Onion Vesicle Illustration (image) University of Pennsylvania Caption University of Pennsylvania researchers have shown that a certain kind of dendrimer, a molecule that features tree-like branches, offers a simple way of creating vesicles and tailoring their diameter and thickness. Moreover, these dendrimer-based vesicles self-assemble with concentric layers of membranes, much like an onion. Each layer of membrane contains two sets of dendrimers sandwiched together, arranged so their water-loving branches (colored blue) face outward and their water-hating branches (green) face inward. This arrangement provides a stable, water-soluble package for the delivery of drugs, separate doses of which can be nestled between each layer. Credit University of Pennsylvania Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.