Polarity-Engineered Lipid Droplets for Selective Removal of Pharmaceutical Contaminants from Water
Pharmaceutical contaminants remain in aquatic environments because many traditional water treatment methods are energy-intensive, costly, or lack selectivity for chemically diverse drugs. A major challenge is the inability to modify extraction systems to selectively remove pharmaceuticals with different molecular properties, such as polarity, which influences solubility and environmental behavior. In this study, bioinspired synthetic plant lipid droplets (sLDs) were developed as a platform for the targeted isolation and removal of pharmaceutical contaminants from water. The polarity of the droplet core was systematically adjusted by blending nonpolar sunflower oil with castor oil, which is inherently more polar due to its high hydroxyl group content capable of hydrogen bonding. Increasing the castor oil fraction introduced greater hydrogen- bonding capacity and dipolar character into the lipid core. The distribution of five environmentally relevant pharmaceuticals between the water phase and the engineered lipid droplets was measured using liquid chromatography–mass spectrometry (LC–MS). Elevating the castor oil content increased the droplet core polarity and hydrogen- bonding capacity, thereby enhancing interactions with moderately polar pharmaceutical substances. These results demonstrate that lipid droplet composition can be engineered to control contaminant partitioning. This biodegradable, adaptable system offers a promising, energy-efficient method for removing pharmaceuticals from aquatic environments.