Synthesis of Quantum Dot Molecular Beacon Probes

Quantum dots (QDs) are fluorescent semiconductor nanoparticles that have unique optical properties such as a large Stokes shift and a high resistance to photobleaching that make them optimal for biomolecular detection. However, in order to utilize them in a biological environment, the semiconductor QDs must first be made water-soluble. Commercially available QDs are made from cadmium selenide which makes them difficult to use in vivo because of the toxicity of cadmium.  This study utilized non-toxic ZnSe QDs doped with Mn which give them an emission wavelength around 600nm. To make the QDs water soluble we utilized 2 amphipathic lipids (mPEG2000PE and DSPE-PEG(2000) carboxylic acid) and bound them to the surface of the QDs to form a micelle. Any excess lipids were then filtered out to obtain a solution of hydrophilic QDs. Using this method, ZnSe·Mn can then be utilized in a biological setting for applications such as conjugating to proteins and molecular beacons.