Synthesis and evaluation of novel galactose-carbocyanine fluorescent contrast agents with enhanced hydrophilicity and rigid molecular constraint

A new carbocyanine optical molecular probe with enhanced water solubility and constrained structural conformations was designed and synthesized. The near infrared (NIR) fluorescent probe contains a nonionic D-galactopyranose, which could improve water solubility of the probe and enhance uptake in tumors mediated by glucose transporter. The possibility of multiple attachment points provides the potential to conjugate diverse bioactive molecules to the probe. We developed an efficient synthetic method that is optimized for large-scale synthesis. Preliminary in vivo biodistribution studies show that the probe is rapidly cleared from blood and localize in the liver as early as 5 minutes post-injection of the probe in nude mice. Additional studies to evaluate the tumor uptake of the probe and its bioactive peptide conjugates are in progress.