Synthesis of a cationic poly(p-phenylenevinylene) derivative for lysosome-specific and long-term imaging

The development of long-term imaging agents and subcellular imaging materials is of great importance in the research of cancer cell behaviors. In this work, a cationic poly(p-phenylenevinylene) derivative (PPV) is designed and synthesized to link quaternized N-methyl-imidazole groups as pendants which endow the polymer to bear positive charges. Absorption and fluorescence emission spectra of PPV display a large Stokes shift of 102 nm which is much larger than the commercial cell dyes. Positively charged polymer could adsorb onto the surface of cells via electrostatic interactions followed by cell endocytosis process to enter cells. Importantly, PPV barely has influence on the cell viability through cytotoxicity analysis. The colocalization data demonstrates that PPV and commercial lysosome-specific dye are highly colocalized in the same region, indicating that the green fluorescent PPV mainly distributes in the lysosomes. Moreover, the continuous imaging investigation shows that PPV could stay in cells for more than seven days while the commercial Lyso-Tracker would be extruded by cells after three days. PPV exhibits superior capabilities including strong fluorescence, large Stokes shift, good biocompatibility and high photostablity, which has great potential in the applications of cellular process monitoring.