Fluorescent 6-amino-6-deoxyglycoconjugates for glucose transporter mediated bioimaging

Two novel fluorescent bioprobes, namely, 6N-Gly-Cy3 and 6N-Gly-Cy5, were designed and synthesized for real-time glucose transport imaging as well as potentially useful tracer for galactokinase metabolism. The structure of the bioprobes was fully characterized by ¹H NMR, ¹³C NMR, IR, and HRMS. The fluorescence properties, glucose transporter (GLUT) specificity, and the quenching and safety profiles were studied. The cellular uptake of both bioprobes was competitively diminished by d-glucose, 2-deoxy-d-glucose and GLUT specific inhibitor in a dose-dependent manner in human colon cancer cells (HT29). Comparison study results revealed that the 6N-derived bioprobes are more useful for real-time imaging of cell-based glucose uptake than the structurally similar fluorescent tracer 6-NBDG which was not applicable under physiological conditions. The up to 96 h long-lasting quenching property of 6N-Gly-Cy5 in HT29 suggested the potential applcability of the probe for cell labeling in xenograft transplantation as well as in vivo animal imaging studies.