Specific Integrin Labeling in Living Cells Using Functionalized Nanocrystals

We present an integrin labeling method using functionalized quantum dots (QDs). Cyclic Arg‐Gly‐Asp (RGD) peptides and a biotin–streptavidin linkage are used to specifically couple individual QDs to integrins of living cells. The spacer distance between the RGD sequence and the QD surface is a crucial parameter to ensure specific binding to individual αvβ3 integrins of osteoblast cells. Despite blinking, the position of single QDs is tracked with nanometer precision and localized diffusive behavior is observed. We show that blinking events do not prevent the acquisition of quantitative parameters from the QD trajectories. Twinkle, twinkle, little dot: Quantum dots (QDs) functionalized by cyclic Arg‐Gly‐Asp (cRGD) peptides using a biotin–streptavidin linkage can specifically label integrins of living cells. The spacer distance between the RGD sequence and the QD surface is a crucial parameter that ensures specific binding to individual αvβ3 integrins of osteoblast cells (see picture). Despite blinking, the position of single QDs is tracked with nanometer precision.