Figure 2. Phospholipid Conjugates Hydrophobically Insert into Cell Membranes.

Cells were modified with increasing concentrations of either DSPE-PEG₂₀₀₀-biotin or DSPE-PEG₂₀₀₀-DBCO through one of two methods: (1) resuspension in phospholipid-containing buffer (ex vitro), or (2) active culture in phospholipid-containing media (in vitro). Cells were subsequently analyzed by flow cytometry using streptavidin- or azide-conjugated Alexa Fluor 488 to assess the presence of biotin and DBCO moieties, respectively, on the cell surface. Both adherent MCF-7 cells and suspensive Raji cells can be successfully modified with DSPE-PEG₂₀₀₀-biotin or DSPE-PEG₂₀₀₀-DBCO through both the ex vitro and in vitro approaches. While insertion experiments were performed in triplicate, a representative trial of each condition is shown here. A quantitative analysis of the triplicate data is presented in Figure S2 of the Supporting Information.