Acrylamide-induced enhanced solubilization of poly(propylene glycol) in aqueous solution

Acrylamide (AM)-induced enhanced solubilization of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) has been phenomenologically reported in a previous study. However, little is known about its mechanism. In this study, poly(propylene glycol) (PPG) serves as a model system to clarify this enhanced solubilization phenomenon, driven by two specific reasons. First, it helps eliminate any interference from PEO segments. Second, the liquid state of low molecular weight PPG proves advantageous for characterizing molecular interactions. The phenomenon of AM-induced enhanced solubilization has been conclusively demonstrated in the PPG system for the first time. Addition of AM consistently raises the cloud point of PPG aqueous solution. Subsequently, the structure and molecular interactions within the PPG/AM aqueous solution were investigated. Notably, there is no robust association or hydrogen bond between PPG and AM molecules; instead, only van der Waals forces are found to be at play. A model has been constructed, grounded in the contacts between PPG and the solvent during the coil-to-globule transition, to better understand the observed impact of AM on the clouding behavior of PPG aqueous solutions. The mechanism behind the enhanced solubilization has been ascribed to AM's ability to contact with PPG during the temperature-induced dehydration process, thereby assisting in sustaining the PPG's dissolved state.

Recent Developments on Ionic Liquids and Deep Eutectic Solvents for Drug Delivery Applications

The field of Ionic liquids (ILs) and deep eutectic solvents (DESs) is continuously expanding due to their exceptional unique properties and highly tunable nature, which finds applications in broad areas of modern science. Considering numerous possible IL and DES combinations prepared with active pharmaceutical ingredients (APIs), they find applications in pharmaceutical sciences. They can also serve as potential components of drug formulations and hence they have drawn the attention of formulation scientists. Herein, the concept of pharmaceutical ILs and DESs are discussed briefly. The possible applications of these solvent systems for slow drug delivery including nanoscale drug delivery are discussed citing various examples from the published literature. Although the ILs and DESs are found to be suitable for various drug delivery applications but still none of the slow drug delivery vehicles based on these solvents is in practical use. The data relating to long-term toxicity upon administration in the human body followed by various safety evaluations, clinical trials, etc. are pending for such new drug delivery systems. However, proof of concept studies done on the retention of biological activities in the ionic form is quite encouraging and such studies indicate the possibility of application of such new systems in the development of biomedical research and related industries in near future.