High-Affinity Labeling and Tracking of Individual Histidine-Tagged Proteins in Live Cells Using Ni2+ Tris-nitrilotriacetic Acid Quantum Dot Conjugates

Investigation of many cellular processes using fluorescent quantum dots (QDs) is hindered by the nontrivial requirements for OD surface functionalization and targeting. To address these challenges, we designed, characterized and applied QD-trisNTA, which integrates trisnitrilotriacetic acid, a small and high-affinity recognition unit for the ubiquitous polyhistidine protein tag. Using GD-trisNTA, we demonstrate two-color OD tracking of the type-1 interferon receptor subunits in live cells, potentially enabling direct visualization of protein-protein interactions at the single molecule level.