High affinity scFv-hapten pair as a tool for quantum dot labeling and tracking of single proteins in live cells

We describe a general approach to label cell surface proteins using quantum dots (QD) for single-molecule tracking. QDs coated with small-hapten modified peptides are targeted to cell surface fusion proteins containing the corresponding single-chain fragment antibody (scFv). The approach is illustrated with the small hapten fluorescein (FL) and a high-affinity anti-FL scFv fused to two different proteins in yeast and murine neuronal cell line N2a.