We describe a quantum dot (qdot) phase transfer protocol using ligand exchange and the amino acid histidine. The histidine molecule was chosen in order to first displace the organic encapsulation and second to provide a weakly chemisorbing intermediate at the qdot ionic interface. Because the histidine-capping is easily displaced by an assortment of different molecules while in aqueous buffers, we refer to this approach as modular.  Characterization via FTIR and NMR revealed the extent of ligand exchange, and provide insights into the interfacial binding mechanism.  The colloidal and photo stability of the qdots was probed via UV-vis and steady state fluorescence. The modularity of this approach is shown by tailoring the qdot surface charge via sequential ligand exchange using mixed-monolayers of carboxylic acid and polyethylene glycol terminated thiols. The ability of the histidine-capped qdots to bind proteins and other biomaterials will also be discussed.

Phase transfer and biofunctionalization of Qdots via the histidine mediated phase transfer method

244th National Meeting (2012)

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