Synthesis and characterization of a glycine- modified heptamethine indocyanine dye for in vivo cancer-targeted near-infrared imaging

Abstract

Tao Liu,1 Shenglin Luo,1 Yang Wang,1 Xu Tan,1 Qingrong Qi,2 Chunmeng Shi1 1Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, People's Republic of China; 2Key Laboratory of Drug-Targeting and Drug-Delivery Systems of the Ministry of Education, Department of Medicinal Chemistry, West China School of Pharmacy, Sichuan University, Chengdu, People's Republic of China Abstract: Near-infrared (NIR) fluorescent sensors have emerged as promising molecular tools for cancer imaging and detection in living systems. However, cancer NIR fluorescent sensors are very challenging to develop because they are required to exhibit good specificity and low toxicity as an eligible contrast agent. Here, we describe the synthesis of a new heptamethine indocyanine dye (NIR-27) modified with a glycine at the end of each N-alkyl side chain, and its biological characterization for in vivo cancer-targeted NIR imaging. In addition to its high specificity, NIR-27 also shows lower cytotoxicity than indocyanine green, a nonspecific NIR probe widely used in clinic. These characteristics suggest that NIR-27 is a promising prospect as a new NIR fluorescent sensor for sensitive cancer detection. Keywords: near-infrared (NIR), heptamethine dye, cancer-targeted imaging