Homing peptide conjugated quantum dots for colorectal cancer imaging

Abstract

Peptide-labeled quantum dots (QDs) have found wide applications in tumor imaging. Especially, homing peptide labeled QDs can target specific tumor tissues and thus serve as an indicator of the location of the tumor. However, most tumor homing agents target general markers instead of a biomarker specific to a certain type of cancers; for example, no specific imaging agents have been reported for colorectal cancer yet. Herein, we report the conjugation of a colorectal tumor homing peptide TCP-1-H6 with QDs by metal affinity-driven assembly, and also the characterization of the details of the assembly process by capillary electrophoresis. TCP-1-H6 conjugated QDs (TCP-1-H6-QD) were then applied to the imaging of colorectal cancer cells as well as tumor tissues from a mouse model of orthotopic colorectal cancers. TCP-1-H6-QD efficiently targeted colon 26 cells, and were internalized into the intracellular space. On tumor tissue sections, TCP-1-H6-QD specifically labeled the tumor tissues but not health tissues. These results indicate that TCP-1-H6-QD retains the unique homing property of the peptide and thus can be used for specific imaging of colorectal cancer. This method thereby widens the road for specific identification and diagnosis of cancer.