QD samples were prepared by dispersing a 4 μL drop of QDs suspended in water (525 nm emitting nanocrystals provided by QD Vision) on a microscope slide. A drop of UV-curing adhesive (Norland Products NOA 74) was placed on the dried QDs, a coverslip placed on top, and the sample cured by exposure to a UV source.
HeLa cells on a glass coverslip were fixed at room temperature using 4% paraformaldehyde (Electron Microscopy Sciences 15742-10) for 10 min, permeablized for 2 × 15 min using 0.25% Triton X-100 (Sigma Aldrich 93427) in phosphate-buffered saline, and then treated with an endogenous biotin blocker (Life Technologies E21390). This was followed by treatment with Biotin-XX Phalloidin (Life Technologies B7474) for 20 min, then a 605-nm-emission QD-streptavidin conjugate (Life Technologies Q10151MP) before sealing with a coverslip using Mount Quick medium (Electron Microscopy Sciences 18000).
HeLa cells on a glass coverslip were fixed at room temperature using 4% paraformaldehyde (Electron Microscopy Sciences 15742-10) for 10 min, permeablized for 2 × 15 min using 0.25% Triton X-100 (Sigma Aldrich 93427) in phosphate-buffered saline, and then treated with an endogenous biotin blocker (Life Technologies E21390). This was followed by treatment with Biotin-XX Phalloidin (Life Technologies B7474) for 20 min, then a 605-nm-emission QD-streptavidin conjugate (Life Technologies Q10151MP) before sealing with a coverslip using Mount Quick medium (Electron Microscopy Sciences 18000).