Stable and Reversible Functionalization of the Native Phosphate Groups on Live Cells

Surface modification of live cells has important biomedical and therapeutic applications. Current methods to label cells require artificial cell surface engineering (via metabolic, docking or anchoring methods) before conjugative chemistries, which is not always trivial to accomplish and/or not appropriate for multiple cell types. A new method without the need of initial cell surface anchoring will greatly facilitate live cell surface labelling. Herein, we provide a general strategy for live cell functionalization that utilizes the native phosphate groups on every cell. We have designed a dual conjugation cargo molecule with a cationic side chain for non-covalent bonds with the negatively-charged cell surface and a phosphoric acid containing ligand for covalent bonding with the cell membrane phospholipid phosphate. Our dual conjugation strategy on live cell surfaces is non-toxic with enhanced stability to functionalize live cells. This provides a stable, reversible and reusable reagent with direct conjugation strategy to image live cell membranes.\n\nSignificanceThe ability to label live cell surfaces has many applications ranging from in vivo monitoring of cell populations to diagnostics and use of cells as drugs. Thus far, most reported strategies to label cell surfaces are not broadly applicable or easy to use for any cell type as it has relied on engineering cells with artificial moieties or conjugations that may affect cellular function. We provide a general solution to this long-standing problem by developing two-sided functionalization of the phosphate moieties that are ubiquitous on all cells. We show one application of our chemical strategy as a general-purpose live-cell membrane imaging reagent with long-time stability. Our strategy is broadly applicable to imaging, sensing, drug delivery, bioengineering, diagnostics and cell therapy.\n\nO_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY