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Figure 6.5 Movement of a QD - EGF - EGFR on
an A431 cell taken with the programmable array
microscope (PAM). Frames 1 (green, 0 s), 80
(red, 13.3 s), and 160 (blue, 26.6 s) of a 300-
frame film (50 s total) shown as a three-color
overlay. Diffusion and blinking of single
QD - EGF - EGFR are visualized. Arrow 1 indicates
aQD - EGF - EGFR that did not move; arrow 2, a
QD - EGF - EGFR that has blinked off in frame
160; and arrow 3 a mobile QD - EGF - EGFR. Data
were recorded with an exposure time of 33ms at
a rate of
6Hz.
6.6
Concluding Remarks
The field of cellular imaging has bene ted enormously from parallel technological
developments leading to dramatic increases in sensitivity, spatial and temporal
resolution, and selectivity. Luminescent quantum dots, as well as silica-based
nanoparticles and nanodot clusters of noble metals not featured in this chapter
(see [23]), provide single-molecule sensitivity in imaging systems designed for
studies of living cells. We favor wide-
eld microscope systems for this application
because of their much higher acquisition speed, particularly in combination with
electron multiplying CCD cameras that afford the ultimate performance at detected
light levels of
100 photons/pixel. The programmable array microscope featured
here offers optical sectioning in combination with resolution in time ( uorescence
lifetimes), anisotropy (FRET, diffusion), space (hyperspectral imaging, diffusion),
and chemistry (photoreactions) [24].
Note added in proof: This article was completed in November 2006.
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Acknowledgments
The authors acknowledge support for the project from EU FP5 project QLG1-
CT-2000-01260 and for development of the PAM through EU FP6 Project 037465
 
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