Amphipols are a new class of polymers that serve as stabilizers of membrane proteins in aqueous solutions. Amphipol A835 detergents can be used to keep membrane proteins soluble in detergent-free aqueous solutions while stabilizing them biochemically.
Structurally, the Amphipol molecule is amphipathic and consists of two faces on separate 3-dimensional planes. Strong hydrophilic functional groups reside on one side of the molecule and function to keep the complex soluble.
On the opposite side are long hydrophobic acryl chains which and serve to stabilize the membrane protein. The hydrophobic side of the molecule hugs the portion of the protein formally housed in the lipid environment.