| The field of single molecule tracking based on gold and dye-labeled tracer molecules has been instrumental in changing the view about the structure-dynamics-function relationships in cellular membranes. However, these traditional probes are limited concerning their size and photostability, respectively. This work presents the successful development of a sonochemical synthesis method for high-quality CdSe/ZnS quantum dots, and their subsequent characterization. Also reported is the design of a new quantum dot-based probe for single molecule imaging on phospholipid membranes. Nanocrystal coatings were especially designed for direct conjugation of these small, photostable, water soluble CdSe/ZnS quantum dots to membrane-bound phospholipids in model membranes and on cell surfaces. Using wide-field single molecule fluorescence microscopy, the trajectories of the quantum dot-labeled lipids were studied, and 1:1 quantum dot:phospholipid labeling was verified. The small size (<10nm) and high photostability of these custom-built, state of the art imaging probes is particularly interesting for fluorescence-based molecular imaging where high sensitivity is required. Results from tracking experiments on dye and quantum dot-conjugated lipids in model and cell membranes are provided, which verify the biocompatibility and bioconjugation of the quantum dot probes developed in this work. |
