3-Dimensional Tracking of Non-blinking 'Giant' Quantum Dots in Live Cells

• Published in: Advanced functional materials Vol. 24; no. 30; pp. 4796 - 4803
• Main Authors: Keller, Aaron M., Ghosh, Yagnaseni, DeVore, Matthew S., Phipps, Mary E., Stewart, Michael H., Wilson, Bridget S., Lidke, Diane S., Hollingsworth, Jennifer A., Werner, James H.
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 13.08.2014
• Subjects: Dynamics; Fluorescence; fluorescence imaging; live cell imaging; non-blinking; Quantum dots; Receptors; Semiconductors; single particle tracking; stable molecular probe; Three dimensional; Time; Tracking
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201400349

While semiconductor quantum dots (QDs) have been used successfully in numerous single particle tracking (SPT) studies due to their high photoluminescence efficiency, photostability, and broad palette of emission colors, conventional QDs exhibit fluorescence intermittency or ‘blinking,’ which causes ambiguity in particle trajectory analysis and limits tracking duration. Here, non‐blinking ‘giant’ quantum dots (gQDs) are exploited to study IgE‐FcεRI receptor dynamics in live cells using a confocal‐based 3D SPT microscope. There is a 7‐fold increase in the probability of observing IgE‐FcεRI for longer than 1 min using the gQDs compared to commercially available QDs. A time‐gated photon‐pair correlation analysis is implemented to verify that selected SPT trajectories are definitively from individual gQDs and not aggregates. The increase in tracking duration for the gQDs allows the observation of multiple changes in diffusion rates of individual IgE‐FcεRI receptors occurring on long (>1 min) time scales, which are quantified using a time‐dependent diffusion coefficient and hidden Markov modeling. Non‐blinking gQDs should become an important tool in future live cell 2D and 3D SPT studies, especially in cases where changes in cellular dynamics are occurring on the time scale of several minutes. The bioconjugation of non‐blinking ‘giant’ quantum dots to the IgE allergen receptor allows for extended 3D tracking of receptor dynamics in live cells. The extended tracking duration afforded by the stable quantum dot fluorescence emission allows the observation of heterogeneous diffusion occurring on long time scales for individual allergen receptors.