Compact tridentate ligands for enhanced aqueous stability of quantum dots and in vivo imaging

We describe here a simple and versatile route for the preparation of a tridentate ligand that not only provides stable interactions with colloidal semiconductor nanocrystals (quantum dots, QDs) but also makes them water soluble. The designed ligand incorporates a biocompatible solubilizing polyethylene glycol (PEG) chain connected to a tridentate thiol motif with improved affinity towards the QDs surface. Stability experiments revealed better resistance to various drastic conditions compared to classical dihydrolipoic-based ligands. The enhanced stability of the assembly also enabled in vivo imaging experiments using near infrared-emitting QDs.