glucose (2DG) to form Cypate‐2DG and ICG‐Der‐02‐2DG, respectively, for NIR fluorescent imaging of tumors in nude mice. The clear routes and tumor targeting abilities of the two NIR fluorescent 2DG probes were compared. Results showed that ICG‐Der‐02‐2DG with higher hydrophilicity was cleared faster by kidneys than the more lipophilic Cypate‐2DG. Cypate‐2DG had slower but stronger tumor targeting ability compared with ICG‐Der‐02‐2DG. To investigate the correlation between the targeting ability of the probe and the glucose transporter (GLUT1) expression levels of cancer cells, the accumulation of Cypate‐2DG in tumors was assessed in MCF‐7/estradiol, U87MG, MCF‐7 and MDA‐MB‐435 tumor xenografts, which express different levels of GLUT1. The results show that both Cypate‐2DG and ICG‐Der‐02‐2DG possess tumor targeting ability on all the tumors examined, with a proportional correlation to GLUT1 expression. The findings demonstrate the broad applicability of these molecular probes for optical imaging of tumors and glucose‐related pathologies. Copyright © 2012 John Wiley & Sons, Ltd.