Cytotoxicity of Ionic Liquids on Normal Human Dermal Fibroblasts in the Context of Their Present and Future Applications

The skin is the part of the body that is the most exposed to toxic substances; therefore, the impact of chemicals on the skin should be thoroughly studied prior to their implementation in any industrial-scale application. Herein, we examined and analyzed the influence of the structure of both the cation and anion of 31 different ionic liquids (ILs) on their cytotoxicity against normal human dermal fibroblasts in the context of their present and future potential applications. We found that imidazolium-based ILs combined with dialkyl phosphate anions or with the ethyl sulfate anion are the least cytotoxic. Notably, 1,3-diethylimidazolium ethyl sulfate can be potentially used as a hydraulic fluid similar to the commercially available hydraulic medium based on 1-ethyl-3-methylimidazolium ethyl sulfate. Moreover, the dialkyl phosphate-based ILs are considered as an efficient solvent for the utilization of lignocellulose-based biomass and as an extractant in eco-friendly and cost-effective processes for the extraction of bioplastic. Pyrrolidinium-based and cyano-based ILs, often used as heat transfer media and base fluids for ionanofluids, were also identified herein as good candidates based on their relatively low toxicity compared to other ILs.