Cellular uptake, cytotoxicity, and ROS generation with silica/conducting polymer core/shell nanospheres

The cellular response to conducting polymer (CP) nanospheres with similar physical properties was evaluated by in vitro cellular uptake and cytotoxicity in mouse macrophage RAW 264.7 and rat pheochromocytoma PC-12 cells. Four different CPs (polythiophene, poly(3,4-ethylenedioxythiophene), polyaniline, and polypyrrole) were deposited onto silica nanoparticles with a diameter of Ca. 22 nm. Cellular uptake of silica/CP core/shell nanospheres in both cell lines was observed by transmission electron microscopy and they were internalized via phagocytosis and endocytosis. Cytotoxic effects were systemically assessed using live-cell microscopy, viability, oxidative stress, and lactate dehydrogenase assays. Silica/polythiophene core/shell nanospheres were the most toxic in both cell lines examined, because of the cellular effects of sulfur atoms. On the other hand, silica/polypyrrole core/shell nanospheres caused the lowest levels of toxicity in both cell lines. Furthermore, both rat and mouse cell viability was concentration-dependent with the nanospheres. These findings enhance nanotoxicological information regarding CP nanospheres when used with macrophage and neuronal cells, which may be useful in their application in bioelectronic and biomedical fields. (C) 2011 Elsevier Ltd. All rights reserved.