Small-angle scattering in studies of long-chain omega-3 delivery systems

This account highlights small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) in studies of long-chain omega-3 polyunsaturated fatty acids (PUFAs) and their delivery systems. Fundamentals of small-angle scattering are introduced. Examples representing four colloidal PUFA delivery systems are described: 1. Particle systems where PUFAs are complexed with another molecule to form well-defined nanoscale objects in aqueous phase. 2. Periodic systems where PUFAs are located within self-organized amphiphilic molecules forming lyotropic liquid crystalline phases. 3. Continuous systems where PUFAs form network-like sponge phases and other phases extended toward micrometer scale and beyond. 4. Semiinfinite two-dimensional systems where macroscopic PUFA droplets are separated from water by a thin microscopic interface. Associated structural characteristics, applicability and limits of small-angle scattering, complementarities of X-rays and neutrons as well as possibilities to connect these ideas to the oxidative stability are discussed.