Forming highly fluorescent near-infrared emitting PbS quantum dots in water using glutathione as surface-modifying molecule

► We developed a new facile method for transferring oil-soluble PbS QDs into water with glutathione. ► The resulting water-soluble GSH-capped PbS QDs show strong NIR fluorescence (PL QY >30%). ► We revealed the influence of ligand exchange with five different types of thiol molecules. ► We explored the conditions of QD water solubilization, the stability, and cytotoxicity. ► The resultant water-soluble NIR-emitting PbS QDs are promising for the imaging of living animals.