Ecotoxicity and Hemolytic Activity of Fluorinated Ionic Liquids

Abstract

The task-specific design of ionic liquids (ILs) has emerged in several industrial and pharmaceutical applications. The family of ILs with fluorine tags equal to or longer than four carbon atoms, the fluorinated ionic liquids (FILs), combine the best properties of ILs with the ones of perfluorinated compounds, and are being designed for several specific purposes. In the pharmaceutical field, there is an urgency to search for novel antibacterial agents to overcome problems associated to antimicrobial resistances. Then, the main purpose of this work is to evaluate the environmental impact and the ability of FILs to be used as antibacterial agents against Pseudomonas stutzeri bacteria. Beyond its rare pathogenicity, these bacteria are also used as a bioremediation agent to treat several contamination sites. Then, it is important to determine which FILs have antibacterial properties, and which do not impact the bacterial growth. The biocompatibility of FILs was also evaluated through their hemolytic activity and represent a step forward the application of FILs in pharmaceutical applications. The results proved that high concentrations of FILs can have a reduced ecotoxicity and a high biocompatibility. [C8C1Im][CF3SO3] was identified as the most promising compound to be used as an antibacterial agent since it prevents the growth of bacteria at concentrations compatible with the red blood cells’ viability.

Understanding the phase and solvation behavior of fluorinated ionic liquids

“…However, the elongation of the hydrogenated or fluorinated side chains leads to a higher charge delocalization and lipophilicity, resulting in a higher permeation of cellular membranes, and consequently higher cytotoxicity [19,57]. Furthermore, hemolytic tests reveal that red blood cell lysis only occurs at high FIL concentrations [59]. Herein, the lowest hemolytic rates were achieved with both imidazolium and pyridinium cations conjugated with the perfluoropentanoate anion [59].…”

“…Regarding the environmental impact of FILs, cytotoxicity is a critical parameter to evaluate their use for a variety of applications. According to the works published in the literature, this parameter is highly dependent on a variety of factors, such as the organism where tests are performed and the exposure time [19,[57][58][59][60]. The cytotoxicity of several FILs has been evaluated in different human cell lines (human colon carcinoma cells (Caco-2), human hepatocellular carcinoma cells (HepG2), human umbilical vein cell line (EA.hy926), and spontaneously immortalized human keratinocyte cell line (HaCaT)) [19,57,58].…”

“…Furthermore, hemolytic tests reveal that red blood cell lysis only occurs at high FIL concentrations [59]. Herein, the lowest hemolytic rates were achieved with both imidazolium and pyridinium cations conjugated with the perfluoropentanoate anion [59]. Although the limited FILs solubility in the tested medium hampers a proper analysis about the effect of the hydrogenated and fluorinated side chain elongation, it was clear by the profiles achieved that the hemolysis accomplished higher levels in long chain-based FILs at similar or reduced concentrations than short chain-based ones [59].…”

Understanding the Absorption of Fluorinated Gases in Fluorinated Ionic Liquids for Recovering Purposes Using Soft-SAFT

“…22,25−34 For instance, FILs based on perfluoroalkyl chains composed of four carbons can have total miscibility in water, 32−34 superior aggregation behavior by the formation of different stable self-assembled structures in aqueous solutions, 31−34 and negligible cytotoxicity 35−37 and ecotoxicity. 38,39 Therefore, it is possible to design ad-hoc FILs with improved ability to absorb F-gases, and with intrinsic properties that comply with the principles of green chemistry and sustainability.…”

“…Recently, fluorinated ionic liquids (FILs), defined in this work as ILs with anionic and/or cationic perfluoroalkyl chains with a minimum of four carbons, have received great attention in the solvation of fluorine compounds. − They are considered three-in-one solvents due to the formation of three nanosegregated domains (polar, hydrogenous, and fluorous). − This enhanced solubilization power, combined with the increased free volume due to the asymmetry between the counterions, size of the fluorinated chains, and its rigidity resulting from the strong carbon–fluorine bonds, − ,, makes FILs appealing compounds for F-gases applications. Their improved properties are found by gathering the best of the conventional ILs (insignificant vapor pressure, superior thermal stability, diminished flammability, and easy recovery and recycling) with the characteristic chemical and biological inertness, low surface tension, and superior surfactant behavior of the perfluoroalkyl compounds. ,− For instance, FILs based on perfluoroalkyl chains composed of four carbons can have total miscibility in water, − superior aggregation behavior by the formation of different stable self-assembled structures in aqueous solutions, − and negligible cytotoxicity − and ecotoxicity. , Therefore, it is possible to design ad-hoc FILs with improved ability to absorb F-gases, and with intrinsic properties that comply with the principles of green chemistry and sustainability.…”