Amphiphilic molecules, which have one water-friendly (hydrophilic) end and one water-repellant (hydrophobic) end, spontaneously aggregate in aqueous solutions to make superstructures like capsules or bilayers.
This phenomenon is responsible for the effects of detergents and soaps. Dirt is enclosed in little capsules of surfactant, which makes it water-soluble. Cell membranes are also based on this principle: they are simply lipid bilayers, an aggregation of lipid molecules that line up with their hydrophobic tails all together and their hydrophilic heads protruding into the aqueous environment. As reported in the journal Angewandte Chemie , researchers at the Universities of Hamburg and Freiburg (Germany) led by Horst Weller and Stephan Förster have now produced amphiphilic hybrid particles made of a water-insoluble inorganic nanoparticle at the core surrounded by a bristle-like layer of hydrophilic polymer chains.