MICROSCOPY Vol.43▶No.3 2008

Functional Investigation Using Quantum Dot Multiple Staining

Johbu Itoh

Abstract: Quantum dots (Qds) are nanocrystal semiconductor fluorophores consisting of a cadmium selenide core and zinc sulfide or cadmium sulfide shell.  They have many advantages over conventional fluorophores including prolonged signal due to photostability, and reinforcement of weak positive reactions. In addition, the confocal laser scanning microscopic (CLSM) dye spectrum analysis system (META, Carl Zeiss, Germany) is utilized.  This system ensures optimum specimen illumination and efficient collection of reflected or emitted light and uses an innovative way of separating fluorescent emissions.
In this report, we have demonstrated that multiple Qds signals simultaneous detection from proteins and its transformed factors by CLSM-META. In addition, weak signals produced by conventional immunofluorescence and/or enzyme-labeled antibody methods have been significantly enhanced using Qd labeling, and comparable signals from Qds in the same specimen area have been detected in both transmittance and META modes.
In summary, we believe that Qds represent a breakthrough for the fluorescent antibody method, expanding its already very wide application, and have demonstrated the potential of Qds for the observation of fluorescence microscopy, CLSM, and immunoelectronmicroscopy.
Our results suggest that multiple very weak immunoreactions seen by traditional immunohistochemical techniques can be greatly intensified, a useful feature for widely field.

Key words: Immunohistochemistry, quantum dots, confocal laser scanning microscopy, spectrum analysis, multiple detection