Functionalized carbon nanotubes have already demonstrated great biocompatibility and potential for drug delivery. We have synthesized acid oxidized and non-covalently PEGlyated single-walled carbon nanotubes (SWNTs), which were previously prepared for drug delivery purposes, and explored their potential for detoxification in the bloodstream. Our investigations of the binding of SWNTs to a pore-forming toxin pyolysin show that SWNTs prevented toxin-induced pore formation in the cell membrane of human red blood cells. Quantitative hemolysis assay and scanning electron microscopy were used to evaluate the inhibition of hemolytic activity of pyolysin. According to Raman spectroscopy data, human red blood cells, unlike HeLa cells, did not internalize oxidized SWNTs. Molecular modeling and circular dichroism measurements were used to predict the 3-D structure of pyolysin (domain 4) and its interaction with SWNTs. The tryptophan-rich hydrophobic motif in the membrane-binding domain of pyolysin, a common construct in a large family of cholesterol-dependent cytolysins, shows high affinity for SWNTs.