Purpose(s)
Malignant tumors exhibit an elevated rate of glycolysis in comparison with normal cells. The increased demand for glucose from tumor cells induces an increased expression of glucose transporters (GLUTs) on the cell surface, which can be used as a strategy to explore promising non-invasive imaging contrast agents. In this study, we designed and synthesized a pH-responsive NIR fluorescence chemosensor which can simultaneously detect mitochondria and lysosomes at the cellular level and further enable tumor-targeted imaging in a tumor-bearing mice model. To improve its tumor targeting ability and solubility, a glucosamine functional group was introduced to obtain the probe CyT.
Method(s)
The synthetic route for CyT based on heptamethine dyes is shown in Fig. 1. The chemical structures of the compounds were characterized by 1H NMR, 13C NMR, and ESI-MS analysis. Absorption and fluorescence spectra of CyT at different pHs were measured.
Result(s)
A glucosamine modified near-infrared cyanine dye CyT sensitive to pH was synthesized. Due to the different pH of mitochondria and autolysosomes, the probe can simultaneously investigate mitochondria and autolysosomes in live cells. Moreover, this fluorescent probe can be applied to tumor targeting imaging, due to the introduction of glucosamine groups.
Conclusion(s)
In summary, a novel pH-activated NIR fluorescence chemosensor based on glucosamine modified cyanine has been designed and synthesized. CyT selectively accumulates in mitochondria and exhibits strong fluorescence at 568 nm excitation. During mitophagy, when damaged mitochondria lysed by lysosomes evolved into autolysosomes, CyT was transformed into CyTH with an ample shift and exhibited strong fluorescence at 647nm excitation. Therefore, CyT can be used to detect mitochondria and autophagy lysosomes simultaneously in tumor cells. Moreover, this fluorescent probe was also successfully applied to tumor targeted imaging, due to the introduction of glucosamine groups.