Quantum dots (QDs) featuring quaternary ammonium functionalities were used to determine the effect of ligand packing density on nanoparticle cytotoxicity.  Thiolate ligand amounts on the QDs were measured using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). The results showed that monodentate molecules were present at higher amounts (~ two fold) on the surface of QDs compared to the bidentate molecules. In the cellular studies, monothiol functionalized QDs were more toxic relative to dithiol functionalized QDs.  Increasing of the surface hydrophobicity also increased the cytotoxicity. QD-induced cytotoxicity was systematically investigated via several determining factors, including the cellular uptake, intracellular liberation of cadmium ions and cellular membrane damage. The results indicated cellular membrane damage could be the primary factor in the mechanism of toxicity of monothiol functionalized cationic QDs due to their higher ligand packing density.

Role of ligand packing density on the cytotoxicity of cationic quantum dots

244th National Meeting (2012)

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