Preparation and Characterization of Deep Eutectic Solvents for Water-Insoluble Drugs’ Solubilization

Abstract Deep eutectic solvents have emerged as tunable and sustainable alternatives to conventional organic solvents for pharmaceutical applications. In this work, 11 choline chloride-based DESs were prepared using sorbitol, malonic acid, xylitol, thiourea, and mixed hydrogen bond donor systems at different molar ratios. The density and pH of all the prepared DESs were measured at different temperatures T = (298.15 to 343.15) K and pressure p = 101.305 kPa. Subsequently, the refractive indices of all the prepared DESs were measured at temperature T = 298.15 K and pressure p = 101.305 kPa. Further, polarized optical microscopy (POM) and contact angle were used to evaluate the microstructural behavior and crystallinity of deep eutectic solvents and the wettability and surface interaction of deep eutectic solvents, respectively. Hydrogen-bond formation upon mixing was investigated using FTIR spectroscopy, and TGA and DSC thermograms were used to understand the thermal stability and thermal behavior of all the studied DESs. Finally, the sigma profile and the sigma potential of all of the studied molecules were generated and analyzed using quantum chemical calculations.