Most people may not know what an amphiphile is, but nearly everyone (at least we hope) interacts with soap on a regular basis. We bathe with it, wash our hands with it, shave with it, use it to clean dishes, and even blow bubbles with it. Clearly soap does a lot of helpful and interesting things, but how and why does it work? As it turns out, all the neat properties of soap are consequences of the fact that it is part of a larger class of molecules called amphiphiles.
Soap, like all amphiphilic molecules, consists of a polar half that attracts water and a non polar half that interacts with oils and fats. This is a miracle property considering that water ordinarily does not mix well at all with the oils, grease, dirt, and other gunk that accumulates on our bodies. So while rinsing alone might not not get the job done, covering ourselves with a frothy layer of soap is perfect for enveloping all the grime so that it can be easily carried away down the drain with plain old water.
The ability of soap molecules to spontaneously self-assemble around something leads to all kinds of other interesting properties. Soap bubbles, for example, are a consequence of soap molecules surrounding a very thin layer of water to enclose air. The thicker the layer of water inside, the more light waves bouncing off the inside and outside of the layer interfere, which causes the beautiful iridescent rainbow visible on the surface of a bubble. Soap also makes for a great lubricant for slip ‘n slides or shaving because the layer of water and soap creates more cushion between the two microscopically uneven surfaces at play.
Peptide Amphiphiles
Peptide amphiphiles are simply short proteins (peptides) that exhibit the same kinds of self-assembly behaviors we expect from other amphiphiles. In other words peptide amphiphiles are biologically-compatible Legos that can become all kinds of fascinating structures.
Self-assembly of peptide amphiphiles for drug delivery – Royal Society of Chemistry
The Freeman lab seeks to better understand the self-assembly behavior of peptide amphiphiles in order to build the next generation of biologically-compatible smart materials.