Determining the cytotoxicity of catanionic surfactant mixtures on HeLa cells

The cytotoxicity of commonly used synthetic surfactants and catanionic mixtures of those was evaluated using MTT on HeLa cells. The 50% inhibition concentration (IC₅₀) for MTT reduction was calculated. The effect on chain length increase and inclusion of polyoxyethylene groups on the toxicity was tested on single surfactant systems. A general trend of increasing toxicity with increasing chain length and the presence of polyoxyethylene groups was observed. The measured IC₅₀ values of catanionic systems lie between those of participating surfactants. The increase in toxicity as the cationic surfactant is added to the anionic one is however not linear. A steep decrease of the IC₅₀ values (and therefore increase in the toxic properties) is observed immediately already at low concentrations of the cationic surfactants. This behavior is analogous to the enzyme activity in catanionic microemulsions.