Quantum dots possess the unique property of size-tunable emission upon UV excitation. W. Chan/S. Nie

Cytotoxicity of Nanoparticles

The unique material properties of nanomaterials have been exploited in several, proposed biomedical applications; however, questions about the potential cytotoxicity of nanomaterials have raised concerns about their future utility in vivo.

Using primary hepatocyte in an in vitro liver tissue model, we tested the cytotoxicity of CdSe-core QDs and found they were acutely toxic under certain, extreme conditions. We found that cytotoxicity correlated with the liberation of free Cd 2+ ions due to deterioration of the CdSe lattice and could be modulated by processing parameters, exposure to UV, and surface coatings. When appropriately coated, CdSe-core QDs were rendered nontoxic and could be used to track cell migration and reorganization in micropatterned cultures vitro over many days. The work provides criteria for the use of QDs in vitro and especially in vivo, where deterioration over time may occur. Pictures below show phase contrast micrograph (left) and fluorescence image (right) of micropatterned hepatocytes labeled with CdSe QDs and surrounded by fibroblasts to stabilize hepatocyte function. Derfus et al (2004). Nanoletters .

We are also investigating issues affecting nanomaterial toxicity in vivo such as opsonization, uptake by the reticuloendothelial system, and clearance. Together these studies will guide the design and implementation of nanotechnology-based strategies to improve human health.

Phase contrast micrograph of micropatterned array of hepatocyte colonies (~100 um) surrounded by fibroblasts on day 1 of co-culture and corresponding fluorescence image (B) of QD labeled
hepatocytes. Scale bar corresponds to 100 um.

Derfus et al (2004). Nanoletters .