Structure-inherent near-infrared fluorescent probe mediates apoptosis imaging and targeted drug delivery in vivo

Imaging of tumor apoptosis can provide invaluable information in regards to drug treatment effectiveness, drug development and tumor therapeutic response. Thus, the development of apoptotic specific and sensitive targeted fluorescence probes is critically needed. In this work, we developed a novel and simple one-step synthetic method for producing monocarboxylate near-infrared cyanine dyes. The hydrophobic cationic dyes possess advantageous optical properties and good membrane permeability. One hydrophilic zwitterionic probe is able to both increase specificity and image apoptotic cells owing to its inherent chemical structure. Furthermore, we conjugated the probe with the antitumor drug gemcitabine for effective apoptosis imaging and therapeutic targeting of gastric tumors in vitro and in vivo. The novel dye-drug conjugate imaged apoptosis successfully in vitro and in vivo and restricted the growth of SGC7901 subcutaneous xenograft models. This strategy may offer the advantages of NIR apoptosis imaging probes for non-invasive tumor imaging and should provide the application for targeted drug delivery and the evaluation of therapeutic efficacy. (C) 2016 Elsevier Ltd. All rights reserved.