Tuning toxic properties of polyethylene glycol-based deep eutectic solvents for achieving greener solvents

Low toxicity is one of the key properties for the sustainable application of polyethylene glycol-based deep eutectic solvents (PEG-based DESs) in separation, catalysis, biochemistry and analysis. However, the toxicity of PEG-based DESs is not reported and the rules for obtaining lower toxicity is needed to explore. Herein, the cytotoxicity of several PEG-based DESs against lung cancer cell (A549) was evaluated by CCK-8 assay, and strategies for the minimizing and tuning the toxicity of DESs are for the first time proposed from the aspects of mole ratio, hydrogen-bonding donor, hydrogen-bonding acceptor, components numbers, and solvent concentration. The results indicated that the DESs are more toxic than their individual components, and the toxicity order of DESs is generally in accordance with the individual components except for the hydrogen-bonding donor. This work would provide possible routes for the decrease of DESs toxicity for sustainable and green chemistry.