Cytotoxicity profiling of deep eutectic solvents to human skin cells.

The tailor-made character of deep eutectic solvents (DES) turns them very attractive to be used in several applications, including in health-related areas such as pharmaceutical, nutraceutical, and cosmetic industries. However, although DES has been touted as "green" solvents, several works proved that their potential toxicity should not be neglected. Using the premise of DES applicability in the cosmetic and pharmaceutical sectors, we chose two cell lines to work as a skin model (keratinocytes HaCaT and tumor melanocytes MNT-1), to assess DES cytotoxicity. The effect of three different hydrogen bond acceptors (HBA) ([Chol]Cl, [N1111]Cl and [N4444]Cl) and three different hydrogen bond donors (HBD) (hexanoic and butanoic acid, ethylene glycol, 1-propanol and urea) were evaluated through a common viability assay (MTT assay). Results were promising since [Chol]Cl and [N1111]Cl- based DES showed good biocompatibility for the tested cells. [N4444]Cl-based DES, however, showed cytotoxicity for both cell lines, with the HBA being the driver of the toxicity. Interestingly, some compounds increased cell viability in the HaCaT cell line, namely [Chol]Cl, ethylene glycol, hexanoic acid, urea, and all [Chol]Cl and [N1111]Cl-based DES and should be considered as targets for future studies. These results highlight their possible use in cosmetic or pharmaceutical formulations.

Enhanced dissolution of ibuprofen using ionic liquids as catanionic hydrotropes.

The therapeutic effectiveness of a drug largely depends on its bioavailability, and thus ultimately on its aqueous solubility. Hydrotropes are compounds able to enhance the solubility of hydrophobic substances in aqueous media and therefore are extensively used in the formulation of drugs and personal care products. Recently, some ionic liquids were shown to display a strong ability to enhance the solubility of biomolecules through hydrotropy. In this work, the impact of the ionic liquid chemical structures and their concentration on the solubility of ibuprofen was evaluated and compared with the performance of conventional hydrotropes. The results obtained clearly evidence the exceptional capacity of ionic liquids to enhance the solubility of ibuprofen. [C4C1im][SCN] and [C4C1im][N(CN)2] seem to be the most promising ionic liquids for ibuprofen solubilisation, where an increase in the solubility of 60- and 120-fold was observed with ionic liquid concentrations of circa 1 mol kg-1, respectively. Dynamic light scattering and molecular dynamics simulations were used to investigate the mechanism of the IL-mediated drug solubility and the results obtained indicate that the structure of aqueous solutions of ionic liquids and the role it plays in the formation of ionic liquid-drug aggregates is the mechanism driving the hydrotropic dissolution.