Mannosylated semiconductor quantum dots for the labeling of macrophages

Quantum dots show strong fluorescence emission and long stability compared with classical organic fluorescent dyes; therefore, quantum dots take the place of other dyes in Western blot, immunostaining and bioimaging. Since macrophage plays crucial roles in many pathophysiological processes, tracking macrophage migration, homing and fate is important for understanding the complex roles of macrophages in disease or developing disease diagnosis. Because of the high expression of mannose receptor on macrophage, mannosylation is an attractive strategy to label macrophage. In this study, using polyethylene-glycol (PEG) (M.W. 2,000; PEG2,000)-coated quantum dots, we prepared mannosylated PEG2,000 (Man-PEG2,000) quantum dots for labeling macrophage. The uptake characteristics of Man-PEG2,000 quantum dots were investigated by primary cultured peritoneal macrophages. The uptake of Man-PEG2,000 quantum dots was inhibited by an excess amount of mannose, suggesting mannose receptor-mediated uptake of Man-PEG2,000 quantum dots. The result of MTT assay suggested the extremely low cytotoxicity of Man-PEG2,000 quantum dots. In conclusion, the Man-PEG2,000 synthesized is safe and is taken up by macrophage mannose receptor recognition.