Observing photophysical properties of quantum dots in air at the single molecule level: Advantages in microarray applications

Quantum dots (QDs) are promising fluorescent tags for microarrays. Because most microarrays are analyzed under dry conditions, it is necessary to examine the photo properties of QDs in air. We demonstrate that the photophysical characteristics of individual quantum dots are different at the liquid/solid interface compared with QDs at the air/solid interface by observing them through a wide-field fluorescence microscope. QDs in air show higher photo-stability, higher fluorescence signal, slower spectral blue shift rate, less blinking and shorter bulk fluorescence lifetime than those in solution. These beneficial properties indicate QDs are good alternative fluorescent probes for microarrays.