We describe the synthesis of a series of compact ligands made of multi-coordinating (lipoic acid based) anchors, polyethylene glycol or zwitterion groups, and tunable terminal functions.  We combine these ligands with a novel photo-ligation strategy to promote the transfer of QDs to polar and buffer media using such ligands, where in-situ reduction of the dithiolane, achieved under UV irradiation, is coupled with rapid ligand exchange on hydrophobic QDs. This strategy drastically improves previous transfer methods and is well adapted to the in-situ modification of QD surfaces with diverse functionalities. QDs with long term colloidal stability at sub-nanomolar concentrations under a range of biologically relevant conditions have been prepared and tested. This bodes well for in vivo imaging where very small concentrations are used.  We also found that QDs stabilized with zwitterionc ligands are fully compatible with metal-histidine driven self-assembly with control the QD-protein conjugate valence.

Combining ligand design and photo-ligation to transfer hydrophobic quantum dots to hydrophilic media

245th National Meeting (2013)

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