Evaluation of quantum dot cytotoxicity based on intracellular uptake

The cytotoxicity of different surface-coated CdSe/CdS (core shell) Quantum Dots (QD) based on extracellular and intracellular nanoparticle exposure levels in cells were characterized to prove that the number of nanoparticles taken up into cells play an important role in determining cell toxicity. The QD surface coatings used were nonPEG-substituted (bare), or 750 and 6000 weight average molecular weight. Cytotoxicity with higher concentration for all surface modified QDs were also observed, with nonPEG-substitted QDs displaying the highest cell toxicity. The QDs were exposed to acidic and highly oxidative environments to simulate the biological degradation within lysomes and peroxisomes. The results showed that the exposure concentrations that led to equivalent QD uptake in cells for different surface-modified QDs results in no statistical difference in cytotoxicity for bare.